JPH113720A - Inter-connector material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inter-connector material for solid electrolyte type electrochemical cell. SOLUTION: Y2 O3 -stabilized ZrO2 , made of lanthanum chromite material and expressed by formulas (La1-x Srx ) (Cr1-y-z Tiy Coz )O3 (where 0.1<=x<=0.2, 0.01<=y<=0.1, 0.01<=z<=0.05), (La1-x 'Srx ') (Cr1-y '-z 'Tiy 'Niz ')O3 (where 0.1<=x'<=0.2, 0.01<=y'<=0.05, 0.01<=z'<=0.08) or (La1-x" Srx" ) (Cr1-y"-z" Tiy" Fez" )O3 (where 0.1<=x"<=0.2, 0.01<=y"<=0.05, 0.01<=z"<=0.05) is used as solid electrolyte. That is, Sr is substituted for one part of La of lanthanum chromite (LaCrO3 ), and furthermore Ti and Co, Ti and Ni, or Ti and Fe are substituted for one part of Cr so that expansion in a high-temperature reducing atmosphere can be prevented, and conductivity and a coefficient of thermal expansion can be maintained at high values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lanthanum chromite material which can be advantageously used as an interconnect material for an electrochemical cell such as a solid oxide fuel cell or a solid oxide steam electrolyzer.

[0002]

2. Description of the Related Art For example, a solid oxide fuel cell (hereinafter, referred to as a solid oxide fuel cell)
In the case of an SOFC, an interconnector is used as a connection material in order to obtain electric power by increasing the voltage by forming a single cell into multiple layers. The interconnector makes electrical connection and at the same time high temperature, oxidizing gas (air)
It also has the role of separating the reducing gas (fuel). Accordingly, lanthanum chromite doped with a perovskite-type oxide such as Mg, Ca, or Sr is used as an interconnector material as a metal and a metal having a high melting point as an oxide.

[0003]

SUMMARY OF THE INVENTION Even with high melting point metals, SO
Since the use temperature of FC is as high as about 1000 ° C., even when used for a long time, an oxide is formed in an oxidizing atmosphere, and the surface becomes an insulator, which is not preferable because electric conduction is deteriorated. On the other hand, lanthanum chromite, which is an oxide, is stable in an oxidizing atmosphere, but has low conductivity, and has a problem that it is reduced in a reducing atmosphere and its properties such as conductivity are easily changed. Therefore, to improve conductivity, Mg, C
It is used by doping an alkaline earth metal such as a or Sr. The conductivity of lanthanum chromite doped with Sr>Ca> Mg increases in the order of Sr>Ca> Mg.

[0004] Next, SOFC is a solid electrolyte (YSZ: Y
_Since it is a composite of ₂ O ₃ -stabilized ZrO ₂ ), an electrode such as an oxygen electrode and a fuel electrode, and an interconnector, the thermal expansion coefficient of the interconnector and the base YSZ must be the same. From this point, the lanthanum chromite doped with Sr has a thermal expansion coefficient of about 10 × 10 ⁻⁶ ° C. ^−1, which is almost the same as YSZ which is a solid electrolyte. Therefore, lanthanum chromite doped with Sr, which has a high conductivity and a thermal expansion coefficient substantially equal to that of YSZ which is a solid electrolyte, is used as an interconnector for SOFC.

However, looking at the behavior in a reducing atmosphere, it is presumed that Sr-doped lanthanum chromite has a relatively large expansion due to reduction, which causes deformation and cracking of the interconnector and peeling of electrodes.

The present invention has been made in view of the state of the art, and has a low reduction expansion coefficient, a high conductivity, and a lanthanum chromite material whose thermal expansion coefficient is close to the thermal expansion coefficient of YSZ of 10.2 × 10 ^-6 ° C ^-1. It is intended to provide an interconnector material comprising the same.

