CN101578246B

CN101578246B - Process for manufacturing an LTM perovskite product

Info

Publication number: CN101578246B
Application number: CN2007800438531A
Authority: CN
Inventors: S·马兰; C·莱维
Original assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Current assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Priority date: 2006-10-24
Filing date: 2007-10-24
Publication date: 2013-03-20
Anticipated expiration: 2027-10-24
Also published as: FR2907471A1; CN101578246A; FR2907471B1

Abstract

The present invention relates to a fused product comprising an LTM perovskite, L denoting lanthane, T denoting an element chosen from strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and mixtures of these elements, and M denoting manganese.

Description

The method for preparing the LTM perovskite product

Technical field

The present invention relates to prepare the new method of lanthanum-strontium-manganese (LSM) perovskite.

Background technology

The term perovskite is used in reference to routinely for having ABO ₃Any material of type structure.

Lanthanum-strontium-manganese (LSM) perovskite is that wherein A is the lanthanum of doping strontium and the compound that B is manganese.Its structure is following type:

(La _(1-x)Sr _x) _(1-y)MnO ₃

Obtainable lanthanum-strontium-manganese perovskite powder is used in particular for the preparation of Solid Oxide Fuel Cell (SOFC) negative electrode in the market.Usually, they prepare by the following method:

Sol-gel/co-precipitation;

For example described by U.S. Patent No. 5 453 330, synthetic by the solid sintering; With

Synthetic and the pyrolysis by precursor.

Document " Nanomaterials:new elaboration processes using solarfurnaces ", Materials Science Forum, 269-272 rolls up (1998), and the 297-302 page or leaf has also been described the evaporation-condensation method.

Robert J.Bell, the article of Graeme J.Millar and John Drennan " Influence of synthetis route on the catalytic properties ofLa _1-xSr _xMnO ₃", Solid State Ionics 131 (2000), 211-220 have also described the method for 6 kinds of synthetic lanthanum-strontium-manganese perovskite powder.

The all powder that uses said method to obtain has the average particle size particle size of quite little (sub-micron) to medium (about 5 microns μ m).These powder are expensive.

Method for the preparation of monocrystalline lanthanum-strontium-manganese perovskite also is known, for example referring to EP 0,732 430.Yet these methods also are expensive.

Article " Effect of spray parameters on the electricalconductivity of plasma-sprayed La _1-xSr _xMnO ₃Coating for thecathode of SOFCs " coating that obtains by plasma spraying described.Described in the 279th page, such coating has the layer structure that casting product does not have.

Therefore have the needs to new method, the method can be prepared with the cost of reduction and with commercial quantities lanthanum-strontium-manganese perovskite.

The objective of the invention is to meet the need.

Summary of the invention

According to the present invention, realized this purpose by the method for preparing lanthanum-strontium-manganese perovskite, the method comprises following step:

A) raw material is mixed to form initial charge;

B) this initial charge is melted to obtain melt liquid; With

C) make this melt liquid solidify to form solid material;

Select described raw material, so that step c) in the solid material (" being called fused material ") that obtains have by weight percentage following chemical composition, altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

This material can be block or particle form.

In the first embodiment, the method thereby provide preparation to comprise the method for the particle of lanthanum-strontium-manganese perovskite, the method comprises following step:

a ₁) raw material is mixed to form initial charge;

b ₁) this initial charge is melted to obtain melt liquid;

c ₁) this melt liquid is disperseed with the drop form; With

d ₁) make described droplet solidification by contacting with oxygen-bearing fluid.

According to the present invention, at step a ₁) in, select described raw material, so that steps d ₁) in the solid particle (being called " consolidation particle ") that obtains have following chemical composition by weight percentage, altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

In the second embodiment, the invention provides the method that preparation comprises the block of lanthanum-strontium-manganese perovskite, the method comprises following consecutive steps:

a ₂) raw material is mixed to form initial charge;

b ₂) this initial charge is melted to obtain melt liquid;

c ₂) this melt liquid is cast in the mould;

d ₂) by cooling the liquid of casting is solidified in mould, until obtain at least part of block that solidifies; With

e ₂) with the described block demoulding.

According to the present invention, at step a ₂) in, select described raw material, so that the block of the demoulding has following chemical composition by weight percentage, altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

The present invention is conventional for the preparation of the method step of consolidation particle or consolidation block; and those skilled in the art will know that the how to confirm raw material so that obtain described chemical composition in described consolidation particle or described consolidation block, this forms and lanthanum-strontium-manganese perovskite (La _1-xSr _x) _1-yMnO ₃Composition identical, wherein 0＜x≤0.5 and-0.05≤y≤0.24.Yet the inventor finds that unexpectedly such conventional steps produces the Perovskite Phase of high percentage.

Conventional method is particularly implemented to jet or is atomized and only passes through to regulate the composition of initial charge with the method for making particle; therefore make it possible to be prepared by melt liquid particle or the block of different size; outside the removal of impurity; described particle or block have greater than 50%; be preferably greater than 70%; be preferably greater than 90%; more preferably greater than 99%, also more preferably greater than lanthanum-strontium of 99.9%-manganese perovskite percentage (this specification hereinafter provided the definition of lanthanum-strontium-manganese perovskite percentage in the product).Technology prejudice has been run counter in this beat all especially discovery, and this prejudice still causes those skilled in the art only to pay close attention to above-mentioned complexity and expensive method so far.

Preferably, the preparation method of the present invention's the first and second embodiments also comprises a kind of and preferred multiple following optional feature:

Determine initial charge, so that the particle of preparation or the chemical analysis results of block are as follows, by weight percentage, altogether 100%:

38.4%＜with La ₂O ₃The lanthanum of form meter＜69.7%;

0%＜in the strontium of SrO form＜25.4%;

30.3%＜in the manganese of MnO form＜37.2%; With

Impurity＜0.7%.

This forms and lanthanum-strontium-manganese perovskite (La _1-xSr _x) _1-yMnO ₃Composition identical, 0＜x≤0.5 and 0≤y≤0.1 wherein.

47.9%＜with La ₂O ₃The lanthanum of form meter＜69.7%;

0%＜in the strontium of SrO form＜17%;

30.3%＜in the manganese of MnO form＜35.7%; With

Impurity＜0.7%.

This forms and lanthanum-strontium-manganese perovskite (La _1-xSr _x) _1-yMnO ₃Composition identical, 0＜x≤0.35 and 0≤y≤0.1 wherein.

47.9%＜with La ₂O ₃The lanthanum of form meter＜61.6%;

6.7%＜in the strontium of SrO form＜17%;

31.5%＜in the manganese of MnO form＜35.7%; With

Impurity＜0.7%.

This forms and lanthanum-strontium-manganese perovskite (La _1-xSr _x) _1-yMnO ₃Composition identical, 0.15＜x≤0.35 and 0≤y≤0.1 wherein.

53.9%＜with La ₂O ₃The lanthanum of form meter＜61.6%;

6.7%＜in the strontium of SrO form＜11.8%;

31.5%＜in the manganese of MnO form＜34.7%; With

Impurity＜0.7%.

This forms and lanthanum-strontium-manganese perovskite (La _1-xSr _x) _1-yMnO ₃Composition identical, 0.15＜x≤0.25 and 0≤y≤0.1.

Preferably, " with La ₂O ₃The lanthanum of form meter " percentage by weight greater than 38.4%, be preferably greater than 47.9%, more preferably greater than 53.9%, and/or less than 69.7%, preferably less than 61.6%.

Preferably, the percentage by weight of " in the strontium of SrO form " is preferably greater than 6.7% greater than 0.8%, and/or less than 25.4%, preferably less than 17%, is more preferably less than 11.8%.

Preferably, the percentage by weight of " in the manganese of MnO form " is preferably greater than 31.5% greater than 30.3%, and/or less than 37.2%, preferably less than 35.7%, is more preferably less than 34.7%.

Preferably, the preparation method of first embodiment of the invention also comprises a kind of and preferred multiple following optional feature:

At step b ₁) in, use arc furnace;

At step c ₁) in, described melt liquid is contacted, preferably with steps d with oxygen-bearing fluid ₁In employed identical;

Dispersion and coagulation step are simultaneously;

Keep the contact between drop and the oxygen-bearing fluid, until described drop solidifies fully;

Step c ₁) and/or steps d ₁) in oxygen-bearing fluid (being preferably air) comprise at least 20 volume % or even the oxygen of at least 25 volume %; With

In steps d ₁) after, the consolidation particle is annealed.

Preferably, described particle at 1050 ℃-1400 ℃, is annealed under the preferred 1150 ℃ temperature, soaking is at least 30 minutes under this temperature, is preferably greater than 2 hours, is preferably about 5 hours.More preferably, described particle under the atmosphere that comprises at least 20 volume % oxygen, preferably under air, is preferable under the atmospheric pressure and anneals.

Preferably, the preparation method of second embodiment of the invention also comprises a kind of and preferred multiple following optional feature:

At step b ₂) in, use induction furnace;

At step c ₂) in and/or in steps d ₂) in and/or at step e ₂) after, making the melt liquid and the oxygen-bearing fluid that are solidifying, preferred oxygen-containing gas is air for example, directly or indirectly contact.Preferably, after with the block demoulding, at once begin described contact.More preferably, keep this contact until block solidifies fully;

The cooldown rate of solidificating period is opened/second (K/s) less than 1000 all the time, preferably less than 100K/s, is more preferably less than 50K/s;

Before solidifying fully, block carries out step e ₂) the demoulding;

Preferably, with the as quickly as possible demoulding of block, preferably when it has enough rigidity with its shape of basic maintenance, carry out the demoulding, and more preferably, this block is contacted with oxygen-bearing fluid;

At step e ₂) after, with the block annealing of the demoulding.Preferably with this block at 1050 ℃-1400 ℃, anneal under the preferred 1150 ℃ temperature, under this temperature, carry out soaking, soaking metering from the moment that whole block reaches soaking temperature (on the surface of this block and in the core of this block), all thermal endurance is preferably greater than 30 minutes, is preferably greater than 2 hours and is preferably about 5 hours.More preferably, described block under the atmosphere that comprises at least 20 volume % oxygen, preferably under air, is preferable under the atmospheric pressure and anneals;

Choose wantonly after annealing, for example by pulverizing and/or grinding, the in flakes broken or powder with the block of the demoulding.Then preferred application choice particle size on the estimation.

The present invention also provides the consolidation product of consolidation particle or consolidation block form; outside the removal of impurity; this product has greater than 50%; be preferably greater than 70%; more preferably greater than 90%; also more preferably greater than lanthanum-strontium of 99%-manganese perovskite percentage, this product has following chemical composition by weight percentage, and altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

Preferably, outside the removal of impurity, this product has the described formula (La greater than 99.9% _1-xSr _x) _1-yMnO ₃Lanthanum-strontium-manganese perovskite, wherein 0＜x≤0.5 and-0.05≤y≤0.24, the parameter x in the formula and y are the atomic ratio of each element.

Preferably, product of the present invention comprises a kind of and preferred more than a kind of following optional feature:

Use the method according to this invention to obtain maybe can obtain product of the present invention.

Product of the present invention has greater than 38.4%, is preferably greater than 47.9%, more preferably greater than 53.9%, and/or less than 69.7%, preferably less than 61.6% " with La ₂O ₃The lanthanum of form meter " percentage by weight.

Product of the present invention has greater than 0.8%, is preferably greater than 6.7%, and/or less than 25.4%, preferably less than 17%, is more preferably less than the percentage by weight of 11.8% " in the strontium of SrO form ".

