WO2019160019A1

WO2019160019A1 - Solid electrolyte assembly

Info

Publication number: WO2019160019A1
Application number: PCT/JP2019/005290
Authority: WO
Inventors: 勇介城; 慎吾井手; 旬春大山; 康博瀬戸; 八島　勇; 和夫篠崎; 忠塩田; 翔一山本
Original assignee: 三井金属鉱業株式会社
Priority date: 2018-02-14
Filing date: 2019-02-14
Publication date: 2019-08-22
Also published as: JP7300440B2; JPWO2019160019A1; TW201937509A

Abstract

A solid electrolyte assembly (10), formed by joining: a polycrystalline solid electrolyte (11) having oxide ion conductivity; and a mixed conduction electrode layer (12), which is laminated on the solid electrolyte (11) so as to be in contact and which has oxide ion conductivity and electron conductivity. The material constituting the solid electrolyte (11) and the material constituting the mixed conduction electrode layer (12) are uniaxially oriented in the direction of lamination of the solid electrolyte (11) and the mixed conduction electrode layer (12). The c-axis of the material constituting the solid electrolyte (11) and the c-axis of the material constituting the mixed conduction electrode layer (12) are preferably both oriented along the direction of lamination.

Description

Solid electrolyte assembly

The present invention relates to a solid electrolyte assembly having oxide ion conductivity. The solid electrolyte assembly of the present invention is used in various fields using its oxygen ion conductivity.

Various oxide ion conductive solid electrolytes are known. Such solid electrolytes are used in various fields, for example, as oxygen permeable elements, fuel cell electrolytes, and gas sensors. For example, Patent Document 1 includes a general formula: La _1-X Sr _X Ga _1-Y Mg _Y O ₃ (where X = 0.05 to 0.3, Y = 0.025 to 0.3). There is described an electrolyte membrane for an electrochemical cell comprising an oxide ion conductor having a composition as described above and having a perovskite crystal structure. This electrolyte film has a columnar crystal structure that grows in a direction perpendicular to the film surface and grows to the film surface. In the columnar crystal structure grown to the film surface, the 112 direction is oriented perpendicular to the film surface.

In Patent Document 2, an apatite-type crystal is formed in the vicinity of a bonding interface in which a first layer mainly composed of La ₂ SiO ₅ and a second layer mainly composed of La ₂ Si ₂ O ₇ are brought into contact with each other. A crystal-oriented ceramic is described in which a lanthanum silicate having a structure is produced, and the crystal of the lanthanum silicate is oriented along the vertical direction with respect to the original bonding interface.

Patent Document 3 describes an electrolyte / electrode assembly in which a solid electrolyte made of an apatite complex oxide is interposed between an anode side electrode and a cathode side electrode. An intermediate layer in which oxide ion conduction is isotropic is interposed between the cathode side electrode and the solid electrolyte. The intermediate layer is made of cerium oxide doped with samarium, yttrium, gadolinium or lanthanum. The solid electrolyte is made of La _x Si ₆ O _{1.5X + 12} (8 ≦ X ≦ 10). According to this electrolyte / electrode assembly, this document describes that the power generation performance of a solid oxide fuel cell is improved.

JP 2008-10411 A International Publication 2012/015061 JP2013-51101A

As described in Patent Documents 1 to 3, although various devices using oxide ion conductive solid electrolytes have been proposed, the oxide ions inherently possessed by the solid electrolyte when evaluated as a whole device. It could not be said that the conductivity was drawn sufficiently.

Therefore, an object of the present invention is to provide a device that can fully utilize the oxide ion conductivity inherently possessed by a solid electrolyte.

The present inventor has intensively studied to solve the above-mentioned problems. As a result, the solid electrolyte is inherently present by joining a material to the oxide ion conductive solid electrolyte so that a specific state is obtained. It has been found that the oxide ion conductivity can be sufficiently extracted.