[0007]

The present invention provides (1) (La)
_1-x Sr _x ) (Cr _1-yz Ti _y Co _z ) O ₃ (However,
0.1 ≦ x ≦ 0.2,0.01 ≦ y ≦ 0.1,0.01
≦ z ≦ 0.05) An interconnector material for an electrochemical cell using Y ₂ O ₃ -stabilized ZrO ₂ as a solid electrolyte, characterized by comprising a lanthanum chromite material represented by the general formula: _{1-x '} Sr _x' ) (Cr _{1-y'-z '}
Ti _{y ′} Ni _{z ′} ) O ₃ (provided that 0.1 ≦ x ′ ≦ 0.2,
0.01 ≦ y ′ ≦ 0.05, 0.01 ≦ z ′ ≦ 0.0
Characterized by comprising from lanthanum chromite material represented by 8) becomes formula Y ₂ O ₃ interconnector material of the electrochemical cell to stabilize ZrO ₂ solid electrolyte and (3) (La 1-x "Sr _{x "} ) (Cr _{1-y" -z "} Ti _y" Fe
_{z "} ) O ₃ (However, 0.1≤x" ≤0.2, 0.01≤
wherein Y ₂ O ₃ -stabilized ZrO ₂ is a solid electrolyte comprising a lanthanum chromite material represented by a general formula: y ″ ≦ 0.05, 0.01 ≦ z ″ ≦ 0.05) Cell interconnector material.

That is, the present invention uses strontium (Sr) as a doping element for lanthanum chromite, and further uses titanium (Ti) and cobalt (Co), titanium (Ti) and nickel (Ni), or titanium (Ti) and iron By adding (Fe), the conductivity is high and the thermal expansion coefficient is about 10 × 10 ⁻⁶ ° C. ^−1, which is relatively large as ceramics, and the expansion accompanying the release of oxygen is zero even under a high-temperature reducing atmosphere. A very small material of about 1% or less has been developed.

(Function) In the present invention, while maintaining the thermal expansion coefficient of lanthanum chromite material at about the same level as that of YSZ, the lanthanum chromite material is used to prevent expansion during reduction without substantially reducing conductivity. The addition of Ti and Co, Ti and Ni, or Ti and Fe to stabilize the trivalent Cr to the element obtained by substituting Sr as a solid solution element of La suppresses expansion during reduction. It is made possible.

For example, when 15% of La in lanthanum chromite represented by LaCrO ₃ is replaced by Sr, 10%
The conductivity at 00 ° C. is as high as 30 S · cm ^−1, and
The coefficient of thermal expansion is also approximately 10 × 10 ⁻⁶ ° C. ⁻¹ , which is almost the same as YSZ, which is a main component of the SOFC. By substituting a part of Cr with Ti and Co, Ti and Ni or Ti and Fe, the property required as an interconnector of the SOFC, that is, the thermal expansion coefficient is Y.
SZ is made to substantially match SZ, the conductivity is high, and expansion during reduction can be almost prevented.

The interconnect material of the present invention is (La
_1-xSr_x) (Cr_1-yzTi_yCo _z) O_Three(However,
0.1 ≦ x ≦ 0.2,0.01 ≦ y ≦ 0.1,0.01
≦ z ≦ 0.05) or (La_{1-x '}Sr_{x '}) (Cr
_{1-y'-z '}Ti_{y '}Ni_{z '}) O_Three(However, 0.1 ≦ x ′ ≦
0.2, 0.01 ≦ y ′ ≦ 0.05, 0.01 ≦ z ′ ≦
0.08) or (La_{1-x "}Sr_{x "}) (Cr_{1-y "-z"}T
i_{y "}Fe_{z "}) O_Three(However, 0.1 ≦ x ″ ≦ 0.2, 0.
01 ≦ y ″ ≦ 0.05, 0.01 ≦ z ″ ≦ 0.05)
X, y, z values,
The x ', y', z 'values or x ", y", z "values are
Bending of interconnector when tension coefficient is 0.13% or less
Within the allowable limit of cracking and cracking, conductivity of 10 S · c
m^-1As described above, there is no practical problem with the interconnector
And a coefficient of thermal expansion of 9.9 to 10.5 × 10^-6
° C^-1To be close to the thermal expansion coefficient of YSZ
It is set.

[0012]

EXAMPLES The effects of the present invention will be clarified by giving specific examples of the present invention.