Product of the present invention has greater than 30.3%, is preferably greater than 31.5%, and/or less than 37.2%, preferably less than 35.7%, is more preferably less than the percentage by weight of 34.7% " in the manganese of MnO form ".

Outside the removal of impurity, product of the present invention has the formula (La greater than 99.9% _1-xSr _x) _1-yMnO ₃Lanthanum-strontium-manganese perovskite, preferred x＞0.02, preferred 0.15＜x, and/or x＜0.35, preferred x＜0.25.

Outside the removal of impurity, product of the present invention has lanthanum-strontium greater than 99.9%-manganese perovskite and 0≤y and/or y≤0.1.

Advantageously, these rear two kinds of preferred characteristics (pr é f é rence) are given the high conductance performance of casting product and are made it be particularly suitable for the negative electrode of (may after grinding) preparation Solid Oxide Fuel Cell (SOFC).

Product of the present invention can have thickness greater than 1 millimeter (mm), is preferably greater than 2mm, is preferably greater than 5 centimetres (cm), and more preferably greater than the bulk shape of 15cm, the described thickness of block is its smallest dimension.This block preferably has the weight greater than 200 grams (g).

Product of the present invention also can show as grain shape, and it can have the optional feature below one or more:

Use the method according to this invention to obtain maybe can obtain particle of the present invention.

Particle of the present invention has greater than 38.4%, is preferably greater than 47.9%, more preferably greater than 53.9%, and/or less than 69.7%, preferably less than 61.6% " with La ₂O ₃The lanthanum of form meter " percentage by weight.

Particle of the present invention has greater than 0.8%, is preferably greater than 6.7%, and/or less than 25.4%, preferably less than 17%, is more preferably less than the percentage by weight of 11.8% " in the strontium of SrO form ".

Particle of the present invention has greater than 30.3%, is preferably greater than 31.5%, and/or less than 37.2%, preferably less than 35.7%, is more preferably less than the percentage by weight of 34.7% " in the manganese of MnO form ".

Outside the removal of impurity, particle of the present invention has the formula (La greater than 99.9% _1-xSr _x) _1-yMnO ₃Lanthanum-strontium-manganese perovskite percentage, preferred x＞0.02, preferred 0.15＜x, and/or x＜0.35, preferred x＜0.25.

Outside the removal of impurity, particle of the present invention has lanthanum-strontium greater than 99.9%-manganese perovskite and 0≤y and/or y≤0.1.Advantageously, these rear two kinds of preferred characteristics are given the high conductance performance of described particle and are made them be particularly suitable for the negative electrode of (may after grinding) preparation Solid Oxide Fuel Cell (SOFC).

Product of the present invention can also be that size is less than 4mm, for example less than the particle form of 3mm.The sphericity of particle can be preferably greater than 0.6 greater than 0.5, and wherein sphericity is defined as the ratio between its smallest dimension and its out to out.

Product of the present invention does not need the heat treatment of annealing after it solidifies or cools off, and/or does not need through grinding.

At last; the invention provides particle or block (may after the grinding) application in the preparation of Solid Oxide Fuel Cell (SOFC) negative electrode, described particle or block are by implementing method of the present invention or using particularly consolidation particle and producing of consolidation product of the present invention.

Outside the removal of impurity, the percentage of lanthanum-strontium-manganese perovskite uses following formula (1) definition:

T＝100×(A _LSM)/(A _LSM+A _{30.4＜2θ＜31.6}) (1)

Wherein:

A _LSMBe the bimodal area of master of the lanthanum-strontium without deconvolution processing that records at x-ray diffraction pattern-manganese perovskite, obtain described diffraction pattern by the D5000 diffractometer type device that is equipped with copper DX pipe from supplier Bruker; With

A _{30.4＜2 θ＜31.6}Be the area without deconvolution processing of those phases of recording at identical diffraction pattern, have diffraction maximum in the described angular range ° extend to 2 θ=31.6 from 2 θ=30.4.Especially, La ₂MnO ₄In this angular range, has diffraction maximum.

Generally speaking, term " consolidation product " refers to (may through annealing) solid product of obtaining by solidifying fully of fluid composition (being called " melt liquid " here).At step e ₂) " demoulding " product that obtains when finishing may still comprise the zone of ot-yet-hardened, and therefore at once it is not recognized as the consolidation product after the demoulding.

Term " consolidation particle " refers to by making fluid composition solidify the solid particle of (may through annealing) of gained.

Term particle " size " refers to the mean value of its out to out dM and its smallest dimension dm: (dM+dm)/2.

The thickness of block is its smallest dimension.

Term " impurity " refer to the inevitable inevitable composition of introducing with raw material or from the reaction of these compositions.

The below describes the method that the present invention in the first embodiment of the invention prepares particle in detail.

At step a ₁) in, use specific oxide or its precursor to form initial charge.Can regulate composition by the mixture that adds pure-oxide or oxide and/or precursor, particularly La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO or Mn ₃O ₄

In the present invention, those skilled in the art regulate the composition of initial charge, so that in steps d ₁) obtain particle of the present invention when finishing.The chemical analysis results of consolidation particle of the present invention usually and initial charge basic identical.Yet, when appropriate, those skilled in the art will know that composition how to regulate initial charge, for example for will be between melting stage the existence of volatile element or the disappearance of some element take into account.

Preferably, on one's own initiative will be except La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO and Mn ₃O ₄And the element outside the precursor is incorporated in the initial charge, and other element exists as impurity.

Preferably, La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO and Mn ₃O ₄And the total amount of precursor account for initial charge greater than 99 % by weight.

Can in blender, raw material closely be mixed.Then mixture is poured in the melting furnace.

At step b ₁) in, preferably in arc furnace, initial charge is melted.Electric smelting makes it possible to the standby a large amount of particles of favourable efficiency system.

For example, can use Heroult type arc furnace, this arc furnace have two electrodes and wherein container have about 0.8 meter (m) diameter and can hold about 180 kilograms of (kg) melt liquids.Voltage is preferably 140 volts of (V)-180V, and power is about 240 kilowatts (kW), and employed energy is 1150 kilowatt hours/(metric system) ton (kWh/t)-2800kWh/t.

Yet can expect any known smelting furnace, for example the Heroult stove of induction furnace, plasma furnace or other type needs only them and can make the complete melting of initial charge.And so nonessential, can improve the stirring quality by carrying out bubbling with oxidizing gas (for example air or oxygen), described in FR 1 208 577.Particularly can improve the quality that melt liquid is stirred by carrying out bubbling with the gas that comprises 35 volume % oxygen.

At step c ₁) in, the melt liquid material stream that is preferably 1600 ℃ of-1800 ℃ of temperature is dispersed into droplet.

Can be estranged loose by the miscarriage of winding-up melt liquid material.Yet can expect any other method of atomized molten liquid well known by persons skilled in the art.

In steps d ₁) in, by with oxygen-bearing fluid, preferably with gas, more preferably contact with air and/or steam and change drop into solid particle.Oxygen-bearing fluid preferably includes at least 20 volume %, or even the oxygen of at least 25 volume %.

In a single day preferably the method is modulated, so that form the drop of melt liquid, just at once it is contacted with oxygen-bearing fluid.More preferably, disperse (step c ₁) and solidify (steps d ₁) be basic simultaneously, described melt liquid disperses by the oxygen-bearing fluid that is suitable for cooling off and solidify this liquid.

Preferred before particle solidifies fully, the maintenance at least and the contacting of oxygen-bearing fluid.

Preferably, do not use except by contact other clotting method cooling off with oxygen-bearing fluid.Therefore, for example preferably do not use the drop with melt liquid to face toward the super quenching method that the cool metal wall sprays.

Cooldown rate is the function of particle diameter.Be about 1000K/s for this speed of the particle with 0.3mm size.

In steps d ₁) when finishing, obtaining solid particle of the present invention, described particle has the size of 0.01mm-3mm according to dispersion condition.

Advantageously, and in unexpected and unaccountable mode, melt liquid contacted with oxygen-bearing fluid make it possible under without any annealing steps lanthanum-strontium of obtaining commercial quantities with the cost that reduces and significant percentage-manganese perovskite, outside the removal of impurity, described percentage reaches greater than 90% and even greater than 99.9%.

Yet, can there be other phase, for example may be the impurity that produces from raw material.

In preferred embodiments, impurity is except the oxide of lanthanum, strontium and manganese and all the components except the combination of such oxide.

Especially, can find lower surface element as impurity: Al; Ca; Si; Zr; Na; Ba; And Fe.Preferably, in oxide form, content of impurities is less than 0.7 % by weight, preferably less than 0.4%, more preferably:

Al ₂O ₃＜0.5%, Al preferably ₂O ₃＜0.1%; And/or

CaO＜0.25%, preferably CaO＜0.05%; And/or

SiO ₂＜0.1%, SiO preferably ₂＜0.06%; And/or

ZrO ₂＜0.5%, ZrO preferably ₂＜0.05%; And/or

Na ₂O＜0.05%; And/or

BaO＜0.1%, preferably BaO＜0.06%; And/or

Fe ₂O ₃＜0.05％。

In steps d ₁) when finishing, obtain particle of the present invention.

At optional later step e ₁) in, particle is introduced in the stove with the heat treatment of annealing.Advantageously, such annealing is used for further improving the percentage of lanthanum-strontium-manganese perovskite.Outside the removal of impurity, this makes it possible to obtain substantially to equal lanthanum-strontium of 100%-manganese perovskite percentage.

Annealing temperature is preferably 1050 ℃-1400 ℃, more preferably 1100 ℃-1200 ℃, is more preferably about 1150 ℃.This temperature preferably kept being longer than 0.5 hour, preferably was longer than 2 hours and was preferably about 5 hours duration.Preferably, under the atmosphere that contains at least 20 volume % oxygen, preferably under air, be preferable under the ambient pressure of about 1 bar and implement described annealing heating temperature.

Before or after annealing, can grind consolidation particle of the present invention.In case of necessity, then use on the estimation and carry out the selection of particle size.

Particle of the present invention can advantageously have various sizes, and the preparation method is not limited to obtain the perovskite powder of sub-micron sized.Therefore it is very suitable for the industry preparation.

In addition, the gained particle can be advantageously used in the negative electrode of preparation Solid Oxide Fuel Cell (SOFC).

Embodiment

Provide for illustration purposes following embodiment, described embodiment does not limit the present invention.Prepare as follows particle tested.

At first, in blender, initiation material is closely mixed:

La by supplier Treibacher sale ₂O ₃Powder, this powder have greater than the purity of 99 % by weight with less than the median size of 45 μ m;

SrCO by supplier SPCH sale ₃Powder, this powder have greater than the purity of 96 % by weight and have the underflow that passes through 45 μ m sieve greater than 99%; With

MnO by supplier Delta sale ₂Powder, this powder have the median size greater than the purity of 91 % by weight and about 45 μ m.

The initial charge of 50 these weight of obtaining is by this way poured in the Heroult type electrometal furnace.Then implement fusing with its melting (energy that applies changes between 1300kWh/t-2800kWh/t according to embodiment for voltage: 160V, power: 240kW) with long arc, so that by complete and uniform mode melting entire mixture.Preparation condition is oxidizability.

In certain embodiments, described in FR 1 208 577, improve the stirring quality by carrying out bubbling with the gas that contains 35 volume % oxygen.

In case fully fusing casts melt liquid in order to form material stream.The temperature of the melt liquid that records during the casting is 1600 ℃-1800 ℃.

Then be dispersed into the drop of melt liquid with 3 bar pressures winding-up dried compressed air with broken material stream and with it.

