CN104308140B - A kind of removal is containing the method for silicon in Si cage compound and silicon-containing compound dephasign - Google Patents

Abstract

Removal, containing the silicon comprising in Si cage compound and a method for silicide dephasign, belongs to field of material preparation. Its step is the molecular formula containing Si cage compound according to pre-synthesis, weighs high purity elemental element as raw material. Smelt sample according to conventional method. Grind also ball milling and smelt the alloy obtaining. Powder after use aqueous slkali soaking ball milling 12 hours. Filter above-mentioned solution, use watery hydrochloric acid to process and filter the powder obtaining. Again filter, and with the deionized water powder that washing and filtering obtains repeatedly. The powder that dry upper step obtains, obtains target sample. Utilization of the present invention, containing acidproof, the alkaline-resisting feature of Si cage compound, adopts the mode of dipping by lye, effectively removes containing the dephasign silicon in Si cage compound. In conjunction with the method for acid soak, can obtain pure phase containing Si cage compound. The pervasive method of the method dephasign that to be a kind of removal comprise containing Si cage compound.

Description

A kind of removal is containing the method for silicon in Si cage compound and silicon-containing compound dephasign

Technical field

The invention belongs to field of material preparation, relate to a kind of removal containing silicon and silicon-containing compound dephasign in Si cage compoundMethod.

Background technology

The polyhedron cage that cage compound is made up of IV major element and the object atom being comprised in cage formThere is the compound of cage structure. The interatomic sp of IV main group on cage³Electronics hydridization has formed stronger covalent bonding.A little less than interaction between atom on atom and the cage comprising in cage, make it have comparatively loose atom vibration. ThisPlanting architectural characteristic makes cage compound become the thermoelectricity material of " phonon glass-electron crystal " model of a kind of Slack of meeting propositionMaterial (SlackGA.Newmaterialsandperformancelimitsforthermoelectri ccooling[M] .CRCHandbookofThermoelectrics.CRCpress.1995:407). On the one hand due to cage compoundIn complicated single cell structure and cage, the relatively independent mode of vibration of metallic atom uniqueness (is also known as this class atomRattlingatoms) phonon is produced to strong scattering, given the lower thermal conductivity of such material intrinsic; On the other hand, itsElectric conductivity is mainly to realize by the cage mesh network of IV main group atom, and carrier moving is not subject to the metal in cage substantiallyAtom hinders. The combination of this two specific character has just formed high-efficiency thermal electric material desired " phonon glass-electron crystal "Character (MahanG, SalesB, SharpJ.Thermoelectricmaterials:NewapproachestoanOldproblem[J] .PhysicsToday, 1997,50:42-47.). The special crystal structure of cage compound can carriedWhen high material electric conductivity, reduce the thermal conductivity of material, make it have higher conversion efficiency of thermoelectric. Wherein containing Si cage shapeIt is simple that compound has technique, and raw material sources are feature widely, becomes one of thermoelectric material having potential application foreground. Prepare purePhase containing Si cage compound, be the key of exploring containing Si cage compound material. But, containing the preparation of Si cage compoundComponent segregation very easily occurs in journey, and silicon is residual and silicon-containing compound completely in the sample that makes to prepare, to contain a large amount of unreactedsDephasign, has affected the performance of material. Eliminating the dephasign generating in preparation process, is the important means that improves quality of materials. ThereforePeople have studied the method that dephasign is removed. In the middle of cage compound, the cage that covalent networks forms is by alkali metal or alkaline earth goldBelong to and surrounding wherein, this structure makes cage compound all highly stable in air and sour environment. Some dephasigns can be withAcid reaction and being removed. Therefore, acid soak is the means of current conventional removal dephasign. But acid soak only can be removed sampleThe silicide of product neutral and alkali, cannot remove the dephasigns such as elementary silicon. Under many circumstances, while preparing silicon cage compound, unreactedThe content of elementary silicon dephasign is quite a lot of completely. How effectively to remove unreacted completely residual the and silicon-containing compound of silicon be anxiousMajor issue to be solved. For example, the Ba of superconduction₈Si₄₆Be a high pressure phase, synthetic this material normally utilizes HTHPSynthetic technology completes, to equipment requirement harshness, and cannot large-scale production. And utilize conventional electric arc furnace smelting, but can not give birth toBecome superconduction cage compound Ba₈Si₄₆, products therefrom is BaSi₂Mixture with Si. In order to obtain this class superconduction cage under normal pressureShape compound, can use III main group metal (other elements such as such as Al or Ga etc.) part substitute Si (LiY, GarciaJ,ChenN,etal.SuperconductivityinAl-substitutedBa8Si46clathrates[J].JournalofAppliedPhysics,2013,113:203908；LiY,ZhangR,LiuY,etal.Superconductivityingallium-substitutedBa8Si46clathrates[J].PhysicalReviewB,2007,75:054513；LiY,LiuY,ChenN,etal.Vacancyandcopper-dopingeffectonsuperconductivityForclathratematerials[J] .PhysicsLettersA, 2005,345:398-408.), will be conducive to like thisCage compound forms under normal pressure. And along with increasing of Al content, the percentage of cage shape phase increases, and the content of dephasign subtractsFew. But Al content is more, stronger to the compacting of superconduction, so that final quench. Higher in order to obtain superconducting transition temperatureSample, must reduce Ba₈Al_xSi_46-xThe doping of middle Al. And Al doping is when lower, smelts the sample obtaining and comprise variousDephasign, wherein the content of dephasign Si is large especially. In this case, Si is the dephasign that must eliminate, and at present also not veryEffective method. We have invented a kind of method of alkali cleaning, can effectively Si be removed, simultaneously can be to cage compoundStructure and performance impact, and this new invention can utilize conventional arc melting to synthesize and add follow-up alkaline cleaning procedure,Produce on a large scale all kinds of single-phase cage compounds, promote production and the research of cage compound.