(Example 1) An oxide having the following composition, (La _1-x S
r _x ) (Cr _1-yz Ti _y Co _z ) O ₃ (where 0 ≦ x
≦ 0.5, 0 ≦ y ≦ 0.2, 0 ≦ z ≦ 0.2).

As raw material powders, lanthanum oxide, strontium carbonate, chromium oxide, titanium oxide and cobalt oxide are blended in a predetermined ratio, and then mixed using a ball mill.
Next, heat treatment was performed at 1300 ° C. for 10 hours to obtain a composite oxide powder. Next, a uniaxial press at 100 kg / cm ² was performed to obtain a disc of about 60 mmφ × 5 mmt.
A molded article was obtained by CIP treatment at 0 kg / cm ² . next,
Sintering was performed under each condition of 1500 to 1700 ° C. to obtain a sintered body. Next, a test piece of 3 × 4 × 40 mm was processed from the disc sintered body to obtain a sample for measuring physical properties. Each physical property measurement was performed as follows.

[Reduction expansion coefficient] The test piece was kept in a hydrogen atmosphere at 1000 ° C for 5 hours, cooled, and the change in length was measured.

[Electrical Conductivity] Four platinum lead wires (interval: about 10 mm) were wound around a test piece, and measured at each temperature by a DC four-terminal method.

[Coefficient of thermal expansion] A test piece was heated at 10 ° C / m
The temperature was raised in, and the thermal expansion was continuously measured.

FIG. 1 shows the data of the reduction expansion coefficient. The horizontal axis shows the y value of the above general formula, and the vertical axis shows the reduction expansion coefficient (%). However, in this case, the value of x in the above general formula is 0.2, and the value of z is
The value was fixed at 0. When y = 0, the reduction expansion coefficient is 0.
While the value is as large as 3%, even if x = 0.2, if the y value is larger than 0, the reduction expansion coefficient decreases.

FIG. 2 shows the conductivity at 1000 ° C.
The horizontal axis represents the y value of the general formula, and the vertical axis represents the conductivity (S · c).
m ^-1 ). Also in this case, the value x in the above general formula is 0.2.
And the z value was fixed at 0. If y = 0, the conductivity is 37
Although it is as high as S · cm ⁻¹ , the conductivity decreases when the y value is larger than 0.

FIG. 3 shows the coefficient of thermal expansion. The horizontal axis is the above general
The vertical axis represents the y value of the equation, and the vertical axis represents the coefficient of thermal expansion (× 10^-6° C^-1)
You. Also in this case, the x value of the above general formula is 0.2, and the z value is 0.
Fixed to. When y = 0, the coefficient of thermal expansion is 10.3 × 1
0^-6° C^-1And YSZ (10.3 × 10 ^-6° C^-1) And almost match
However, the coefficient of thermal expansion decreases as the y value increases.
You.

As a result, it has been found that, by increasing the y value, that is, by increasing the amount of replacing Cr with Ti, the reduction expansion coefficient decreases, the conductivity decreases, and the thermal expansion coefficient decreases. did.

FIG. 4 shows the data of the reduction expansion coefficient. The horizontal axis represents the x value of the above general formula, and the vertical axis represents the reduction expansion coefficient (%). However, in this case, the y value of the general formula is set to 0.1, and z
The value was fixed at 0. When y = 0.1, the reduction expansion coefficient increases as the x value increases.

FIG. 5 shows the conductivity at 1000 ° C.
The horizontal axis is the x value of the above general formula, and the vertical axis is the conductivity (S · cm ⁻¹ ).
It is. Also in this case, the y value of the general formula was fixed at 0.1, and the z value was fixed at 0. When x = 0, the conductivity is 1 S · cm ⁻¹
But the conductivity increases as the x value increases.

FIG. 6 shows the coefficient of thermal expansion. The horizontal axis indicates the x value of the above general formula, and the vertical axis indicates the coefficient of thermal expansion (× 10 ⁻⁶ ° C. ⁻¹ ).
Also in this case, the y value of the general formula was fixed at 0.1, and the z value was fixed at 0. When x = 0, the coefficient of thermal expansion is 7.5 × 10 ⁻⁶ ° C.
It has a much lower value than the ^-1 and ^{YSZ (10.3 × 10 -6 ℃ -1} ) , but the thermal expansion coefficient with increasing x values is larger.