The air of winding-up cools off drop and they is condensed with the form of consolidation particle.Depend on the air blast condition, the consolidation particle can be sphere or other form, can be hollow or solid.They have the size of 0.01mm-3mm usually.

Carry out chemical analysis and to having the percentage of sample determination lanthanum-strontium less than 40 μ m median size-manganese Perovskite Phase.

Carry out chemical analysis with x-ray fluorescence.

Use x-ray diffraction pattern to measure the percentage of lanthanum-strontium-manganese perovskite, described diffraction pattern is obtained by the D5000 diffractometer that is equipped with copper DX pipe from supplier Bruker.After fusing and solidifying, other La for example mutually that products obtained therefrom can comprise Perovskite Phase and small amount ₂MnO ₄

Use the ICDD card, adopt conventional criterion to determine lanthanum-strontium-manganese Perovskite Phase by X-ray diffraction.For example ICDD card No.00-053-0058 is applicable to La _0.8Sr _0.2MnO ₃Lanthanum-strontium-manganese Perovskite Phase.

In fact, when showing below, x-ray diffraction pattern carries out the measurement of lanthanum-strontium-manganese perovskite percentage:

Main lanthanum-strontium-manganese Perovskite Phase;

2 θ angles are 30.4 ° of-31.6 ° of less important phases of locating; With

In order to measure other the less important phase that does not have the peak in the angular range that above-mentioned phase considers.

Then, use EVA software (being sold by supplier Bruker) and after deduction continuous background (background 0.8), can be to the phase of all existence (particularly including La ₂MnO ₄) measure the area (without deconvolution processing) between 2 θ=30.4 ° and 31.6 °, and the bimodal area (without deconvolution processing) of the master of lanthanum-strontium-manganese perovskite.Then use formula (1) to calculate the percentage of lanthanum-strontium-manganese perovskite.

Therefore, if lanthanum-strontium-manganese perovskite is the unique phase that exists in the x-ray diffraction pattern, so A _{30.4＜2 θ＜31.6}Be zero, then perovskite percentage equals 100%.

Table 1 has gathered the result who obtained before any annealing heat treatment.

Table 1

Table 1 has shown the validity of the inventive method.

Then below under the condition to embodiment 1 ₁Product heat-treat:

Temperature: 1150 ℃;

Soaking time: 5 hours;

Atmosphere: be in the air under the atmospheric pressure (ambient pressure).

After heat treatment, outside the removal of impurity, this product has lanthanum-strontium of 100%-manganese perovskite percentage.

The below describes the method that the present invention who uses second embodiment of the invention prepares the consolidation block in detail.

At step a ₂) in, by above-mentioned steps a ₁) determine initial charge, for preferred characteristics, particularly relate to the selection that has element or relate to those characteristics that their are measured, with above-mentioned steps a ₁) in identical.

In the present invention, those skilled in the art regulate the composition of initial charge so that at step e ₂) obtain according to block of the present invention when finishing.The chemical analysis results of block of the present invention is identical with initial charge basically usually.Yet, when appropriate, those skilled in the art will know that composition how to modulate initial charge, for example in order to the existence of volatile element between melting stage or the disappearance of some element are taken into account.

At step b ₂) in, for example in arc furnace, with the initial charge fusing, in order in complete and uniform mode whole initial charge are melted.

Electric smelting makes it possible to the standby large block of favourable efficiency system, and described block may have the thickness of 150mm.For example, can use Heroult type arc furnace, this arc furnace has two electrodes and has the container that about 0.8m diameter also can hold about 180kg melt liquid.The voltage that uses is preferably 140V-180V, and power is about 240kW, and energy is 1150kWh/t-2800kWh/t.

Yet can expect any known stove, for example the Heroult stove of induction furnace, plasma furnace or other type needs only them and can make the complete melting of initial charge.And so nonessential, can improve the stirring quality by carrying out bubbling with oxidizing gas (for example air or oxygen), described in FR 1 208 577.Can be especially by carrying out the stirring quality that bubbling improves melt liquid by the gas that contains 35 volume % oxygen.

For example press described in the FR 1 430 962, induction furnace is most preferred.Therefore advantageously, can be before block solidifies fully and the core of block is carried out the demoulding when being still liquid.As in being described below as seen, this early stage demoulding advantageously improves the percentage of lanthanum-strontium-manganese perovskite.

The temperature of the melt liquid that records during the casting is preferably 1600 ℃-1800 ℃.

At step c ₂) in, melt liquid is cast to is suitable for standing in the mould of melt liquid body lotion.The preferred use by graphite or the mould that is made of cast iron or such as the mould defined in the U.S. Patent No. 3 993119.When adopting induction furnace, think that wire turn consists of mould.Preferably in air, cast.

In steps d ₂) in, will be poured into liquid cools in the mould to obtain at least part of block that solidifies.

At solidificating period, preferably make melt liquid and oxygen-bearing fluid, preferred gas, preferred contact with air.In case casting begins namely to carry out this contact.Yet, preferred until just begin this contact after the casting.For actual cause, only after the demoulding, beginning as quickly as possible after the demoulding and preferably with contacting preferably of oxygen-bearing fluid.

Oxygen-bearing fluid preferably comprises at least 20 volume % or even the oxygen of at least 25 volume %.

Preferably, before solidifying fully, block keeps and the contacting of oxygen-bearing fluid.This contact can be directly, for example for the surface that is cast to the melt liquid in the mould, and the interface of formation and surrounding air.It can also be indirectly, and for example for the liquid of melting still in the block core, the outer surface of described block solidifies.Then must make " wall " that oxygen passes through to consist of in such a way in order to arrive melt liquid.

Preferably, after solidifying beginning, less than 1 hour, preferably less than 30 minutes, be more preferably less than 20 minutes described melt liquids that solidifying that make of beginning and contact with oxygen-bearing fluid.

Advantageously, in unexpected and unaccountable mode, melt liquid is contacted the percentage that improves lanthanum-strontium in the consolidation block of the present invention-manganese perovskite in remarkable mode with oxygen-bearing fluid, until basic 100%.In order to obtain such percentage, need not afterwards annealing steps.

In addition, the inventor finds that the cooldown rate of solidificating period is not to improve the deciding factor of lanthanum-strontium-manganese perovskite percentage.Therefore remain that preferably cooldown rate is lower than 1000K/s, preferably be lower than 100K/s, more preferably less than 50K/s.Advantageously, can therefore use conventional simple cooling means.Preferably, solidify for making melt liquid, that is, it is condensed, only use the mould that contacts or loop by heat transfer fluid especially cooling with surrounding air, perhaps when block being taken out from mould and contain melt liquid, block is contacted with oxygen-bearing fluid.Thereby improve reliability and expense.

At step e ₂) in, with the block demoulding.For being conducive to that melt liquid is contacted with oxygen-bearing fluid, if before solidifying fully can, then preferably as quickly as possible with the block demoulding.Then at step e ₂) in continue to solidify.

Preferably, in case when block has the rigidity that can substantially keep its shape it is carried out the demoulding.Preferably, with the as quickly as possible demoulding and it is contacted with oxygen-bearing fluid of block.

Preferably, after solidifying beginning, carry out the demoulding in less than 20 minutes.

After solidifying fully, obtain block of the present invention, this block comprises the amount of the lanthanum-strontium of raising-manganese perovskite, and the raising degree is identical with following situation: melt liquid is contacted with oxygen and then keep being in contact with it at the solidificating period commitment.

At optional step f ₂) in, the block of the demoulding is put into stove with the heat treatment of annealing.Advantageously, such annealing makes it possible to significantly improve the percentage of lanthanum-strontium-manganese perovskite.Therefore can obtain greater than 99%, be preferably greater than 99.9% and even substantially equal lanthanum-strontium of 100%-manganese perovskite percentage (outside the removal of impurity).

When lanthanum-strontium-manganese perovskite percentage (outside removal of impurity) greater than 99.9% the time, the Nomenclature Composition and Structure of Complexes of lanthanum-strontium-manganese perovskite can be used formula (La _1-xSr _x) _1-yMnO ₃The expression, wherein 0＜x≤0.5 and-0.05≤y≤0.24, the parameter x in the formula and y are the atomic ratios of each element.

Advantageously, annealing heat treatment improves the percentage of lanthanum-strontium-manganese perovskite, even any melt liquid is contacted with oxygen-bearing fluid, for example because the block of preparation fully solidifies when the demoulding, and in mould, cool off or it is contacted with oxygen-bearing fluid at it.

The annealing heat treatment parameter is the dependent variable of the yardstick of processed block.Preferably, these parameters are as follows:

Annealing temperature: be 1050 ℃-1400 ℃, preferred about 1150 ℃; With

Equal thermal endurance at a certain temperature: greater than 30 minutes, be preferably greater than 2 hours, preferred about 5 hours, from the moment that whole block reaches soaking temperature (on the surface of this block and in the core of this block).For example, all less than the block of 5mm, all thermal endurance is preferably about 5 hours for all yardsticks.For the cylindrical block with 200mm diameter and 150mm height, all thermal endurance is preferably about 12 hours.

In all cases, preferably under the atmosphere that comprises at least 20 volume % oxygen, preferably under air, be preferable over the heat treatment of annealing under the ambient pressure of about 1 bar.

Annealing heat treatment must be carried out after block solidifies fully.Yet before annealing, can be with the broken in blocks or powder of block.Preferably block is ground to form and have about 5mm or less than the particle form of 5mm size.

Method of the present invention produces has the block of the present invention that is mainly lanthanum-strontium-manganese Perovskite Phase.Especially, after annealing heat treatment, outside the removal of impurity, annealing block of the present invention or particle have greater than 99%, are preferably greater than 99.9%, are preferably lanthanum-strontium of 100%-manganese perovskite percentage.

Yet, can there be other phase, for example may be the impurity from raw material.Impurity is except the oxide of lanthanum, strontium and manganese and all elements except the combination of described oxide.

Especially, can find lower surface element as impurity: Al; Ca; Si; Zr; Na; Ba; And Fe.Preferably, in the impurity total weight percent of oxide form less than 0.7%, preferably less than 0.4%.More preferably:

Al ₂O ₃＜0.5%, Al preferably ₂O ₃＜0.1%; And/or

CaO＜0.25%, preferably CaO＜0.05%; And/or

SiO ₂＜0.1%, SiO preferably ₂＜0.06%; And/or

ZrO ₂＜0.5%, ZrO preferably ₂＜0.05%; And/or

Na ₂O＜0.05%; And/or

BaO＜0.1%, preferably BaO＜0.06%; And/or

Fe ₂O ₃＜0.05％。

Block of the present invention can advantageously have any yardstick, and the preparation method is not limited to obtain the perovskite powder of sub-micron sized.

Therefore this block is very suitable for the industry preparation.Preferably, this block has greater than 1mm, is preferably greater than 2mm, is preferably greater than 5cm, and more preferably greater than the thickness of 15cm, wherein the thickness of block is its smallest dimension.

In order for example to obtain the powder for the preparation of the negative electrode of Solid Oxide Fuel Cell (SOFC), the block that will choose subsequently annealing wantonly pulverizes and is ground to required particle size.Advantageously, method of the present invention makes it possible to prepare the particle with various yardsticks, and cost is low.

Preferably, the block of the demoulding is at first pulverized into the sheet of 0-5mm.Then to the described heat treatment of annealing, subsequently it is ground to required particle size.

Provide for illustration purposes following embodiment, described embodiment does not limit the present invention.Block is tested in preparation as follows.

At first, will with closely mix in blender for the identical initiation material of those initiation materials of the embodiment of first embodiment of the invention.