The solid electrolyte assembly of the present invention has been made on the basis of the above findings, and is a polycrystalline solid electrolyte having oxide ion conductivity, laminated in contact with the solid electrolyte, and oxide ion conductivity and electronic conductivity. A mixed conductive electrode layer having
In both the material constituting the solid electrolyte and the material constituting the mixed conductive electrode layer, the solid electrolyte and the mixed conductive electrode layer are uniaxially oriented along the stacking direction. The above-described problems are solved by providing such a solid electrolyte assembly.

FIG. 1 is a schematic view of a cross section along the thickness direction showing an embodiment of a device using the solid electrolyte assembly of the present invention.

Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. As shown in FIG. 1, the solid electrolyte assembly 10 of the present invention includes a layer (hereinafter referred to as “solid electrolyte layer”) 11 made of a solid electrolyte. The solid electrolyte layer 11 is made of a solid electrolyte having oxide ion conductivity at a predetermined temperature or higher. On one surface of the solid electrolyte layer 11, an electrode layer (hereinafter referred to as “mixed conductive electrode layer”) 12 having a mixed conductivity laminated in contact with the solid electrolyte layer 11 is joined. In the embodiment shown in FIG. 1, the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are in direct contact with each other, and no other layer is interposed therebetween. The mixed conductive electrode layer 12 is made of a material having oxide ion conductivity and electronic conductivity. A solid electrolyte assembly 10 is constituted by the solid electrolyte layer 11 and the mixed conductive electrode layer 12.

As shown in FIG. 1, a metal electrode 13 may be further disposed on the surface opposite to the surface on which the mixed conductive electrode layer 12 is disposed, of the two surfaces of the solid electrolyte layer 11. In this case, the device 20 is configured by arranging the solid electrolyte layer 11, the mixed conductive electrode layer 12 and the metal electrode 13 in this order. In the embodiment shown in FIG. 1, the solid electrolyte layer 11 and the metal electrode 13 are in direct contact with each other, and no other layer is interposed therebetween.

In FIG. 1, the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are shown in different sizes, but the magnitude relationship between them is not limited to this, and for example, the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are the same. It may be a size. The same applies to the solid electrolyte layer 11 and the metal electrode 13, and both may be the same size, or for example, the size of the solid electrolyte layer 11 may be larger than that of the metal electrode 13.

As a result of the study by the present inventors, in the solid electrolyte assembly 10, the electric resistance between the solid electrolyte layer 11 and the mixed conductive electrode layer 12 is greatly reduced by bonding the mixed conductive electrode layer 12 to the solid electrolyte layer 11. It has been found that it can be made. Moreover, in order to reduce the electrical resistance in the device 20, it is thought that it is first important to increase the oxide ion conductivity of the solid electrolyte layer 11, but the device 20 is made using a material having high oxide ion conductivity. It has been found that the electrical resistance of the entire device 20 tends to increase. In particular, when a solid electrolyte layer containing a lanthanum oxide, which is one of materials having high oxide ion conductivity, is used as the solid electrolyte layer, the electrical resistance increases, and oxygen permeation through the solid electrolyte assembly 10 is increased. The knowledge that the speed tends to decrease was obtained. The reason for this is not clear at present, but the present inventor believes that it may be due to the high electrical resistance at the interface between the solid electrolyte layer and the electrode or mixed conductive electrode layer disposed adjacent thereto. thinking.

As a result of extensive studies by the present inventor to solve the problem of an increase in electrical resistance in the device 20 and a decrease in oxygen permeation rate resulting therefrom, the solid electrolyte layer 11 which is a layer having oxide ion conductivity is adjacent to the device 20. As the layer to be disposed, the mixed conductive electrode layer 12 having oxide ion conductivity and electronic conductivity is adopted, and the material constituting the solid electrolyte layer 11 and the material constituting the mixed conductive electrode layer 12 are Also, it has been found that it is effective that the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are uniaxially oriented along the stacking direction. As a result, the device 20 can be operated at a low temperature, or the device 20 having a high oxygen permeation amount can be obtained. On the other hand, even if the material constituting the solid electrolyte layer 11 and / or the material constituting the mixed conductive electrode layer 12 is non-oriented or the crystals of both layers are oriented, If any of the orientation directions is not coincident with the stacking direction, the electrical resistance at the interface between the solid electrolyte layer 11 and the mixed conductive electrode layer 12 becomes high, and high oxide ion conductivity is exhibited. It will not be a thing.