As a result, the x value increases, that is, La
It has been found that increasing the amount of Sr substituted with Sr increases the reduction expansion coefficient, but also increases the conductivity and the thermal expansion coefficient.

FIG. 7 shows an x value of 0.15 and a y value of 0.03.
(The reason why the x and y values are fixed in this way is that it has been found from the analysis so far that relatively good characteristics can be obtained).
The horizontal axis indicates the z value of the above general formula, and the vertical axis indicates the reduction expansion coefficient (%). It has been found that when the value of z is increased, the reduction expansion coefficient is increased.

FIG. 8 shows an x value of 0.15 and a y value of 0.03.
Shows the data of the electrical conductivity when fixed. The horizontal axis represents the z value of the general formula, and the vertical axis represents the conductivity (S · cm ⁻¹ ). It has been found that increasing the z value decreases the conductivity.

FIG. 9 shows an x value of 0.15 and a y value of 0.03.
Shows the data of the coefficient of thermal expansion when fixed to. The horizontal axis is z
The vertical axis indicates the coefficient of thermal expansion. It can be seen that the thermal expansion coefficient increases as the z value increases.

When applied as an interconnector material such as SOFC, it is necessary that the interconnector material has a high thermal conductivity at the same time as the thermal expansion coefficient of YSZ, which is a solid electrolyte, and has a low reduction expansion coefficient. However, as a result of the above analysis, the general formula (La _1-x Sr _x )
The (x, y, z) values of (Cr _{1 -yz} Ti _y Co _z ) O ₃ are
0.1 ≦ x ≦ 0.2,0.01 ≦ y ≦ 0.1,0.01
.Ltoreq.z.ltoreq.0.05, and particularly preferred ranges are 0.13.ltoreq.x.ltoreq.0.17, 0.02y.ltoreq.0.04.
0.02 ≦ z ≦ 0.04, where x = 0.1
5, y = 0.03, z = 0.03 is most preferred.

(Example 2) An oxide having the following composition, (La _{1-x ′} S)
r _{x ′} ) (Cr _{1−y′−z ′} Ti _{y ′} Ni _{z ′} ) O ₃ (where 0 ≦
x'≤0.5, 0≤y'≤0.2, 0≤z'≤0.2)
Was prototyped.

As raw material powders, lanthanum oxide, strontium carbonate, chromium oxide, titanium oxide, and nickel oxide are blended in a predetermined ratio, and then mixed using a ball mill.
Next, heat treatment was performed at 1300 ° C. for 10 hours to obtain a composite oxide powder. Next, a uniaxial press at 100 kg / cm ² was performed to obtain a disc of about 60 mmφ × 5 mmt.
A molded article was obtained by CIP treatment at 0 kg / cm ² . next,
Sintering was performed under each condition of 1500 to 1700 ° C. to obtain a sintered body. Next, a test piece of 3 × 4 × 40 mm was processed from the disc sintered body to obtain a sample for measuring physical properties. The measurement of each physical property, that is, the reduction expansion coefficient, the conductivity, and the thermal expansion coefficient was performed by the method shown in Example 1.

FIG. 10 shows the data of the reduction expansion coefficient. The horizontal axis represents the y 'value of the above general formula, and the vertical axis represents the reduction expansion coefficient (%).
Is shown. However, in this case, the value x 'of the general formula is 0.2
And the z 'value was fixed at 0. When y '= 0, the reduction expansion coefficient is as large as 0.3%, but when x' = 0.2, if the y 'value is larger than 0, the reduction expansion coefficient becomes smaller.

FIG. 11 shows the conductivity at 1000 ° C. The horizontal axis represents the y 'value of the general formula, and the vertical axis represents the conductivity (S ·
cm ^-1 ). Also in this case, the value of x 'in the general formula is 0.
At 2, the z 'value was fixed at 0. When y ′ = 0, the conductivity is as high as 37 S · cm ⁻¹ , but when the y ′ value is larger than 0, the conductivity decreases.