The initial charge that obtains by this way is poured in the electrometal furnace.Use long arc to carry out melting so that with complete and uniform mode melting entire mixture.Preparation condition is oxidizability.The temperature of the melt liquid that records during the casting is 1600 ℃-1800 ℃.

Then in air, melt liquid is cast in the various moulds: the mould that the mould that is made of cast iron, graphite are made or such as the mould defined in the U.S. Patent No. 3 993 119.

By the cooldown rate in the following formula definition list 2 " Vr ":

Vr＝(Tf-Ts)/t _r

The temperature of melt liquid during wherein Tf refers to cast (in ℃), Ts refers to that block solidifies temperature constantly (in ℃) fully at it, and t _rBeginning and the block time (in second) between solidifying constantly fully refers to cast.

To grind into powder and the sample that is representing the block of casting carry out the mensuration of chemical analysis and lanthanum-strontium-manganese Perovskite Phase.Described powder has the median diameter less than 40 μ m.

Carry out chemical analysis with x-ray fluorescence.

By above measuring lanthanum-strontium-manganese perovskite percentage about the described x-ray diffraction pattern of the embodiment that relates to the first embodiment.

Table 2 and 2 ' has gathered the result who obtained before any annealing heat treatment.

Bubbling does not pass into gas between melting stage.

Embodiment 8 and 9 relates to makes prepared with the following method block: the method utilization is according to the induction melting of FR 1 430 962, and the diameter of wire turn is 275mm, and power is 120kw-220kw, and the frequency that the aperiodicity generator provides is 100kHz-250kHz.

" D999, h888 " refers to have the cylinder of the height h of the diameter D of 999mm and 888mm.

Table 2

Embodiment	Voltage (V)	The energy that applies (kWh/t)	The quality (kg) of the charging of fusing	Mould-type	Vr (℃/s)	The yardstick (mm) of casting block
							1 ₂	140	1200	50	According to US3993119	30	Thickness: the recessed 134mm of 5mm radius
2 ₂	150	2400	46	Graphite	0.055	180×180×150
							3 ₂	150	1400	46	Graphite	0.055	180×180×150
4 ₂	150	1400	46	Cast iron	0.055	D200，h150
							5 ₂	150	1400	46	Cast iron	0.055	D200，h150
6 ₂	180	1400	50	Cast iron	0.055	D200，h150
							7 ₂	180	1400	50	Cast iron	0.055	D200，h150
8 ₂	-	-	75	The wire turn of coil	0.04	D275，h190
							9 ₂	-	-	75	The wire turn of coil	0.04	D275，h190

Table 2 '

Table 2 ' shown the validity of the inventive method.Also make it possible to observe, (embodiment 8 between melting stage being undertaken by induction ₂With 9 ₂), wherein the surface of demoulding block contacts with airborne oxygen quickly (in these embodiments at the most after 20 minutes, at this moment block solidifies not yet fully), the percentage of lanthanum-strontium in the final products-manganese perovskite is very high, reach basic 100%, therefore advantageously make the heat treatment of annealing become meaningless.

Subsequently to embodiment 1 ₂, 2 ₂, 4 ₂With 5 ₂The heat treatment (table 2) of annealing.To the heat treatment (embodiment 1) of annealing of casting block or the block that is crushed to the 0-5mm scope.Stipulated employed heat treatment parameter in the table 3.In air, heat-treat.

Table 3

Table 3 has shown that this processing causes the obvious raising of lanthanum-strontium-manganese perovskite percentage, up to basic 100%.

Can be clear that in this point, method of the present invention makes it possible to prepare in simple and cheap mode the product of commercial quantities, particularly particle and block, described product has high lanthanum-strontium-manganese perovskite percentage and has following chemical analysis results, by weight percentage, altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

The method even make it possible to preparation and have greater than 99.9% or even the formula (La of 100% (outside the removal of impurity) _1-xSr _x) _1-yMnO ₃The product of lanthanum-strontium-manganese perovskite, 0＜x≤0.5 and-0.05≤y≤0.24.

If product purpose needs, then then can reduce the yardstick of product, for example with they grind into powder forms.

Certainly, the invention is not restricted to illustrative and non-limiting example and the embodiment of describing and providing.

Except elements strontium, the present invention relates to comprise the product of the product of LTM perovskite, particularly particle or block form, wherein L refers to lanthanum, T is the element that is selected from the mixture of strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and these elements, and M refers to manganese.The present invention also provides the method for preparing this product.

Think that the embodiment (wherein element T is not limited to strontium) that relates to these products and method is " broad sense ".

Common way is with ABO ₃Form represents the structure of such LTM perovskite.Yet, being entirely accurate, such perovskite has (La _(1-x)T _x) _(1-y)MnO _(3-δ)The structure of type.If have greater than 99.9% LTM perovskite percentage and the element total amount that consists of perovskite based on oxide weight percentage meter greater than 99% such as fruit product, then can and/or determine the value of x and y by chemical analysis by x-ray diffraction pattern.Because perovskite is electroneutral, so the δ value is corresponding to guaranteeing that perovskite structure is the required value of electric neutrality.What It is generally accepted is that the δ value depends on the valence state of element manganese substantially.

As described in calling the turn according to the order of sequence, above-mentioned LTM perovskite powder is used in particular for using complexity and expensive methods to prepare the negative electrode of Solid Oxide Fuel Cell.Therefore have the needs to the product that comprises the LTM perovskite, described product can be prepared by the cost and the commercial quantities that reduce.The objective of the invention is to meet the need.

More accurately, in present Solid Oxide Fuel Cell (SOFC), usually be divided into each electrode two-layer.In the special case of negative electrode, ground floor serves as current collector layers (CCL).One of raw material that is used as cathode material in the SOFC technology is the powder of lanthanum-manganese (LTM) perovskite of doping.

Be called " cathode functional " active layer (CFL) in the negative electrode between CCL and electrolyte, and must make it possible to supply with electronics in order to will be O from the hydrogen reduction of air to system simultaneously ^2-Ion and with these O ^2-Ion is sent in the electrolyte.For like this, the mixture by ion conductive material and electronic conductive material (lanthanum of doping-manganese perovskite) consists of this activity CFL usually.Must make the optimization that contacts between this bi-material and the air, namely the number of triple point (pointtriple) must be many as far as possible, and must have the particle diafiltration to various materials.

The zirconia that mixes (with the cubic zirconia of stabilized with yttrium oxide, with the stable cubic zirconia of scandium ...) be typically used as electrolyte or be used for functional cathode layer.

Therefore the contact between the Zirconium oxide powder that mixes and the lanthanum of the doping-manganese perovskite powder is closely, and the contact point number between these two kinds of powder is many.

The doping lanthanum of cathode material-manganese perovskite can react with electrolytical doped zirconia, with the at the interface formation cenotype at them, particularly La ₂Zr ₂O ₇The pyrochlore-type phase, especially in the formula of LTM perovskite x less than 0.4, or even less than 0.3 o'clock.The existence of these phases reduces the performance of battery.

Thereby for improving the performance of SOFC, existence only forms a small amount of La to being suitable for when contacting with the doped zirconia powder ₂Zr ₂O ₇The needs of the doping lanthanum of pyrochlore-type phase-manganese perovskite.

Another object of the present invention is to meet the need.

According to the present invention; by the consolidation product made by the LTM perovskite particularly particle or block form Realization of Product these purposes; wherein L refers to lanthanum, and T is the element that is selected from the mixture of strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and these elements, and M refers to manganese.

Product of the present invention can be pressed especially powder type and exist.The size of particle can be especially greater than 1 μ m, or greater than 10 μ m, or greater than 0.25mm, and/or less than 3mm.

This powder can comprise especially greater than 90 % by weight, or greater than the consolidation particle of the LTM perovskite of the present invention of 95 % by weight or basic 100 % by weight.

Product of the present invention is consolidation, and namely then it also solidify acquisition by fusing.Although the preparation of fusing-congealed prod is known, the inventor's contribution is to find to make it possible to prepare the technology of the product that contains the LTM perovskite.Advantageously, product of the present invention can thereby be prepared with low expense and commercial quantities.

Product of the present invention can be annealing product, or unannealed product, the product of namely not heat-treating after it solidifies.

In addition, such as following more detailed explanation, product of the present invention always produces still less pyrochlore-type La than the prior art products with identical chemical composition with the contact of the Zirconium oxide powder of doped yttrium oxide the time ₂Zr ₂O ₇Phase.Therefore it is particularly well adapted for preparing the negative electrode of SOFC.

The content of gained LTM perovskite and character depend on the composition of initial charge especially.Yet product of the present invention is polycrystalline all the time.

In embodiments of the invention, outside the removal of impurity, the consolidation product has the LTM perovskite percentage greater than 50%, and described perovskite has lanthanum, element T and manganese and divides other molar ratio l _p, t _pAnd m _p, use following representation:

x = \frac{t_{p}}{(l_{p} + t_{p})}

With

y = 1 - \frac{(l_{p} + t_{p})}{m_{p}}

X＞0, preferred x＞0.02, preferred x＞0.15, and/or x≤0.5, preferred x≤0.4, preferred x＜0.35, preferred x≤0.3, preferred x＜0.25; With

Y 〉=-0.1, preferred y 〉=-0.05, preferred y 〉=0, and/or y≤0.24, preferred y≤0.1.

Variable x and y are corresponding to (the La of the LTM perovskite of product of the present invention _(1-x)T _x) _(1-y)MnO _(3-δ)Structure Atom ratio x and y.

This specification has provided the definition of the LTM perovskite percentage of product hereinafter.

Preferably, product of the present invention comprises one and preferred a plurality of following optional feature:

Outside the removal of impurity, LTM perovskite percentage is preferably greater than 90% greater than 70%, is preferably greater than 99%, more preferably greater than 99.9%, or even be 100%;

Obtain maybe can obtain product of the present invention by the inventive method of hereinafter more describing in detail;

Employed element T is selected from calcium, strontium, barium, magnesium and composition thereof.Element T is calcium and/or strontium preferably.

Impurity content is less than 1%, preferably less than 0.7%.

Advantageously, these character are improved the conductivity performance, make product be particularly suitable for the negative electrode of (choosing wantonly after grinding) preparation Solid Oxide Fuel Cell (SOFC).

Product of the present invention does not need to carry out annealing in process after cooling, and/or does not need through grinding.

The present invention also provides preparation to comprise the method for the consolidation product of LTM perovskite, wherein L refers to lanthanum (La), T is the element that is selected from the mixture of strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and these elements, and M refers to manganese (Mn), and the method comprises following step:

A ') will provide the raw material of lanthanum, element T and manganese to mix, in order to form initial charge;

B ') this initial charge is melted to obtain melt liquid;

C ') cools off described melt liquid until it solidifies fully, in order to obtain the consolidation product.

Thereby, conventional fusing-clotting method is only by regulating the composition of initial charge, make it possible to be prepared by melt liquid the consolidation product of different size, outside the removal of impurity, described product has greater than 50%, is preferably greater than 70%, be preferably greater than 90%, more preferably greater than 99%, also more preferably greater than 99.9%, or even basic 100% LTM perovskite percentage.

Technology prejudice has been run counter in this beat all especially discovery, and this prejudice causes those skilled in the art only to pay close attention to above-mentioned complexity and expensive method in the past.

