JPS59182271A - Solid electrolyte and manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solid electrolyte useful as a constituent material of oxygen sensors, fuel cells, and the like.

Conventionally, various isoelectrolytes as described above have been known, but stabilized bismuth oxide and stabilized heavy zirconium are considered to be particularly promising.

Bismuth oxide (Bi) constituting the above stabilized bismuth oxide
As is well known, the high-temperature stable δ phase (cubic system) of 203) has a defective fluorite structure in which % of the oxygen ion (02-) positions are vacancies, and the movement of these acid vacancies It exhibits high ionic conductivity.

This cubic bismuth oxide (δ-Bi20.) is stable at high temperatures but unstable at low temperatures. This is thought to be because the concentration of oxygen vacancies in the δ phase is too high for it to exist stably at low temperatures. Calcium oxide (Ca
Heat treatment at high temperature to δ-B 120s using divalent metal oxides such as O), strontium oxide (sro), and trivalent metal oxides such as yttrium oxide (Y2O2) and yttribium oxide (Yb203) as stabilizers. Make a solid solution with
This metal oxide stabilizes the δ phase down to a low temperature range,
The above-mentioned stabilized bismuth oxide has been made practical.

On the other hand, zirconium oxide (Z r 02) is a high melting point substance, but when a predetermined amount of the above-mentioned low-valent metal oxides such as CaO1Mg01Y and O are dissolved in solid solution as a stabilizer, the temperature reaches its maximum temperature. The fluorite cubic crystal becomes a stable phase up to a low temperature range, and there are many defects (
It was found that the electrical conductivity (ion transfer number) was improved by the formation of vacancies, and the above-mentioned stabilized Δ
There is lysirconium nitride.

By the way, considering the purpose and environment of use, the main characteristics required for solid electrolytes that are not applicable to the above-mentioned fields such as oxygen sensors and fuel cells are (
There are two points: b) the conductivity (ion transfer number) is excellent even in a low temperature range, and (b) the coefficient of thermal expansion is small.

However, in the conventional solid electrolyte mentioned above, Y2O3
Although it is possible to individually satisfy each of the above characteristics to some extent by changing the solid solution amount of stabilizers such as, it is difficult to satisfy both of them at the same time. Also,
At present, its characteristic values are not necessarily satisfactory in practice. In other words, solid electrolytes applied to the above fields are desired to have good electrical properties down to a low temperature range and a small coefficient of thermal expansion.

The present inventors have conducted intensive research to develop a solid electrolyte that satisfies the above-mentioned characteristics at the same time and a method for manufacturing the same, and have come to the following findings.

(a) Stabilizer costs ¥20. The amount of solid solution is about 10m
Stabilized bismuth oxide ((B120s)0 at o79%
,9(Y20s)0.1) and stabilized zirconium oxide ((Zr02)0,9(Y20110,1)).

(b) The above-mentioned stabilized bismuth oxide and stabilized zirconium oxide are made into powders, mixed in a predetermined ratio (stabilized bismuth oxide is about 60 ma 1% or more), and when molded and fired, the above-mentioned stabilized bismuth oxide and stabilized zirconium oxide are mixed. It has better electrical conductivity than zirconium oxide alone. Especially in the low temperature range, the difference is significant.

The present invention has been made based on the above findings. That is, in the present invention, about 5 to 30 m
A first calcination step in which a powdered stabilizer of oe% is mixed and fired to form a stabilized bismuth oxide; A second calcination step in which stabilized bismuth oxide and stabilized zirconium oxide are mixed into a stabilizing agent and fired to form stabilized zirconium oxide, and the stabilized bismuth oxide and stabilized zirconium oxide are powdered and their mixing ratio is determined. , a powder mixing step of mixing stabilized bismuth oxide with a proportion of about 60 mod% or more and stabilized zirconium oxide with a proportion of about 40 mo1% or less, and a main sintering step of molding this powder mixture and firing it. A solid electrolyte manufacturing method is a solid electrolyte obtained by the method.

Next, the present invention will be explained in detail based on its one side. In this example, T31203 powder, ZrO2 powder, and Y203 powder were each manufactured by Rare Metallic Co., Ltd. and had a purity of 99.99%.

[First calcination step] B: Add 10% of Y20s powder as a stabilizer to t203 powder.
Add mo (5%) and add this to Hirobolibin (250ml)
The mixture was mixed for 50 minutes. Thereafter, wet mixing was carried out for 30 minutes in an alumina mortar (special grade C2H50H was used, C2H50H was also used for subsequent wet mixing and pulverization), and the mixture was dried with an infrared lamp.