FIG. 12 shows the coefficient of thermal expansion. The horizontal axis represents the y 'value of the above general formula, and the vertical axis represents the coefficient of thermal expansion (× 10 ⁻⁶ ° C. ⁻¹ ). Also in this case, the value of x 'in the above general formula is 0.2, and the value of z' is
The value was fixed at 0. When y '= 0, the coefficient of thermal expansion is 1
0.3 × 10 ^-6 ℃ ^-1 and YSZ (10.3 × 10 ^-6 ℃ ^-1 )
However, the coefficient of thermal expansion decreases as the y 'value increases.

As a result, the increase of the y 'value, that is,
It has been found that, by increasing the amount of substitution of Ti with Ti, the reduction expansion coefficient decreases, the conductivity decreases, and the thermal expansion coefficient also decreases.

FIG. 13 shows the data of the reduction expansion coefficient. The horizontal axis indicates the x 'value of the above general formula, and the vertical axis indicates the reduction expansion coefficient (%). However, in this case, the y 'value of the general formula is 0.1
And the z 'value was fixed at 0. If y '= 0.1, x'
As the value increases, the reduction expansion coefficient increases.

FIG. 14 shows the conductivity at 1000 ° C. The horizontal axis is the x ′ value of the above general formula, and the vertical axis is the conductivity (S · c).
m ^-1 ). Also in this case, the value of y 'in the above general formula is set to 0.1.
And the z 'value was fixed at 0. When x ′ = 0, the conductivity is as low as ¹ S · cm ⁻¹ , but the conductivity increases as the x ′ value increases.

FIG. 15 shows the coefficient of thermal expansion. The horizontal axis is
The x 'value of the general formula, and the vertical axis represents the coefficient of thermal expansion (× 10^-6° C^-1)
You. Also in this case, the value of y 'in the above general formula is set to 0.1, and the value of z' is
Was fixed to 0. When x '= 0, the coefficient of thermal expansion is 7.5
× 10^-6° C^-1And YSZ (10.3 × 10 ^-6° C^-1)compared to
Is very low, but as x 'increases,
The coefficient of thermal expansion is large.

As a result, the increase in the value x ', that is, L
It has been found that by increasing the amount of replacing a with Sr, the reduction expansion coefficient increases, but the conductivity and the thermal expansion coefficient also increase.

FIG. 16 shows that the x 'value is fixed at 0.15 and the y' value is fixed at 0.03. Is obtained.) Is shown. The horizontal axis is the z 'value, and the vertical axis is the reduction expansion coefficient (%).
Is shown. As a result, it was found that when the value of z 'was increased, the reduction expansion coefficient was increased.

FIG. 17 shows conductivity data when the x 'value is fixed at 0.15 and the y' value is fixed at 0.03. The horizontal axis indicates the z 'value, and the vertical axis indicates the conductivity. It has been found that the conductivity decreases as the z 'value increases.

FIG. 18 shows the data of the coefficient of thermal expansion when the x 'value is fixed at 0.15 and the y' value is fixed at 0.03.
The horizontal axis indicates the z ′ value, and the vertical axis indicates the coefficient of thermal expansion. It was found that as the z 'value was increased, the coefficient of thermal expansion was increased.

When applied as an interconnector material for SOFCs and the like, it is necessary that the thermal expansion coefficient be substantially the same as that of YSZ, which is a solid electrolyte, and at the same time, the conductivity be high and the reduction expansion coefficient be small. (La _{1-x '} S
_{r x ') (Cr 1-} y'-z' Ti y 'Ni z') O 3 of x ',
The values of y ′ and z ′ are 0.1 ≦ x ′ ≦ 0.2, 0.01 ≦
It is preferable that y ′ ≦ 0.05 and 0.01 ≦ z ′ ≦ 0.08, among which x ′ = 0.15, y ′ = 0.03, z ′
= 0.05 is most preferred.

(Example 3) An oxide having the following composition, (La _{1-x "} S
_{r x ") (Cr 1-} y" -z "Ti y" Fe z ") O 3 ( where, 0 ≦
x "≤0.5, 0≤y" ≤0.4, 0≤z "≤0.2)
Was prototyped.