Summary of the invention

Silicon and silicon-containing compound are in the synthetic dephasign containing very easily generating in Si cage compound process, object of the present inventionBe to propose a kind of silicon and silicon-containing compound dephasign effectively removed, obtain the method for single-phase cage compound. The method is removed assortedPhase effect is obvious, and simple, has versatility for dissimilar containing Si cage compound, is specially adapted to IClass, II class, VIII class and IX class are containing the monophase materials preparation of Si cage compound.

Idiographic flow of the present invention is:

(1), according to the molecular formula containing Si cage compound of pre-synthesis, weigh high purity elemental element as raw material;

(2) method is routinely smelted sample;

(3) smelting gained alloy is broken into pieces, in mortar, fully ground;

(4) use the powder after high energy ball mill ball milling, Ball-milling Time is 20～40 minutes;

(5) alkali cleaning: the powder after ball milling is poured in aqueous slkali and soaked 12 hours;

(6) filtering solution, obtains the powder after filtering;

(7) pickling: powder is poured in dilute hydrochloric acid solution, and sufficient agitating solution;

(8) filtering solution, and with the deionized water powder after washing and filtering repeatedly;

(9) dried powder, obtains final sample.

Preferably, in the mechanical milling process of step (3), add deionized water.

Preferably, step (5) is used NaOH solution, and concentration is 0.5mol/L, and every 100ml solution adds 1g powder.

Wherein step (1) is described is divided into four kinds containing Si cage compound, and the first containing Si cage compound molecular formula isA₈Si_46-xM_x, there are the structure of I cage-like shape compound and 0≤x≤16.

The second is A containing Si cage compound molecular formula_xSi_136-yM_y, there is the structure of II cage-like shape compound, and 0 <x≤24,y≥0。

The third is A containing Si cage compound molecular formula₈Si_46-xM_x, there is the structure of VIII cage-like shape compound and 0 < x≤16。

The 4th kind is A8Si25 containing Si cage compound molecular formula_-XMx, has the structure of IX cage-like shape compound, and 0<x≤25。

Described four kinds containing Si cage compound, A be below any one element or its combination: Li, Na, K, Rb, Cs,Fr、Be、Mg、Ca、Sr、Ba、Y、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、La、Lu。

M be following any one element or its combination: Cu, Zn, Ag, Au, Al, Ga, In, Ge, Sn, Fe, Co, Ni, Pt,Sb、Bi、B、As、Hg、Mn、As、Pd、Cd、Bi、P、Rh、P。

Feature and the advantage of this method are:

(1) in conjunction with alkali cleaning and pickling, can remove whole dephasigns, obtain single-phase cage compound. Particularly alkaline solutionCan remove dephasign Si. Completely clean product and other dephasigns are not further cleaned by acid solution again.

(2) chemical reaction process that alkali cleaning adds pickling can be removed dephasign, and structure and character to cage compound does not haveHarmful effect. This is a kind of method of removing safely and effectively dephasign in cage compound.

(3) the method efficiency of removal dephasign is high, and step is simple, and economy is easy to operate.

Brief description of the drawings

Fig. 1 for experience successively electric arc furnace smelting (ARC) (a), sample after ball milling (b), alkali cleaning (c), pickling (d)Ba₈Ga₄Si₄₂X ray diffracting spectrum.

Fig. 2 is Ba₈Al₃Si₄₃The contrast of the X ray diffracting spectrum before and after sample treatment.