Preferably, preparation method of the present invention also comprises a kind of and preferred multiple following optional overall characteristic:

Determine the amount of lanthanum, element T and manganese in selected element T and the initial charge, so that at step c ') product that obtains when finishing meets the present invention;

Element T is the lanthanum dopant that is selected from calcium, strontium, barium, magnesium and composition thereof.These dopants significantly improve the conductivity of LTM perovskite;

At least a among element L, T and the M introduced with oxide form;

Provide the compound of element L, T and M account for altogether the initial charge composition greater than 90% and be preferably greater than 99% percentage by weight.These compounds preferably account for 100% of initial charge composition with impurity;

Provide the compound of L, T and M to be selected from SrO, SrCO ₃, La ₂O ₃, CaO, CaCO ₃, Y ₂O ₃, Yb ₂O ₃, MgO, MgCO ₃, CeO ₂, BaO, MnO ₂, MnO or Mn ₃O ₄

At step b ') in, plasma torch or fan heater do not used.Especially, use arc furnace or induction furnace.

In the first broad sense embodiment, the present invention relates to the product and the method for preparing such particle of particle form.

Especially, the invention provides comprise step a '), b ') and c ') the preparation method, and step c ') comprise following step:

c ₁') melt liquid is dispersed into the drop form; With

d ₁') make described droplet solidification by contacting with oxygen-bearing fluid, in order to obtain the consolidation particle.

Preferably the method is modulated in order to obtain the particle of LTM perovskite product of the present invention.

Conventional process for dispersing is only by regulating the composition of initial charge, particularly by winding-up or atomizing, therefore make it possible to begin to prepare from melt liquid the particle of different size, outside the removal of impurity, described particle has greater than 50%, is preferably greater than 70%, more preferably greater than 90%, more preferably greater than 99%, also more preferably greater than 99.9%, even basic 100% LTM perovskite percentage.

In the first broad sense embodiment, preparation method of the present invention preferably also comprises one and preferred more than a general option characteristic listed above and/or following particular characteristics:

At step b ₁') in, do not use plasma torch or fan heater.For example, use arc furnace.Advantageously, this has improved productive rate.In addition, the method for using plasma torch or fan heater is usually so that can not prepare and have greater than 200 μ m or at least greater than the particle of 500 μ m sizes;

At step c ₁') and/or steps d ₁') in, described melt liquid is contacted with oxygen-bearing fluid, described oxygen-bearing fluid preferably with steps d ₁') in employed oxygen-bearing fluid identical;

Described oxygen-bearing fluid, preferred gas, preferred air, comprise at least volume 20% or even the oxygen of volume 25% at least;

Dispersion and coagulation step are simultaneously;

Keep the contact between drop and the oxygen-bearing fluid, until described drop solidifies fully; With

The consolidation particle can be annealed.Preferably with described particle at 1050 ℃-1400 ℃, anneal under preferred about 1150 ℃ temperature, at high temperature soaking time is at least 30 minutes, is preferably greater than 2 hours, is preferably about 5 hours.More preferably, they under the atmosphere that comprises at least 20 volume % oxygen, preferably under air, are preferable under the atmospheric pressure and anneal.

Application grinding consolidation particle and/or it is carried out selection operation of particle size on the estimation, for example by screening, the special so that particle that obtains has greater than 1 μ m, or greater than 10 μ m and/or less than the size of 3mm.

In the second broad sense embodiment, the present invention relates to the product and the method for preparing such block of block form.

c ₂') melt liquid is cast in the mould;

d ₂') by cooling the liquid that is cast in the mould is solidified, to obtain at least part of block that solidifies; With

e ₂') with the described block demoulding.

In the second broad sense embodiment, preparation method of the present invention preferably also comprises one and preferred more than a general option characteristic listed above and/or following particular characteristics:

At step b ₂') in, use induction furnace;

At step c ₂') in and/or steps d ₂') in and/or at step e ₂') after, the described melt liquid that is solidifying is directly or indirectly contacted with oxygen-bearing fluid, described oxygen-bearing fluid preferably comprise at least 20% or even at least 25% oxygen, preferably gas is more preferably air;

After with the block demoulding, at once begin described contact;

Keep described contact until block solidifies fully;

Implementation step e before block solidifies fully ₂') the demoulding;

Block when having the rigidity that can substantially keep its shape, it is carried out the demoulding;

The cooldown rate of solidificating period melt liquid preferably less than 100K/s, is more preferably less than 50K/s all the time less than 1000K/s.When using cast iron die or graphite jig, cooldown rate is preferably less than 1K/s;

At step e ₂') after, the block of the demoulding is annealed.Preferably, with this block at 1050 ℃-1400 ℃, anneal under the preferred 1150 ℃ temperature, at high temperature carry out the soaking of certain duration, this duration is meter from the moment that whole block reaches soaking temperature (on the surface of this block and in the core of this block), be preferably greater than 30 minutes, be preferably greater than 2 hours, preferred about 5 hours.More preferably, this block under the atmosphere that contains at least 20 volume % oxygen, preferably under air, is preferable under the atmospheric pressure and anneals; With

The in flakes broken or powder with the demoulding block of optional annealing.

No matter consider which type of embodiment, all can have the phase except the LTM perovskite, and the impurity that is produced by raw material.

In preferred embodiments, impurity is all elements except the combination of lanthanum, element T and manganese and these elements.

Especially, can find lower surface element as impurity: Al; Si; Zr; Na; And Fe, or even the Ba when element T does not comprise respectively barium, strontium, magnesium, yttrium, ytterbium, cerium or calcium; Sr; Mg; Y; Yb; Ce or Ca.Preferably, in oxide form, the impurity total weight percent preferably less than 0.7% weight, is more preferably less than 0.4% less than 1%.More preferably:

Al ₂O ₃＜0.5%, Al preferably ₂O ₃＜0.15%, more preferably Al ₂O ₃＜0.1%; And/or

SiO ₂＜0.1%, SiO preferably ₂＜0.07%, preferred SiO ₂＜0.06; And/or

ZrO ₂＜0.5%, preferred ZrO ₂＜0.1%, ZrO preferably ₂＜0.05%; And/or

Na ₂O＜0.1%, preferred Na ₂O＜0.07, preferred Na ₂O＜0.05%; And/or

Fe ₂O ₃＜0.05％。

At last, the present invention relates to by the inventive method preparation or the consolidation product that is suitable for preparing or the application of consolidation product of the present invention in the negative electrode preparation of Solid Oxide Fuel Cell (SOFC).

Outside the removal of impurity, LTM perovskite percentage uses following formula (1) definition:

T=100 * (A _LTM)/(A _LTM+ A _{Inferior looks}) (1)

Wherein:

A _LTMBe x-ray diffraction pattern record without the diffracted primary peak of the LTM Perovskite Phase of deconvolution processing or the area of main multiplet, this diffraction pattern is obtained by the D5000 diffractometer type device that is equipped with copper DX pipe from supplier Bruker; With

A _{Inferior looks}The diffracted primary peak of the inferior looks that records during on identical diffraction pattern and without deconvolution processing or the area of main multiplet.Inferior looks is the less important phase that has main peak or the multiplet of maximum area when ignoring the LTM perovskite.Especially, La ₂MnO ₄Can be the inferior looks of determining at x-ray diffraction pattern mutually.

Multiplet is partly overlapping a plurality of peak.For example, the multiplet that is made of two peaks is bimodal, and the multiplet that is made of three peaks is triplet.

The below describes the method for the first broad sense embodiment according to the present invention in detail.

At step a ₁') in, by (particularly oxide or the carbonate form) compound of lanthanum, element T and manganese or by the precursor of elements La, T and manganese, form the initial charge that is suitable for preparing particle of the present invention.Can be by adding pure oxide or mixture, particularly SrO, the SrCO of oxide and/or precursor ₃, La ₂O ₃, CaO, CaCO ₃, Y ₂O ₃, Yb ₂O ₃, MgO, MgCO ₃, CeO ₂, BaO, MnO ₂, MnO or Mn ₃O ₄Regulate composition.The use of oxide and/or carbonate improves the availability that forms the perovskite requisite oxygen, and is preferred therefore.

In fact identical in the consolidation product of the amount of lanthanum, element T and manganese and preparation in the initial charge.During the fusing step, some these compositions are volatilizable, and the amount of described composition can change with melting condition.Based on general knowledge, perhaps by carrying out simple routine test, how to those skilled in the art will know that the amount of regulating these compositions in the initial charge according to amount required in the consolidation product or the melting condition implemented.

The particle size of the powder that uses can be those that usually run in the consolidation method.

Except the compound that elements La, T and manganese are provided, basic mixture also can comprise other compound, introduces these other compounds and carries out the contrast of particular characteristic in order to the particle to preparation.

Yet the preferred compound of not introducing in the initial charge on one's own initiative except the compound that elements La, T and manganese are provided is not particularly initiatively introduced except La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO, Mn ₃O ₄, CaO, CaCO ₃, Y ₂O ₃, Yb ₂O ₃, MgO, MgCO ₃, CeO ₂, the compound outside the BaO, other element exists as impurity.In embodiments, La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO, Mn ₃O ₄, CaO, Y ₂O ₃, Yb ₂O ₃, MgO, CeO ₂, BaO and their precursor total amount account for initial charge greater than 99 % by weight.

Preferably, provide the compound of elements La, T and manganese to be selected from La ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO, Mn ₃O ₄, CaO, CaCO ₃With their precursor, the total amount of these compositions preferably account for initial charge greater than 99 % by weight.Also preferably, in initial charge, do not introduce except La on one's own initiative ₂O ₃, SrO, SrCO ₃, MnO ₂, MnO, Mn ₃O ₄, CaO, CaCO ₃Outside compound, other element is that impurity exists.

For improving LTM perovskite percentage, the molar ratio of element L, T and M preferably approaches the described molar ratio of the perovskite that needs preparation in the initial charge.

Therefore, in initial charge, element L, T and Mg divide other molar ratio l _d, t _dAnd m _d, with respect to ratio l _d, t _dAnd m _dThe molar percentage meter of total amount, preferred satisfy below condition:

k ₁. (1-x). (1-y)≤l _d/ m _d≤ k ₂. (1-x). (1-y) (1) and/or

k ₁.x.(1-y)≤t _d/m _d≤k ₂.x.(1-y) (2)

Wherein

The value of x and the desirable above-mentioned restriction of y, especially: 0＜x≤0.5 and-0.1≤y≤0.24

K ₁Equal 0.8, preferably equal 0.9; With

K ₂Equal 1.2, preferably equal 1.1.

Naturally, these k ₁And k ₂Value is those values of using under the operating condition of establishing, namely ignores the transitional face between different the composition and ignores initial period.If required product hinting the composition of initial charge and changing with comparing for the preparation of the composition of before-mentioned products, then be necessary to consider the residual of before-mentioned products in the stove.Yet, those skilled in the art will know that and how correspondingly regulate initial charge.

At step b ₁') in, preferably in arc furnace, initial charge is melted.Electric smelting makes it possible to the standby a large amount of particles of favourable efficiency system.

For example, can use Heroult type arc furnace, this arc furnace has two electrodes and has the container that about 0.8 meter (m) diameter also can hold about 180kg melt liquid.Voltage is preferably 140V-180V, and power is about 240 kilowatts (kW), and energy is 1150kWh/t-2800kWh/t.

Yet, can expect all known stoves, for example the Heroult stove of induction furnace, plasma furnace or other type needs only them and can make the complete melting of initial charge.And so nonessential, can also by described in the FR 1 208 577, improve the stirring quality by carrying out bubbling with oxidizing gas (for example air or oxygen).Particularly can improve the quality that melt liquid is stirred by carrying out bubbling with the gas that comprises 35 volume % oxygen.

At step b ₁') when finishing, all initial charge is liquid form.