As raw material powders, lanthanum oxide, strontium carbonate, chromium oxide, titanium oxide and iron oxide are blended in a predetermined ratio, and then mixed using a ball mill.
Heat treatment was performed at 300 ° C. for 10 hours to obtain a composite oxide powder. Next, press uniaxially at 100 kg / cm ² to
After obtaining a disc of about 0mmφ × 5mmt, 2000kg
/ Cm ² to obtain a molded article. Next, 150
Sintering was performed under each condition of 0 to 1700 ° C. to obtain a sintered body. Next, a test piece of 3 × 4 × 40 mm was processed from the disc sintered body to obtain a sample for measuring physical properties. The measurement of each physical property, that is, the reduction expansion coefficient, the conductivity, and the thermal expansion coefficient was performed by the method shown in Example 1.

FIG. 19 shows reduction expansion coefficient data. The horizontal axis represents the y ″ value of the above general formula, and the vertical axis represents the reduction expansion coefficient (%).
Is shown. However, in this case, the x ″ value of the general formula is 0.2
In addition, the z ″ value is fixed to 0. When y ″ = 0, the reduction expansion coefficient is as large as 0.3%, but when the y ″ value is larger than 0 even at x ″ = 0.2, the reduction expansion coefficient is Becomes smaller.

FIG. 20 shows the conductivity at 1000 ° C. The horizontal axis represents the y ″ value of the general formula, and the vertical axis represents the conductivity (S ·
cm ^-1 ). Also in this case, the value of x ″ in the general formula is 0.
2, the z ″ value is fixed at 0. When y ″ = 0, the conductivity is as high as 37 S · cm ⁻¹ , but when the y ″ value is larger than 0, the conductivity decreases.

FIG. 21 shows the coefficient of thermal expansion. The horizontal axis represents the y ″ value of the above general formula, and the vertical axis represents the coefficient of thermal expansion (× 10 ⁻⁶ ° C. ⁻¹ ).
The value was fixed at 0. When y ″ = 0, the coefficient of thermal expansion is 1
0.3 × 10 ^-6 ℃ ^-1 and YSZ (10.3 × 10 ^-6 ℃ ^-1 )
However, the coefficient of thermal expansion decreases as the y ″ value increases.

As a result, the increase of the y ″ value, that is, Cr
It has been found that, by increasing the amount of substitution of Ti with Ti, the reduction expansion coefficient decreases, the conductivity decreases, and the thermal expansion coefficient also decreases.

FIG. 22 shows the data of the reduction expansion coefficient. The horizontal axis represents the x ″ value of the general formula, and the vertical axis represents the reduction expansion coefficient (%). In this case, the y ″ value of the general formula is 0.1.
In addition, the value of z ″ is fixed to 0. When y ″ = 0.1, x ″
As the value increases, the reduction expansion coefficient increases.

FIG. 23 shows the conductivity at 1000 ° C. The horizontal axis is the x ″ value of the general formula, and the vertical axis is the conductivity (S · c).
m ^-1 ). Also in this case, the value of y ″ in the above general formula is 0.1.
In addition, the z ″ value is fixed to 0. When x ″ = 0, the conductivity is as low as ¹ S · cm ⁻¹ , but the conductivity increases as the x ″ value increases.

FIG. 24 shows the coefficient of thermal expansion. The horizontal axis is
The x ″ value of the general formula, and the vertical axis represents the coefficient of thermal expansion (× 10^-6° C^-1)
You. Also in this case, the y ″ value of the above general formula is set to 0.1, and the z ″ value is
Was fixed to 0. When x ″ = 0, the coefficient of thermal expansion is 7.5
× 10^-6° C^-1And YSZ (10.3 × 10 ^-6° C^-1)compared to
Is very low, but as the x ″ value increases,
The coefficient of thermal expansion is large.

As a result, an increase in the value of x ″, ie, L
It has been found that by increasing the amount of replacing a with Sr, the reduction expansion coefficient increases, but the conductivity and the thermal expansion coefficient also increase.

FIG. 25 shows that the x ″ value is fixed at 0.15 and the y ″ value is fixed at 0.03 (the fixed x ″ and y ″ values are relatively good from the analysis so far). This is because it was found that a result was obtained). The horizontal axis indicates the z ″ value, and the vertical axis indicates the reduction expansion coefficient (%). As a result, it was found that the reduction expansion coefficient increases as the z ″ value increases.