Fig. 3 is Ba₈Al₃Si₄₃The temperature variant curve of the intensity of magnetization.

Fig. 4 is Ba₆Eu₂Al₆Si₄₀The contrast of the X ray diffracting spectrum before and after sample treatment.

Detailed description of the invention

Below in conjunction with specific embodiment, technical scheme of the present invention is described further. Only should be understood that these embodimentBe used for illustrating invention and be not used in and limit the scope of the invention.

Embodiment 1

Be Ba for preparing nominal composition₈Ga₄Si₄₂Sample, by proportioning Ba₈Ga₄Si₄₂Weigh each element simple substance, many in raw materialThe loss that adds 5% Ba to cause to make up Ba oxidation. Each simple substance element is placed in to electric arc furnaces, under argon gas atmosphere protectionRepeatedly smelt sample, obtain the little ingot of alloy. Use sand papering to fall the oxide layer of the little ingot surface of alloy, grind alloy with mortar littleIngot. Use RigakuUltimaIV rotary anode diffractometer to carry out X-ray diffraction analysis to the powder after grinding, what obtain spreads outPenetrate collection of illustrative plates as shown in Fig. 1 (a). Except principal phase cage compound, a large amount of dephasign BaSi are generated₂And Si.

In figure, the peak of indexing is Ba₈Ga₄Ge₄₂Diffraction maximum, " * " the silicide BaSi that is designated as₂Diffraction maximum, " ↓ " marksFor the diffraction maximum of dephasign Si.

Powder after grinding is poured in the ball grinder of agate system, added a small amount of deionized water. Use high energy ball mill ballGrind 30 minutes, carry out X-ray diffraction analysis after obtaining a small amount of powder for drying, the diffracting spectrum obtaining is as shown in Fig. 1 (b). This mistakeJourney makes BaSi₂Diffraction maximum substantially disappear, Si content decreases. Ball milling makes grain refinement, and crystal boundary fully exposes. In crystal boundaryDephasign BaSi₂Can react with water BaSi after ball milling₂Diffraction maximum substantially disappear. Meanwhile, BaSi₂Provide alkali with reacting of waterProperty environment, occur to react as follows with Si wherein:Make the Si content after ball millingDecrease. But BaSi in sample₂Content is limited, cannot remove all Si. From diffraction pattern, can find out, through wet ball grindingAfter, still there is the diffraction maximum of higher Si. For Si dephasign is all removed, must additionally add alkaline solution, namely belowAlkali cleaning step.

Press the proportioning of every gram of powder of 100ml solution, the powder after ball milling is poured in the NaOH solution of 0.5mol/L, and filledDivide and stir. Leave standstill after 12 hours and filter, the powder for drying that takes a morsel, carries out X-ray diffraction analysis. The diffracting spectrum obtaining is as Fig. 1(c) shown in. As can be seen from the figure, NaOH solution soaks and has well removed the Si simple substance in sample. Due to the powder after filteringThe product that has been mingled with part Si and NaOH solution in end, comprises spreading out of some unknown impurities in the result of its X-ray diffractionPenetrate peak, as " " marks.

Powder after filtering is poured in dilute hydrochloric acid solution, after fully stirring, filtered, and repeatedly rinse institute by deionized waterThe powder obtaining. With the dry powder that obtains of drying basin, carry out afterwards X-ray diffraction analysis. The diffracting spectrum obtaining is as Fig. 1 (d)Shown in. As can be seen from the figure, after above-mentioned treatment process, cage shape is by intact remaining, and Si, BaSi wherein₂Dephasign is completely removed. Finally obtained pure phase containing Si cage compound.

Embodiment 2

Be Ba for preparing nominal composition₈Al₃Si₄₃Sample, by proportioning Ba₈Al₃Si₄₃Weigh each element simple substance, many in raw materialThe loss that adds 5% Ba to cause to make up Ba oxidation. Smelt according to a conventional method, obtain the X-ray diffractogram of smelting sampleSpectrum is as shown in Fig. 2 (a). As seen from the figure, smelt in the alloy that except comprising principal phase cage compound, also have dephasignBaSi₂And Si. Then carry out the step of ball milling, alkali cleaning, pickling, its detailed experimental implementation process is identical with example 1. PlaceAfter reason, the X ray diffracting spectrum of sample is as shown in Fig. 2 (b). As seen from the figure, the sample after above-mentioned treatment step is pure phase IClass is containing Si cage compound. Through EDS constituent analysis, the actual constituent of directly smelting cage shape phase in the sample that isBa_7.9Al_3.83Si_42.15, after processing, the actual constituent of sample is Ba_7.9Al_3.79Si_42.17. Therefore above-mentioned treatment process can beUnder the constant prerequisite of maintenance cage shape phase constituent and structure, remove the silicon and the silicide dephasign that in sample, comprise.