At step c ₁') in, will be in and be preferably greater than 1600 ℃ and preferably less than 2200 ℃, the melt liquid material stream that is more preferably less than 1800 ℃ temperature when element is strontium is dispersed into the droplet form.

Can jet and pass melt liquid material stream and produce dispersion.Yet can expect any other method of atomized molten liquid well known by persons skilled in the art.

In steps d ₁') in, by with oxygen-bearing fluid, preferred gas more preferably contacts with air and/or steam and changes drop into solid particle.Oxygen-bearing fluid preferably contains at least 20 volume % or even the oxygen of at least 25 volume %.

The method is modulated, so that the drop of melt liquid contacts with oxygen-bearing fluid when forming at once.More preferably, disperse (step c ₁') and solidify (steps d ₁') be substantially simultaneously, described melt liquid disperses by the oxygen-bearing fluid that is suitable for making this liquid cools and solidify.

Preferably, do not use except by contact the solidification mode cooling off with oxygen-bearing fluid.Therefore, for example preferably do not use the drop with melt liquid to face toward the super quenching method that the cool metal wall sprays.

Air under the winding-up room temperature is fully suitable.

Cooldown rate is the dependent variable of particle diameter.Be about 1000K/s for this speed of the particle with 0.3mm size.Preferably cooldown rate is regulated so that particle with before returnable contacts at least in their hardening of peripheral region.

In steps d ₁') when finishing, obtaining solid particle of the present invention, described particle has the size of 0.01mm-3mm or 0.01mm-4mm according to dispersion condition.

Advantageously, in unexpected and unaccountable mode, melt liquid is contacted the LTM perovskite that makes it possible to obtain with low cost commercial quantities with oxygen-bearing fluid, outside the removal of impurity, the percentage of this LTM perovskite is outstanding, reach greater than 90% and even greater than 99.9%, and need not annealing steps.

At optional later step e ₁') in, the consolidation particle is introduced in the stove with the heat treatment of annealing.Advantageously, such annealing can further improve the percentage of LTM perovskite.Therefore, this makes it possible to obtain substantially to equal 100% LTM perovskite percentage (outside the removal of impurity).

Annealing temperature is preferably 1050 ℃-1400 ℃, more preferably 1100 ℃-1200 ℃ and also preferred about 1150 ℃.This temperature preferably kept being longer than 0.5 hour, preferably was longer than 2 hours and was preferably about 5 hours duration.Preferably under the atmosphere that contains at least 20 volume % oxygen, preferably under air, be preferable over the heat treatment of annealing under the ambient pressure of about 1 bar.

Consolidation particle of the present invention can be ground before or after annealing.In case of necessity, can be depending on the expectation application and carry out the selection of particle size.

Particle of the present invention can advantageously show various yardsticks, and the preparation method is not limited to obtain the perovskite powder of sub-micron sized.Therefore it is very suitable for the industry preparation.

At first, in blender, following initiation material is closely mixed:

By the CaO powder that supplier La Gloriette sells, this powder has greater than the purity of 93 % by weight and has the underflow that 80 μ m sieve that pass through greater than 90%; With

The initial charge of the heavy 50kg that obtains is by this way poured in the Heroult type electrometal furnace.Then use the long arc fusing with its melting (voltage is 150V, and power is 225kw, and the energy that applies in an embodiment is that 1380kWh/t-2000kWh/t does not wait), in order to melt entire mixture in complete and uniform mode.Condition of work is oxidizability.

In case fully fusing casts melt liquid in order to form material stream.The temperature that records melt liquid during the casting is 1730 ℃-1850 ℃.

Then the dried compressed air under the environment for use temperature, and jet with 1 bar-3 bar pressure, be dispersed into drop with broken material stream and with this melt liquid.

The air of winding-up cools off drop and they is condensed with the consolidation particle form.Depend on the air blown condition, the consolidation particle can be made sphere or other form, can be hollow or solid.They have the size of 0.01mm-3mm or 0.01mm-4mm.

The sample that has after grinding less than 40 μ m median size is carried out chemical analysis and lanthanum-strontium-manganese Perovskite Phase mensuration.

Carry out chemical analysis with x-ray fluorescence.

Use x-ray diffraction pattern to measure the percentage of lanthanum-strontium-manganese perovskite, described diffraction pattern is obtained by the D5000 diffractometer that is equipped with copper DX pipe from supplier Bruker.After consolidation, other La for example mutually that products obtained therefrom can comprise Perovskite Phase and small amount ₂MnO ₄

Use joint committee (ICDD) card, adopt conventional criterion to determine lanthanum-strontium-manganese Perovskite Phase by X-ray diffraction.For example, ICDD 01-089-8084 card is for La _0.7Ca _0.3MnO _3-δThe card of lanthanum-calcium-manganese Perovskite Phase.

In fact, when showing below, x-ray diffraction pattern carries out the measurement of lanthanum-calcium-manganese perovskite percentage:

Main lanthanum-calcium-manganese Perovskite Phase; With

Inferior looks and other possible less important phase.

Then, with EVA software (being sold by supplier Bruker) and after deduction continuous background (background 0.8), can measure the main diffraction maximum of lanthanum-calcium-manganese perovskite or area (without the deconvolution processing) A of multiplet _LTMWith the main diffraction maximum of inferior looks or the area A of multiplet _{Inferior looks}(without deconvolution processing).Then use formula (1) to calculate the percentage of lanthanum-calcium-manganese perovskite.

Therefore, if lanthanum-calcium-manganese (LCM) Perovskite Phase is the unique phase that exists in the x-ray diffraction pattern, then perovskite percentage equals 100%.

Table 4 has gathered the result who obtains before any annealing heat treatment.

Table 4

Table 4 has shown the validity of the inventive method.

Then under the condition product of embodiment 6 is heat-treated below:

Temperature: 1150 ℃;

Soaking time under this temperature: 5 hours;

Atmosphere: the air under the atmospheric pressure (ambient pressure).

After heat treatment, outside the removal of impurity, this product has lanthanum-calcium of 100%-manganese perovskite percentage.

Can be clear that in this point, method of the present invention in its first broad sense embodiment so that simply and at an easy rate prepare the particle of commercial quantities, described particle has very high lanthanum-element T-manganese perovskite level, and wherein element T is the element that is selected from strontium, calcium, magnesium, barium, yttrium, ytterbium and cerium.

Especially, the method make it possible to preparation by greater than 99.9% or even the particle that consists of of 100% (outside the removal of impurity) lanthanum-element T-manganese perovskite, described perovskite has formula (La _1-xT _x) _1-yMnO _3-δ, wherein 0＜x≤0.5 and-0.1≤y≤0.24.

Purposes such as fruit product needs, and then then can subtract short grained yardstick, for example forms powder by they are ground.

The below describes the method for the second broad sense embodiment of the present invention in detail.

At step a ₂') in, press above with regard to step a ₁') described preparation initial charge, step a ₂') and step a ₁') have an identical preferred characteristics.

At step b ₂') in, initial charge is melted.Can use any melting furnace.Can be by relating to step b ₁') description in or preferably above relate to step b ₂) description in illustrated the fusing.Especially, step b ₂) description the advantage of using induction furnace has been described.

At step b ₂') when finishing, all initial charge is liquid form.

At step c ₂') in, press above with regard to step c ₂) illustrated, melt liquid is cast in the mould.Described casting melt liquid has and is preferably greater than 1600 ℃ and preferably less than 2200 ℃ temperature, is more preferably less than 1800 ℃ temperature when element T is strontium.

In steps d ₂') in, press above with regard to steps d ₂) described, the liquid that is cast in the mould is cooled off, until obtain at least part of block that solidifies, steps d ₂') have and steps d ₂) identical preferred characteristics, described characteristic is particularly related to and the contacting of oxygen-bearing fluid, cooling rate and the type of cooling.

Advantageously, in unexpected and unaccountable mode, melt liquid is contacted to improve significantly LTM perovskite percentage in the consolidation block of the present invention with oxygen-bearing fluid, reach basic 100%.Thereby, need not annealing steps and obtain such percentage.

In addition, the inventor finds that the cooldown rate of solidificating period is not to improve the deciding factor of LTM perovskite percentage.Advantageously, thereby can use simple conventional cooling means.

At step e ₂') in, press above with regard to step e ₂) illustrated, with the block demoulding, step e ₂') have and step e ₂) identical preferred characteristics, the situation that described characteristic is particularly related to the demoulding and contacts with oxygen-bearing fluid.

At optional step f ₂') in, press above with regard to step f ₂) illustrated, the block of the demoulding is put into stove with the heat treatment of annealing, step f ₂') have and step f ₂) identical preferred characteristics, described characteristic is particularly related to annealing parameter.

Advantageously, such annealing can significantly improve LTM perovskite percentage.Therefore outside the removal of impurity, can obtain greater than 99%, be preferably greater than 99.9% and even substantially equal 100% LTM perovskite percentage, and, even any melt liquid can not be contacted with oxygen-bearing fluid, for example because the preparation block when the demoulding, solidified fully and in mould cooling period or casting during can not contact with oxygen-bearing fluid, also can be able to like this.

In order for example to obtain the powder for the preparation of the negative electrode of Solid Oxide Fuel Cell (SOFC), optionally subsequently the block of annealing is pulverized and be ground to required particle size.Advantageously, method of the present invention makes it possible to prepare the particle with various yardsticks, and expense is low.

Preferably, at first the block of the demoulding is pulverized into the sheet of 0-5mm.Then to the described heat treatment of annealing, subsequently it is ground to required particle size.

Provide for illustration purposes following embodiment, described embodiment does not limit the present invention.The block for preparing as follows test.

At first, the initiation material identical with employed those initiation materials among the embodiment of the first broad sense embodiment that relates to this particle closely mixed in blender.

The gained initial charge is poured in the Heroult type electrometal furnace (except embodiment 6 ₂' outer).Then melt with its melting (voltage is 180V, and the energy that applies does not wait for 1150kWh/t-1760kWh/t between embodiment), in order to melt entire mixture by complete and uniform mode by long arc.Operating condition is oxidizability.

In case fusing is cast to melt liquid in the cast iron die in air fully.The temperature that records melt liquid during the casting is 1560 ℃-1700 ℃.

By mentioned above cooldown rate " Vr " is assessed (seeing Table 2).

The sample that has after grinding less than 40 μ m median size is carried out chemical analysis and lanthanum-calcium-manganese Perovskite Phase mensuration.

Carry out chemical analysis with x-ray fluorescence.

By with the first broad sense embodiment (seeing Table 4) in identical mode, determine lanthanum-calcium-manganese Perovskite Phase and measure their percentage.

Table 5 has gathered the result who obtains before any annealing heat treatment.

Between melting stage, do not blast gas.

Embodiment 6 ₂' relating to by making the with the following method block of preparation: described method utilization is according to the induction melting of FR 1 430 962, and the diameter of wire turn is 275mm, and power is 120kW-220kW, and the frequency that the aperiodicity generator provides is 100kHz-250kHz.

Table 5

Embodiment

Voltage (V)

The energy that applies (kWh/t)

The quality (kg) of the charging of fusing)

Mould-type

Vr (℃/s)

The yardstick (mm) of casting block

1 ₂’

180

1400

50

Cast iron

＜0.1

D200，h150

2 ₂’

180

1400

50

Cast iron

＜0.1

D200，h150

3 ₂’

180

1760

50

Cast iron

＜0.1

D200，h150

4 ₂’

180

1150

40

Cast iron

＜0.1

D200，h150

5 ₂’

180

1700

40

Cast iron

＜0.1

D200，h150

6 ₂’

-

75

The wire turn of coil

＜0.1

D275，h190

In following table 5 ', the content of elements La is with La ₂O ₃The form meter, the content of element calcium is in the CaO form, and the content of element manganese is in the MnO form.