FIG. 26 shows conductivity data when the x ″ value is fixed at 0.15 and the y ″ value is fixed at 0.03. The horizontal axis represents the z ″ value and the vertical axis represents the conductivity. It has been found that increasing the z ″ value decreases the conductivity.

FIG. 27 shows the data of the coefficient of thermal expansion when the x ″ value is fixed at 0.15 and the y ″ value is fixed at 0.03.
The horizontal axis represents the z ″ value, and the vertical axis represents the coefficient of thermal expansion. It was found that increasing the value of z ″ increases the coefficient of thermal expansion.

When applied as an interconnector material for SOFCs and the like, it is necessary that the thermal expansion coefficient be substantially the same as that of the solid electrolyte YSZ, and at the same time, the conductivity be high and the reduction expansion coefficient be small. (La _{1-x "} S
_{r x ") (Cr 1-} y" -z "Ti y" Fe z ") O 3 for x",
The values of y ″ and z ″ are 0.1 ≦ x ″ ≦ 0.2 and 0.01 ≦
Preferably, y ″ ≦ 0.05, 0.01 ≦ z ″ ≦ 0.05, of which x ″ = 0.15, y ″ = 0.03, z ″
= 0.05 is most preferred.

[0058]

According to the present invention, lanthanum chromite (L
a part of La of aCrO ₃ ) is replaced with Sr,
Is a lanthanum chromite interconnect material that can prevent expansion under a high-temperature reducing atmosphere and maintain a high conductivity and a high thermal expansion coefficient by replacing a part of Ti with Co, Ti and Ni or Ti and Fe. Can be provided.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing (La _1-x Sr _x ) (Cr _1-yz Ti
₆ is a chart showing the variation of the reduction expansion coefficient when y is varied, where x = 0.2 and z = 0 of _y Co _z ) O ₃ .

FIG. 2 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
₆ is a chart showing a change in conductivity when y is changed, where x = 0.2 and z = 0 of _y Co _z ) O ₃ .

FIG. 3 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
₇ is a chart showing the variation of the coefficient of thermal expansion when y is varied, where x = 0.2 and z = 0 of _y Co _z ) O ₃ .

FIG. 4 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
₆ is a chart showing a change in the reduction expansion coefficient when y is set to y = 0.1 and z = 0 in _y Co _z ) O ₃ and x is changed.

FIG. 5 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
₆ is a table showing a change in conductivity when y is set to y = 0.1 and z = 0 of _y Co _z ) O ₃ and x is changed.

FIG. 6 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
₆ is a chart showing a change in a coefficient of thermal expansion when y is set to y = 0.1 and z = 0 of _y Co _z ) O ₃ and x is changed.

FIG. 7 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
_y Co _z ) O ₃ is set to x = 0.15, y = 0.03, and z
4 is a chart showing a change in the reduction expansion coefficient when the value is varied.

FIG. 8 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
_y Co _z ) O ₃ is set to x = 0.15, y = 0.03, and z
4 is a chart showing a change in conductivity when the value is changed.

FIG. 9 shows (La _1-x Sr _x ) (Cr _1-yz Ti) of the present invention.
_y Co _z ) O ₃ is set to x = 0.15, y = 0.03, and z
6 is a chart showing a change in a coefficient of thermal expansion when the value is changed.

FIG. 10 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ where x ′ = 0.2 and z ′ = 0,
The chart which shows the fluctuation | variation of the reduction expansion coefficient at the time of changing y '.

FIG. 11 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ where x ′ = 0.2 and z ′ = 0,
The chart which shows the change of the electric conductivity when y 'was changed.

FIG. 12 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ where x ′ = 0.2 and z ′ = 0,
The chart which shows the fluctuation | variation of a thermal expansion coefficient when y 'is fluctuated.

FIG. 13 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ y ′ = 0.1, z ′ = 0,
The chart which shows the fluctuation | variation of the reduction expansion coefficient at the time of changing x '.

FIG. 14 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ y ′ = 0.1, z ′ = 0,
9 is a table showing a change in conductivity when x ′ is changed.