Under the externally-applied magnetic field of 10Oe, Ba while recording low temperature₈Al₃Si₄₃The temperature variant curve of the intensity of magnetization is as Fig. 3 instituteShow. In the time of 6K, Ba₈Al₃Si₄₃There is the diamagnetic transformation of superconduction. Transition temperature compares Ba₈Si₄₆Lower slightly, prove that Al atom successfully enters crystalline substanceLattice, and alkali cleaning does not affect the physical property of cage shape phase.

Embodiment 3

Be Ba for preparing nominal composition₆Eu₂Al₆Si₄₀Sample, by proportioning Ba₆Eu₂Al₆Si₄₀Weigh each element simple substance, formerIn material, add the loss causing to make up Ba oxidation into 5% Ba. Smelt according to a conventional method, obtain the X ray of smelting sampleAs shown in Fig. 4 (a), by analysis, in the sample of smelting, there is Si, BaSi in diffracting spectrum₂、EuSi₂Deng dephasign. Carry out afterwards ballThe step of mill, alkali cleaning, pickling, its detailed experimental implementation process is identical with example 1. Sample X-ray diffraction after treatmentCollection of illustrative plates is as shown in Fig. 4 (b). As seen from the figure, after above-mentioned treatment step, sample dephasign is removed completely. The method is to removingI class has certain versatility containing the silicon comprising in Si cage compound and the dephasign of silicide.

Claims (7)

1. removal, containing the silicon comprising in Si cage compound and a method for silicide dephasign, is characterized in that comprising following stepRapid:

(1), according to the molecular formula containing Si cage compound of pre-synthesis, weigh high purity elemental element as raw material;

(2) method alloy smelting routinely;

(3) smelting gained alloy is broken into pieces, in mortar, fully ground;

(4) use the powder after high energy ball mill ball milling, Ball-milling Time is 20～40 minutes;

(5) alkali cleaning: the powder after ball milling is poured in aqueous slkali and soaked 12 hours;

(6) filtering solution, obtains the powder after filtering;

(7) pickling: powder is poured in dilute hydrochloric acid solution, and with the continuous agitating solution of glass bar;

(8) filtering solution, and with the deionized water powder after washing and filtering repeatedly;

(9) dried powder, obtains final products.

2. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy and be that described step (5) is used NaOH solution, concentration is 0.5mol/L, and the proportioning of powder and NaOH solution is every 100mlSolution adds 1g powder.

3. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy in the mechanical milling process that is described step (3) and add deionized water.

4. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy and be the described structure containing Si cage compound with I cage-like shape compound, its molecular formula is A8Si46-xMx, and 0≤x≤16；

In molecular formula A be following any one element or its combination: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Y, Ce,Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、La、Lu；

M be following any one element or its combination: Cu, Zn, Ag, Au, Al, Ga, In, Ge, Sn, Fe, Co, Ni, Pt, Sb, Bi,B、As、Hg、Mn、As、Pd、Cd、Bi、P、Rh、P。

5. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy and be the described structure containing Si cage compound with II cage-like shape compound, its molecular formula is AxSi136-yMy, and 0 <x≤24,y≥0；

In molecular formula A be following any one element or its combination: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Y, Ce,Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、La、Lu；

M be following any one element or its combination: Cu, Zn, Ag, Au, Al, Ga, In, Ge, Sn, Fe, Co, Ni, Pt, Sb, Bi,B、As、Hg、Mn、As、Pd、Cd、Bi、P、Rh、P。

6. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy and be the described structure containing Si cage compound with VIII cage-like shape compound, its molecular formula is A8Si46-xMx, and 0 < x≤16；

In molecular formula A be following any one element or its combination: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Y, Ce,Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、La、Lu；

M be following any one element or its combination: Cu, Zn, Ag, Au, Al, Ga, In, Ge, Sn, Fe, Co, Ni, Pt, Sb, Bi,B、As、Hg、Mn、As、Pd、Cd、Bi、P、Rh、P。

7. removal according to claim 1 is containing the silicon comprising in Si cage compound and the method for silicide dephasign, its spyLevy and be the described structure containing Si cage compound with IX cage-like shape compound, its molecular formula is A8Si25-xMx, and 0 < x≤25；

In molecular formula A be following any one element or its combination: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Y, Ce,Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、La、Lu；

M be following any one element or its combination: Cu, Zn, Ag, Au, Al, Ga, In, Ge, Sn, Fe, Co, Ni, Pt, Sb, Bi,B、As、Hg、Mn、As、Pd、Cd、Bi、P、Rh、P。