Table 5 '

Table 5 ' shown the validity of the inventive method.This table shows that also (embodiment 6 when melting by induction ₂'), wherein the surface of demoulding block contact with airborne oxygen quickly (in this embodiment from solidify begin at the most after 20 minutes, this moment, block solidified not yet fully), the percentage of lanthanum-calcium in the final products-manganese perovskite is very high, reach 99.9%, therefore advantageously so that the heat treatment of annealing becomes nonsensical.

Subsequently to embodiment 1 ₂', 2 ₂', 3 ₂' and 5 ₂' heat treatment (table 6) of annealing.Casting block or the block that is crushed to the 0-5mm sheet annealed, and (embodiment 1 in heat treatment ₂' and 2 ₂').In table 6, provided employed heat treatment parameter.In air, heat-treat.

According to relate to the LTM particle, be particularly related to lanthanum-calcium-mode in above-described embodiment of manganese particle measures LTM perovskite percentage.

Table 6

Table 6 shows that annealing in process causes lanthanum-calcium-manganese perovskite percentage to significantly improve, up to basic 100%.

Can be clear that, the method of the second broad sense embodiment according to the present invention is so that simply and at an easy rate prepare the block of commercial quantities, described block has very high-caliber lanthanum-element T-manganese perovskite, and wherein element T is the element that is selected from strontium, calcium, magnesium, barium, yttrium, ytterbium and cerium.

Especially, the method make it possible to preparation by greater than 99.9% or even the block that consists of of the lanthanum-element T of 100% (outside the removal of impurity)-manganese perovskite, this lanthanum-element T-manganese perovskite has formula (La _1-xT _x) _1-yMnO _3-δ, wherein 0＜x≤0.5 and-0.1≤y≤0.24.

When element T was calcium, this method was so that can prepare especially the block that contains lanthanum-calcium-manganese (LCM) perovskite, wherein:

" with La ₂O ₃The lanthanum of form meter " percentage by weight greater than 40.2%, be preferably greater than 43.3%, be preferably greater than 51.8%, more preferably greater than 56.8%, and/or less than 70.8%, preferably less than 69.9%, preferably less than 68.9%, be more preferably less than 63.6%; And/or

The percentage by weight of " in the calcium of CaO form " is preferably greater than 3.7% greater than 0.44%, and/or less than 16.1%, preferably less than 15.6%, preferably less than 10%, is more preferably less than 6.8%; And/or

The percentage by weight of " in the manganese of MnO form " is preferably greater than 29.6% greater than 28.7%, is preferably greater than 30.6%, more preferably greater than 32.6%, and/or less than 46%, preferably less than 41.8%, preferably less than 38.6%, is more preferably less than 36.6%.

If the purposes of block needs, then then can reduce their yardstick, for example by being ground, they form powder.

Consolidation LTM perovskite product is outstanding especially, and reason is, uses the La of the measured generation of above-mentioned criterion ₂Zr ₂O ₇The amount of pyrochlore-type phase is with the La that uses the LTM perovskite powder that obtains by the method outside the consolidation to produce under the same conditions ₂Zr ₂O ₇The amount of pyrochlore-type phase is compared, and is always lower.This performance even it seems the feature that will consist of product of the present invention.

The following is for the method for measuring this performance.

The LTM perovskite powder that ten grams (g) is used for test closely mixes with 8 % by mole of yttria stabilized zirconia powder with 10g, and described LTM perovskite powder has the median size less than 1.5 μ m.Then being included in 1375 ℃ of lower cycles of 24 hours of soaking, under high temperature, the sheet grain of this mixture is suppressed and sintering.Measure median size and the sintering heat treatment parameter of LTM powder, in order to help to form La ₂Zr ₂O ₇The pyrochlore-type phase, thus outstanding LTM powder is in they the behavior difference when contacting with 8 % by mole of yttria stabilized zirconia powder.

Measure the La that comprises in the sintered sample by X-ray diffraction ₂Zr ₂O ₇The amount of pyrochlore-type phase is with respect to La in the sample ₂Zr ₂O ₇Pyrochlore-type phase and zirconic total amount represent.Therefore this measurement is measurement of comparison, is not quantitative measurment.

When carefully using identical criterion and identical stabilized zirconia powder, can be easy to carry out the contrast between the Different L TM perovskite powder.Preferably, all samples carries out sintering in identical stove, so that any residual quantity that restriction may cause because of the preparation method of sample to be characterized.

Embodiment

Test below carrying out is so that explanation consolidation perovskite product at high temperature produces less La when being contacted by stable Zirconium oxide powder ₂Zr ₂O ₇The ability of phase.

Described test comprises Zirconium oxide powder is closely mixed with lanthanum-manganese (LTM) perovskite powder of doping that then preparation sheet grain rises to high temperature to promote La ₂Zr ₂O ₇The generation of phase.Then measure the described amount with respect to zirconia amount in the sample that produces by X-ray diffraction.

At length, use following method.

As follows for the preparation of the sample that comprises the LTM powder that contrasts.

In glass beaker, use the stainless steel spatula sold 10g by supplier Tosoh TZ-8Y Zirconium oxide powder (with 8 % by mole of stabilized with yttrium oxide and have 0.212 a μ m median size d ₅₀(recording with the sedimentation grain size analysis method) and 15.2m ²The zirconia of/g specific area) mixes for one of LTM perovskite powder that contrasts with 10g, until color is even, described LTM perovskite powder has the median size of 0.16-1.1 μ m, choose wantonly after using zirconia bead with 16.5 % by mole of ceria stabilized to grind in LME (1) type Netzsch mill, described zirconic bead has the particle size of 0.8mm-1mm.Then spiece is transferred in the agate mortar to use the agate mortar hand lapping, then in glass beaker, with the stainless steel spatula all powder is mixed again.

Then use the preparation of sheet grain press to have the sheet grain of 13mm diameter and basic 5mm thickness: the 2.8g powder to be put into wherein and suppressed 1 minute under 50,000 Ns (KN) with manual Weber press.

Then the sheet grain is placed on the aluminium saggar with lid.

This assembly is put in Naber 1800 stoves of being sold by supplier Nabertherm, then be warming up to 1375 ℃ and kept 24 hours, with 5 ℃ of/minute intensifications and with 5 ℃ of/minute coolings.

Then make sheet grain attenuate in mill of each sintering manifest thus the core of material in order to remove the thickness of about 2mm.At last the sheet grain is applied and polishes with transparent resin.

Use realizes the X-ray diffraction measurement from the D5000 device that is equipped with copper DX pipe of supplier Bruker.Produce x-ray diffraction pattern with 0.02 ° step-length and the acquisition time in 4 seconds per steps.In fact, these figure make it possible to detect:

La ₂Zr ₂O ₇The pyrochlore-type phase locates to have its diffracted primary peak (ICDD card 00-017-0450) 28.7 ° of 2 θ ≈; With

The cubic zirconia phase locates to have its diffracted primary peak (ICDD card 00-027-0997 or 01-049-1642) 30.5 ° of 2 θ ≈.

Then use EVA software (being sold by supplier Bruker) and after deduction continuous background (background 0.8), can measure La ₂Zr ₂O ₇The peak area of pyrochlore-type in 28.4 °＜2 θ＜29.1 ° angular ranges and the peak area of cubic zirconia in 29.3 °＜2 θ＜30.8 ° angular ranges.

Provide the result with following ratio form:

The various LTM perovskite powder that contrast are as follows:

-by the method beyond the consolidation for example synthetic by solid-phase sintering, by the synthetic of precursor and contrast prior art powder that spray pyrolysis obtains:

By (lanthanum of doping strontium) and the perovskite powder of manganese of supplier NexTech Materials with title LSM20-P sale; Hereinafter referred to as " Comparative Examples 1 ";

By supplier Praxair with title (La _0.8Sr _0.2) _0.98(lanthanum of doping strontium) and the perovskite powder of manganese that the Mn oxide is sold; Hereinafter referred to as " Comparative Examples 2 "; With

The applicant is by comprising the La that carries out sintering in 1450 ℃ of lower cycles of 10 hours of soaking ₂O ₃, SrCO ₃And MnO ₂The immixture of powder hereinafter is called " Comparative Examples 3 " by solid-phase sintering synthetic (lanthanum of doping strontium) and the perovskite powder of manganese;

The powder of-consolidation perovskite product of the present invention:

The perovskite powder of consolidation of the present invention (lanthanum of doping strontium) and manganese is called above that " embodiment 1 ₂", it is not carried out any annealing in process (seeing Table 2 ');

Preamble is called that " embodiment 1 ₂" consolidation of the present invention (lanthanum of doping strontium) and the perovskite powder of manganese, in air, under 1150 ℃, with soaking in 5 hours it is carried out annealing in process (seeing Table 3);

Be called above that " embodiment 1 ₁" consolidation of the present invention (lanthanum of doping strontium) and the perovskite powder of manganese, it is not carried out any annealing in process (seeing Table 1);

Be called the consolidation of the present invention (lanthanum of doping strontium) of " embodiment A " and the perovskite powder of manganese, it does not carried out any annealing in process; With

Be called the consolidation of the present invention (lanthanum of doping calcium) of " Embodiment B " and the perovskite powder of manganese, it does not carried out any annealing in process.

These perovskites have following chemical composition:

Table 7

Embodiment	Form
		Comparative Examples 1	(La _0.8Sr _0.2) _0.99MnO _3-δ
Comparative Examples 2	(La _0.8Sr _0.2) _0.98MnO _3-δ
		Comparative Examples 3	(La _0.81Sr _0.19) _0.99MnO _3-δ
A	(La _0.64Sr _0.36)MnO _3-δ
		B	(La _0.79Ca _0.21)MnO _3-δ

As indicated above, by each these powder with prepared the sheet grain by stable zirconic mixture.

Table 8 has gathered with regard to the determined measurement scale of each sample that makes:

Table 8

Table 8 clearly illustrates, the powder of consolidation perovskite product of the present invention is compared with the powder of prior art perovskite product by the method gained outside the consolidation, has relatively little a lot of ratio:

In product of the present invention, even may can't detect La ₂Zr ₂O ₇The pyrochlore-type phase.

Therefore, advantageously, use the performance of the Solid Oxide Fuel Cell of these products to improve.

In addition, (embodiment 1 for Fig. 8 ₂) show that annealing steps does not change the favourable behavior of product of the present invention.Therefore, after annealing, product of the present invention keeps being different from Comparative Examples.

As indicated above, the LTM perovskite product is when contacting with zirconia, and they can also produce disadvantageous T _aZr _bO _cThe type phase, a, b and c are integers.As by as shown in the following embodiment, each T _aZr _bO _cThe amount of type phase is based on this T _aZr _bO _cThe total amount meter of type phase and cubic zirconia, for consolidation product of the present invention all the time less than for the non-consolidation product according to prior art.

Be used for measuring T _aZr _bO _cThe method of the amount of type phase is similar to that preamble describes is used for measuring La ₂Zr ₂O ₇The method of the amount of pyrochlore-type phase.

For example, when the element T of LTM perovskite is strontium (Sr), records this and be mutually SrZrO ₃X-ray diffractogram shows:

SrZrO ₃The type phase has its main peak 30.8 ° of 2 θ ≈;

The cubic zirconia phase has its main peak (ICDD card 00-027-0997 or 01-049-1642) 30.5 ° of 2 θ ≈.