FIG. 15 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ y ′ = 0.1, z ′ = 0,
The chart which shows the fluctuation | variation of a thermal expansion coefficient when x 'is fluctuated.

FIG. 16 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ x ′ = 0.15, y ′ = 0.03
FIG. 4 is a table showing a change in the reduction expansion coefficient when z ′ is changed.

FIG. 17 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ x ′ = 0.15, y ′ = 0.03
FIG. 4 is a table showing a change in conductivity when z ′ is changed.

FIG. 18 shows (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} ) of the present invention.
Ti _{y ′} Ni _{z ′} ) O ₃ x ′ = 0.15, y ′ = 0.03
And a chart showing the variation of the coefficient of thermal expansion when z 'is varied.

FIG. 19 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for x "= 0.2, z" = 0,
The chart which shows the fluctuation | variation of the reduction expansion coefficient at the time of changing y ".

FIG. 20 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for x "= 0.2, z" = 0,
The chart which shows the fluctuation | variation of the electric conductivity when y "is changed.

FIG. 21 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for x "= 0.2, z" = 0,
The chart which shows the change of a coefficient of thermal expansion when y "is changed.

FIG. 22 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for y "= 0.1, z" = 0,
The chart which shows the fluctuation | variation of the reduction expansion coefficient at the time of changing x ".

FIG. 23 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for y "= 0.1, z" = 0,
The chart which shows the change of the electric conductivity when x "is changed.

FIG. 24 shows (La _{1-x "} Sr _x" ) (Cr _{1-y "-z"} ) of the present invention.
And _{Ti y "Fe z") O} 3 for y "= 0.1, z" = 0,
The chart which shows the fluctuation | variation of a thermal expansion coefficient when x "is fluctuated.

FIG. 25 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
_{Ti y "Fe z") O} 3 for x "= 0.15, y" = 0.03
And a chart showing the variation of the reduction expansion coefficient when z ″ is varied.

FIG. 26 shows (La _{1 -x "} Sr _x" ) (Cr _{1 -y "-z"} ) of the present invention.
_{Ti y "Fe z") O} 3 for x "= 0.15, y" = 0.03
FIG. 4 is a table showing a change in conductivity when z ″ is changed.

FIG. 27 shows (La _{1-x "} Sr _x" ) (Cr _{1-y "-z"} ) of the present invention.
_{Ti y "Fe z") O} 3 for x "= 0.15, y" = 0.03
And a chart showing the variation of the coefficient of thermal expansion when z ″ is varied.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Takenobu 1-1-1 Wadazakicho, Hyogo-ku, Kobe-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Kobe Shipyard (72) Inventor Fusayuki Nanjo, Hyogo-ku, Kobe-shi, Hyogo 1-1-1 Wadazakicho Mitsubishi Heavy Industries, Ltd., Kobe Shipyard

Claims (3)

[Claims] (1) (La_1-xSr_x) (Cr_1-yzTi_y
Co_z) O_Three(However, 0.1 ≦ x ≦ 0.2, 0.01 ≦
y ≦ 0.1, 0.01 ≦ z ≦ 0.05)
Characterized by lanthanum chromite material
And Y_TwoO _ThreeStabilized ZrO_TwoWith electricity as solid electrolyte
Interconnector material for chemical cells. 2. (La _{1-x ′} Sr _{x ′} ) (Cr _{1-y′-z ′} Ti
_{y ′} Ni _{z ′} ) O ₃ (0.1 ≦ x ′ ≦ 0.2, 0.0
(1 ≦ y ′ ≦ 0.05, 0.01 ≦ z ′ ≦ 0.08) Y ₂ O ₃ -stabilized ZrO ₂ characterized by being composed of a lanthanum chromite material represented by the general formula: Interconnector material for electrochemical cells. (La1 _{-x "} Srx _" ) (Cr1 _{-y "-z"} Ti
_{y "Fe z") O 3} ( where, 0.1 ≦ x "≦ 0.2,0.0
(1 ≦ y ″ ≦ 0.05, 0.01 ≦ z ″ ≦ 0.05) The solid electrolyte is made of a lanthanum chromite material represented by the general formula: Y ₂ O ₃ -stabilized ZrO _2. Interconnector material for electrochemical cells.