Put the finished mixed powder into a platinum crucible and heat it 1'1.
The product was fired at 800° C. for 5 hours in a Matsufuru furnace in an irritant atmosphere, and then rapidly cooled at room temperature. This fired product PX-ray powder -
When identified by the Chard method, it was found that the δ phase was not complete, but a slight amount of β phase was mixed in. The above baked product was wet-ground in a mortar (30 minutes), and then crushed again in a Matsufuru furnace at 850°C for 5 hours. (inair) and quenched at room temperature. When this fired product was identified by the X-ray powder-chard method, it was found to be completely δ-Bt,Q. Furthermore, when this δ-Bi2's4° was subjected to thermal measurement (TG) and differential thermal analysis (DTA), it was found that the phase was stable up to 930°C.

[Second calcination step] Add 10 mo of Y2O3 powder to ZrO7 powder as a stabilizer.
1% was added, and wet mixing (6 hours) was performed using a ball mill. The container at this time is 8.5 cv lX11
．． An O- plastic container was used, and all balls were zirconia balls manufactured by Nippon Kagaku Toki. The mixture was transferred to a beaker, the alcohol was evaporated moderately on a hot plate (90'C), and then dried with an infrared lamp. This dry mixture was placed in a platinum crucible and heated in a Kanthal super furnace for 1
500"Cs 5 hours ('in air) firing and furnace cooling. When this fired product was identified by the X-ray powder-chard method, it was found to be a complete CQ b 1c Zr.
(') It was 2.

[Powder mixing process]

The above δ-Bi203 and ('ubic Z r 0
2 in an alumina mortar (for 30 minutes),
Put them through a 200 me-suke sieve.
The material of h or more was used as the material for the next main firing. After sufficiently drying these materials, 86 ma1% of δ-Bi203
, Cubic zro2 was mixed at 14+r+o (9%) and wet mixed (15 minutes) using an agate mortar.
n, /6. Formed into a rectangular parallelepiped of 5 x 15 x 5 mm at a pressure of RL, placed on a platinum plate in a Matsufuru furnace, and heated at 930°C.
The product was fired for 2 hours and cooled in a furnace to obtain the desired solid electrolyte. When this was identified by the X-ray powder-chard method, it was confirmed that a solid solution of δ-Bi203 and Cubic ZrO2 was formed.

FJ La1h solid electrolyte, ((Bi2O3) (1
q (Y20s) 0.1) 0.86C (Zr02)
The electrical conductivity of 0.9 (Y2O3) (11) 0.14 was determined at 500°C to 700°C along with the following comparative example.

・Comparative example 1. -- (Bi203) 0.9 (Y20
s ) (11・Comparative example 2 -- ((Bi2O3) 0
．． 9 (Y20s). 4) 0.5((ZrO2)
B9(Y2O3) o, 1) (15・Comparative example 3...
...((B 1203).9(Y2O3).1).,
2((zro2)0.9' Y2O3)0.1) (
3,6 Comparative example 4 --- (Zr02) 0,9 (Y
2O3) o, i The above examples are 5 x 15 x 5 at a pressure of 1.31 C/cr&, similar to the product of the present invention.
It was molded into an im rectangular parallelepiped.

These products of the present invention and each comparative example were coated with #400 emery paper.
The surface was polished using #1500 and platinum was sputtered on both ends, and this was used as an electrode. Sandwich this between platinum plates,
l:mpedanceAnalgze from 600°C to 700°C with increasing temperature in a gold furnace.
r(Yl(R4192A, LF) for frequency dependence of impedance from 10MHz to 1011z
It was measured in the range up to In this measurement, once the predetermined temperature became constant, annealing was performed for 1 hour, and then the next measurement was performed. The temperature dependence of the electrical conductivity of each sample obtained through this impedance measurement was investigated. The graph in FIG. 1 shows the results.