Then use EVA software (being sold by supplier Bruker) and after deduction continuous background (background 0.8), can measure SrZrO ₃The peak area of type in 30.5 °＜2 θ＜31.2 ° angular ranges and the peak area of cubic zirconia at 29.3 °＜2 θ＜30.8 ° angular ranges.

Provide the result with following ratio form:

The below has provided the various LSM perovskite powder that compare:

The applicant is by comprising the La that carries out sintering in 1450 ℃ of lower cycles of 10 hours of soaking ₂O ₃, SrCO ₃And MnO ₂The immixture of powder hereinafter is called " Comparative Examples 4 " by (lanthanum of doping strontium) and the perovskite powder of manganese of the synthetic contrast of solid-phase sintering;

Be called the consolidation of the present invention (lanthanum of doping strontium) of " Embodiment C " and the perovskite powder of manganese, it does not carried out any annealing in process.

These perovskites have following chemical composition:

Table 9

Embodiment	Form
		Comparative Examples 4	(La _0.63Sr _0.37)MnO _3-δ
C	(La _0.63Sr _0.37)MnO _3-δ

Table 10 has gathered with regard to the determined ratio of the sample of each preparation " area (SrZrO ₃)/(area (SrZrO ₃)+area (cubic zirconia)) " measurement result.

Table 10

Embodiment	Area (SrZrO ₃)/(area (SrZrO ₃)+area (cubic zirconia)) ratio
		Comparative Examples 4	0.068
C	0

Table 10 clearly illustrates, the powder of LSM perovskite consolidation product of the present invention is compared with the powder of perovskite product by the other method gained beyond the consolidation, has relatively little a lot of area (SrZrO ₃)/(area (SrZrO ₃)+area (cubic zirconia)) ratio.In product of the present invention, even may can't detect SrZrO ₃Phase.

Advantageously, use the performance of the Solid Oxide Fuel Cell of these products therefore to be improved.

Certainly, the invention is not restricted to described embodiment, described embodiment provides with illustrative and non-limiting example.

Especially, product of the present invention is not limited to any specific shape or yardstick.

Claims

1. the consolidation product that comprises the LTM perovskite, L refers to lanthanum, T is the element that is selected from the mixture of strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and these elements, and M refers to manganese, this product has thickness greater than bulk shape or the grain shape of 1mm, wherein said consolidation product obtains by the following method, and described method comprises the fusing initial charge to obtain the step of melt liquid, is that the described melt liquid of cooling is until its step of solidifying fully subsequently.

2. according to the consolidation product of last claim, described perovskite has respectively the molar ratio l of lanthanum, element T and manganese _p, t _pAnd m _p, so that be denoted as:

X=t _p/ (l _p+ t _p) and y=1-(l _p+ t _p)/m _p

Then: x＞0 and x≤0.5; With

Y 〉=-0.1 and y≤0.24.

3. according to the consolidation product of last claim, 0＜x≤0.4 wherein.

4. according to the consolidation product of last claim, wherein:

X＞0.02 and x＜0.35; And/or

·-0.05≤y≤0.1。

5. according to the consolidation product of last claim, 0.02＜x≤0.3 wherein.

6. according to the consolidation product of last claim, wherein:

0.15＜x＜0.25; And/or

·0≤y≤0.1。

7. according to claim 1 consolidation product, this consolidation product has the LTM perovskite percentage greater than 50% outside the removal of impurity.

8. according to the consolidation product of last claim, wherein outside the removal of impurity LTM perovskite percentage greater than 90%.

9. according to the consolidation product of last claim, wherein outside the removal of impurity LTM perovskite percentage greater than 99%.

10. according to the consolidation product of last claim, wherein outside the removal of impurity LTM perovskite percentage greater than 99.9%.

11. according to the consolidation product of last claim, described perovskite is formula (La _1-xSr _x) _1-yMnO ₃Lanthanum-strontium-manganese perovskite, wherein 0＜x≤0.5 and-0.05≤y≤0.24, x and y are atomic ratio.

12. according to the consolidation product of last claim, in the formula of wherein said lanthanum-strontium-manganese perovskite:

(0＜x＜0.5) and (0≤y≤0.1).

13. according to the consolidation product of last claim, in the formula of wherein said lanthanum-strontium-manganese perovskite:

(0.15＜x＜0.35)。

14. according to the consolidation product of last claim, in the formula of wherein said lanthanum-strontium-manganese perovskite:

0.15＜x＜0.25。

15. consolidation product according to claim 1, element T are the lanthanum dopants that is selected from calcium, strontium, barium, magnesium and composition thereof.

16. according to the consolidation product of last claim, employed element T is calcium and/or strontium.

17. according to the consolidation product of last claim, it has following chemical composition by weight percentage, and altogether 100%:

36%＜with La ₂O ₃The lanthanum of form meter＜70.7%;

0%＜in the strontium of SrO form＜25.8%;

29.3%＜in the manganese of MnO form＜41.2%; With

Impurity＜0.7%.

18. according to the consolidation product of last claim, it has following chemical composition by weight percentage, and altogether 100%:

38.4%＜with La ₂O ₃The lanthanum of form meter＜69.7%;

0%＜in the strontium of SrO form＜25.4%;

30.3%＜in the manganese of MnO form＜37.2%; With

Impurity＜0.7%.

19. according to the consolidation product of last claim, it has following chemical composition by weight percentage, and altogether 100%:

47.9%＜with La ₂O ₃The lanthanum of form meter＜69.7%;

0%＜in the strontium of SrO form＜17%;

30.3%＜in the manganese of MnO form＜35.7%; With

Impurity＜0.7%.

20. according to the consolidation product of last claim, it has following chemical composition by weight percentage, and altogether 100%:

47.9%＜with La ₂O ₃The lanthanum of form meter＜61.6%;

6.7%＜in the strontium of SrO form＜17%;

31.5%＜in the manganese of MnO form＜35.7%; With

Impurity＜0.7%.

21. according to the consolidation product of last claim, it has following chemical composition by weight percentage, and altogether 100%:

53.9%＜with La ₂O ₃The lanthanum of form meter＜61.6%;

6.7%＜in the strontium of SrO form＜11.8%;

31.5%＜in the manganese of MnO form＜34.7%; With

Impurity＜0.7%.

22. consolidation product according to claim 1, after cooling not to its anneal heat treatment and/or itself and without any grinding.

23. consolidation product according to claim 1, it is the block form that has greater than 5cm thickness.

24. according to the consolidation product of last claim, it is the block form that has greater than 15cm thickness.

25. consolidation product according to claim 1, it is particle form, and its sphericity is greater than 0.5.

26. according to the consolidation product of last claim, described particle has the size less than 4mm.

27. consolidation product according to claim 1, it can obtain by method according to claim 28.

28. comprise the preparation method of the consolidation product of LTM perovskite, L refers to lanthanum (La), T is the element that is selected from the mixture of strontium, calcium, magnesium, barium, yttrium, ytterbium, cerium and these elements, and M refers to manganese (Mn), and the method comprises following step:

A ') will provide the raw material of lanthanum, element T and manganese to mix, to form initial charge;

B ') this initial charge is melted to obtain melt liquid;

C ') cool off this melt liquid until it solidifies fully, in order to obtain the consolidation product, this consolidation product has thickness greater than bulk shape or the grain shape of 1mm.

29. according to the method for last claim, wherein determine the amount of lanthanum, element T and manganese in the initial charge, so that at step c ') the consolidation product that obtains when finishing meets in the claim 22 to 26 each.

30. method according to claim 29, wherein provide the compound of element L, T and M account for altogether the initial charge composition greater than 90 % by weight.

31. according to the method for last claim, wherein provide the compound of element L, T and M account for altogether the initial charge composition greater than 99 % by weight.

32. according to the method for last claim, wherein provide the compound of element L, T and M and 100 % by weight that impurity accounts for the initial charge composition altogether.

33. method according to claim 28 wherein provides the compound of element L, T and M to be selected from: SrO; SrCO ₃La ₂O ₃CaO; CaCO ₃Y ₂O ₃Yb ₂O ₃MgO; MgCO ₃CeO ₂BaO; MnO ₂MnO or Mn ₃O ₄

34. method according to claim 28, wherein element L, T and M divide other molar ratio l _d, t _dAnd m _d, in based on ratio l _d, t _dAnd m _dThe molar percentage of total amount meter, condition below satisfying:

k ₁. (1-x). (1-y)≤l _d/ m _d≤ k ₂. (1-x). (1-y) (1) and/or

k ₁.x.(1-y)≤t _d/m _d≤k ₂.x.(1-y) (2)

Wherein 0＜x≤0.5 and-0.1≤y≤0.24, k ₁Equal 0.8, k ₂Equal 1.2.

35. according to the method for last claim, wherein k ₁Equal 0.9, and k ₂Equal 1.1.

36. method according to claim 28 is wherein at step b ') in, when being particle form, uses the consolidation product arc furnace, perhaps when being block, uses the consolidation product induction furnace.

37. method is according to claim 28 wherein annealed the consolidation product.

38. the method according to last claim, wherein anneal under the soaking temperature in 1050 ℃ of-1400 ℃ of scopes, all thermal endurance is at least 30 minutes under this temperature, when the consolidation product is block form, in case all the consolidation product reaches soaking temperature, just begins soaking.

39. method is according to claim 37 wherein annealed under the atmosphere that contains 20 volume % oxygen at least.

40. method according to claim 28, wherein step c ') comprise following step:

c ₁') melt liquid is dispersed into the drop form; With

41. method according to claim 40 is wherein at step c ') in, described melt liquid is contacted with oxygen-bearing fluid.

42. method according to claim 40 is wherein at step c ₁') and/or steps d ₁') in, described melt liquid is contacted with the oxygen-bearing fluid that contains 20 volume % oxygen at least.

43. method according to claim 40, wherein dispersion steps and coagulation step are simultaneously.

44. method according to claim 40 wherein keeps the contact between drop and the oxygen-bearing fluid, until described drop solidifies fully.

45. method according to claim 28, wherein step c ') comprise following step:

c ₂') melt liquid is cast in the mould;

e ₂') with the described block demoulding.

46. according to the method for last claim, at step c ₂') in and/or in steps d ₂') in and/or at step e ₂') after, the melt liquid that is solidifying is directly or indirectly contacted with oxygen-bearing fluid.

47. according to the method for last claim, wherein oxygen-bearing fluid is gas.

48. method according to claim 46, wherein oxygen-bearing fluid is air.

49. method according to claim 46 wherein begins described contact at once after with the block demoulding.

50. method according to claim 46 wherein keeps this contact until block solidifies fully.

51. method according to claim 45, wherein implementation step e before block solidifies fully ₂') the demoulding.

52. method according to claim 45, in case just it is carried out the demoulding when wherein block has the rigidity that is enough to substantially to keep its shape.

53. method according to claim 45, wherein the cooldown rate of the melt liquid of solidificating period is all the time less than 1000K/s.

54. method according to claim 45 is wherein after the optional annealing, with the broken in blocks or powder of the block of the demoulding.

55. the consolidation product of claim 1 or the method by according to claim 28 obtain the purposes of consolidation product in the negative electrode preparation of Solid Oxide Fuel Cell that maybe can obtain.

56. consolidation product, comprise the LTM perovskite, L refers to lanthanum, T refers to magnesium and randomly is mixed with one or more elements that are selected from strontium, calcium, barium, yttrium, ytterbium, the cerium, and M refers to manganese, wherein said consolidation product obtains by the following method, and described method comprises the fusing initial charge to obtain the step of melt liquid, is that the described melt liquid of cooling is until its step of solidifying fully subsequently.