As can be seen from this graph, the product of the present invention has a conductivity that is more than two orders of magnitude higher than that of the single Cubic-Z rQ2 (Comparative Example 4).
Compared to (Comparative Example 1), the conductivity is approximately the same in the high temperature range of 550°C or higher, but is about 3 to 4 times higher in the low temperature range of about 550°C or lower. In addition, mixed sintered bodies mixed and fired at other molar ratios (Comparative Example 2.3
) shows an average conductivity that is about one order of magnitude higher than that of

In addition, separately from the above measurement, ((Bi20.).q (Y
20g). , 1X ((Zr02) ., q (Yt
Os). , 1) In the composition 1-x, X is 1. O
A sintered body with a diameter of 0.0 to 0.86 was prepared, and its lattice constant was determined by the X-ray powder-chard method using silicon (manufactured by Rare Metallic Co., Ltd., purity 9999%) as an internal standard.
As shown in the figure, it was found that as the solid solution amount of Cubic-Z r 02 increased, the lattice constant increased and reached a maximum value at about x=0.86.

However, when X is 0.86 or less, it is almost constant. and,
When we measured their electrical conductivity at the same time, we found that as the lattice constant increased, the electrical conductivity also increased, and similarly reached approximately x = 0.
．． It was confirmed that the maximum value was shown at 86. Also, X is 0.
86 or more, it is a single phase region and δ-Bi203 and cubic crystal-
It was found that ZrO was completely dissolved in solid solution.

Therefore, the product of the present invention is different from the conventional δ-B i20. and Cu
Cubic Zr dissolved in δ-B 120s has a higher conductivity than each individual bic Zr0z.
The reason for this is thought to be that O2 increases the phase lattice length and facilitates the movement of oxygen ions.

In addition, when the structure dependence of the ten-grain boundary resistance at each temperature is determined, it is shown in Figure 3. At a low temperature of -550°C or less and when
i20. ] [1,9(Y2O2) (The electrical conductivity was superior to that of 11 alone.)

On the other hand, regarding the coefficient of thermal expansion, a rectangular parallelepiped sample ζF was prepared by polishing with #400 to #1500 emery paper from the above-mentioned product of the present invention, and Delight Make 16 manufactured by Shinku Riko Co., Ltd.
00 was used, both ends were pressed with appropriate pressure, and the expansion and contraction with respect to changes in lewdness was determined using a differential transformer.

As a result, the volume change at around 960°C was as follows: -0.17% physique expansion occurred during the heating process, and -0.10% volume contraction during the cooling process.

On the other hand, the volume change due to the polymorphic transition of [purθ]2o3 is +6.9% for (α'th → δ phase), -21% for (δ phase → β phase), and -21% for (δ phase → γ phase). ) was reported to be -45%, and these changes revealed that the volume change of the above-mentioned product of the present invention was smaller by one order of magnitude or more. In the product of the present invention, kneading is the δ phase, Cubi
Since no other structures other than the c-structure were observed, the pixel pores in the system were not regularized at low temperatures, but became disordered at high temperatures, indicating that a so-called regular-disorder transition occurred. I don't think this is due to the presence of

From the above results, it is clear that the solid electrolyte according to the present invention has more practical value than conventional single solid electrolytes. In addition, in this embodiment O, ZrO2, B1□0
．． Although Y20s was used as the stabilizer, it goes without saying that other known stabilizers may be used instead.

Furthermore, although a solid line example is shown for a stabilizer composition ratio of 10 moe%, excellent effects can be obtained if the composition ratio is within the range of about 5 to 3 Dmo1%.

As explained above, the present invention involves mixing powdered bismuth oxide with about 5 to 30 mo1% of a powdered stabilizer, kneading, and baking the mixture to form stabilized bismuth oxide. process, powdered zirconium oxide, about 5 to 3 o
A second calcination step in which stabilized bismuth oxide and stabilized zirconium oxide are mixed and calcined to form stabilized zirconium oxide. Make it into a powder and mix it at a mixing ratio of about 60 mo1%.
The stabilized bismuth oxide and the mixing ratio of about 40
This method consists of a powder mixing step in which stabilized zirconium oxide is mixed with a mo of 1% or less, and a main firing step in which this powder mixture is molded and fired.Since the solid electrolyte obtained by this method has a low conductivity. It can be used to soften solid electrolytes that have a high coefficient of thermal expansion and a small coefficient of thermal expansion, and has great practical utility in fields such as acid mesosensors and fuel cells.

[Brief explanation of the drawing]

Fig. 1 is a graph plotting the conductivity of the solid electrolyte according to the present invention and the solid electrolyte of the comparative example with respect to humidity dependence, and the 21st graph is a graph plotting the conductivity of the solid electrolyte according to the present invention and the solid electrolyte of the comparative example.
FIG. 3 is a graph plotting changes in lattice constant due to changes in composition with zr02, and FIG. 3 is a graph showing the dependence of ten-grain boundary resistance on structure. Applicant Lefkura Electric Cable Co., Ltd. Procedural Amendment (Voluntary) Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent Koma 1 No. 56224 2, Name of the invention Solid electrolyte and its unique manufacturing method 3, Make amendments. person waiting for the meeting νtlj person (stg) Fujisuke't4ε line ijushikikai 7J: (haga 1
Name) 4, Agent Akira, dll-do's 1st hand Ml'i > 1 <range'', 1
-I'lmi of the invention, +41tl explanation J, I-illustration r
Each episode of ``Side n simple explanation''. (1) Correct the ``Separate set:'' in the first paragraph of ``Special B'F 1tri search range υ, 11'' of Aiill WV. 12) On page 6, line 11, “airJ Toa 6 no Thr’
7 Ki” and KJ’correct”f/-)〇(3) 6th fi/7~/g line, 7th Fj/1l-
(When it says "1nairJ" on the j'th line, I
T Correct 〇 (4) 7th Tei line 16, @lza line 9, page g, line 3, Dosei lO line, page 9/q 100th street, io
Tei line 12, t'gi line 3, same page line q, 7th
．． 2 m:l 1st line, 1st page ψ line, ``
The text that says “eu bi cl” has been corrected to “UV square crystal”.
do. (5) Row 1 with "Get 11 examples of the above fruits, each with the product of the present invention", all "Compare the above f!lI
U G2, respectively 1&+1 examples of the above-mentioned products of the present invention and 9 negative 1.1-ro. (6) On page 9, line 5, ``these products of the present invention, tq, and each comparative example'' has been replaced with ``these comparative examples and the solid ``black matter'' which is the above-mentioned example of the present invention''. I am corrected. (7) rl+npe in the q y q to to rows,
dance AnalgzerJ and a certain "impedance analyzer" and JIF. (8) "xfOJ"-too~C on the tomg-9th line
, 86 sintered body 2 was created" was deleted. (9) Does it say "structure dependence of grain boundary resistance of ten grains" in sections 7 to 5]'? Corrected to "composition dependence of grain bulk + grain interface resistance." 0(1 analysis s t t Bl t tt, ~t3rd line is “
Is there a Delight Meter J? Correct it as "delight meter"〇(１υ 對'S/Page 2, correct it as "pure")
Does it say 'wa'? “Pure” stops me. (I21 In the 5th and 6th lines of the first
"Composition dependence of ai resistance" and i4J' jE jro. Claims il+ Stabilized bismuth and stabilized 11'
Consisting of zirconium 9ide and stabilized in 1111 [1(
A solid 71 chloride characterized by containing about 60 mo 73% or more of bismuth chloride. (2) Powdered 7' stabilizer with 1% O for about 5~30 to powdered hismuth hexanide? Mix this with stabilized t′-added bismuth? Approximately 5 to 30 mo7 is formed on the first hair culm and the λ3r powdered hexazo zirconium.
% of the powdered stabilizer is combined and fired to form stabilized zirconium oxide.
The above-mentioned stabilized bismuth silicide and stabilized zirconium nitride were powdered and mixed for about 60 minutes.
A powder mixture of 1 cup of stabilized bismuth with a concentration of 1% pJ or above and a stabilized zirconium nitride with a concentration of about 401 mm was added, and this powder mixture was completely molded and made by itself. Book to be fired! ε Sei

Claims (2)

[Claims] (1) A solid electrolyte comprising stabilized bismuth oxide and stabilized zyl-lam oxide, and containing about 60 moe% or more of the stabilized bismuth oxide. (2) A first calcination step in which about 5 to 6 degrees of powdered stabilizer is mixed with powdered bismuth oxide and the mixture is fired to form stabilized bismuth oxide; Mix about 5-30 ma1% of powdered stabilizer,
The second step is to sinter this to form stabilized zirconium oxide.
The above-mentioned stabilized bismuth oxide and stabilized zirconium oxide are powdered, and the mixing ratio is about 60 mo.
A powder mixing step of mixing stabilized bismuth oxide with a mixing ratio of 1% or more and stabilized zirconium oxide with a mixing ratio of about 40 mo1% or less, and a main firing step of molding this powder mixture and firing it. A method for producing a solid electrolyte.