In order to align the material constituting the solid electrolyte layer 11 and the material constituting the mixed conductive electrode layer 12 uniaxially along the laminating direction, for example, the solid electrolyte layer 11 serving as a substrate is heated to 300 ° C. to 700 ° C. A thin film of the mixed conductive electrode layer 12 is formed on the solid electrolyte layer 11 using a physical vapor deposition method or a chemical vapor deposition method in an atmosphere in which the oxygen partial pressure is controlled while heating to 0 ° C. Epitaxial growth may be performed. In addition, a uniaxially oriented thin film of the mixed conductive electrode layer 12 can be formed on the solid electrolyte layer 11 by using atomic layer deposition (ALD). However, it is not limited to these methods.

Whether or not the material constituting the solid electrolyte layer 11 and the material constituting the mixed conductive electrode layer 12 are uniaxially oriented is determined from cross-sectional observation by a TEM (transmission electron microscope) of the bonding interface. The lattice constants and plane spacings of the solid electrolyte layer 11 and the mixed conductive electrode layer 12 can be calculated from a diffraction pattern obtained by performing X-ray diffraction measurement while swinging.

From the viewpoint of obtaining higher oxide ion conductivity, the c-axis of the material constituting the solid electrolyte layer 11 and the c-axis of the material constituting the mixed conductive electrode layer 12 are both mixed with the solid electrolyte layer 11. The orientation is preferably along the direction of lamination with the electrode layer 12. Here, the c-axis being oriented along the stacking direction means that the direction in which the c-axis extends in each crystal of the solid electrolyte that is a polycrystal coincides with the direction in which the layers are stacked. Say.

The solid electrolyte layer 11 is a conductor in which oxide ions are carriers. A polycrystalline material is used as the solid electrolyte constituting the solid electrolyte layer 11. Examples of such materials include various materials known so far as materials having oxide ion conductivity. For example, yttria stabilized zirconium (YSZ), lanthanum gallate (LaGaO ₃ ), and the like can be given.

In particular, it is preferable to use an oxide of lanthanum as the material constituting the solid electrolyte layer 11 because the oxide ion conductivity is further increased. Examples of the lanthanum oxide include a composite oxide containing lanthanum and gallium, a composite oxide obtained by adding strontium, magnesium, cobalt, or the like to the composite oxide, or a composite oxide containing lanthanum and molybdenum. In particular, since the oxide ion conductivity is high, it is preferable to use an oxide ion conductive material made of a complex oxide of lanthanum and silicon.

As a complex oxide of lanthanum and silicon, for example, an apatite complex oxide containing lanthanum and silicon can be given. The apatite-type composite oxide contains lanthanum, which is a trivalent element, silicon, which is a tetravalent element, and O, and its composition is La _x Si ₆ O _{1.5x + 12} (X is a number of 8 or more and 10 or less. Is preferable from the viewpoint of high oxide ion conductivity. When this apatite-type composite oxide is used as the solid electrolyte layer 11, it is preferable that the c-axis coincide with the thickness direction of the solid electrolyte layer 11. The most preferred composition of this apatite type complex oxide is La _9.33 Si ₆ O ₂₆ . This composite oxide can be produced, for example, according to the method described in JP2013-51101A.

Another example of the material constituting the solid electrolyte layer 11 is a composite oxide represented by the general formula (1): A _{9.33 + x} [T _6.00- _{y My} ] O _{26.0 + z} . This composite oxide also has an apatite structure. A in the formula is one or more elements selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Be, Mg, Ca, Sr and Ba. T in the formula is an element containing Si or Ge or both. M in the formula is one or more elements selected from the group consisting of B, Ge, Zn, Sn, W and Mo. From the viewpoint of enhancing the c-axis orientation, M is preferably one or more elements selected from the group consisting of B, Ge, and Zn.

In the formula, x is preferably −1.00 or more and 1.00 or less, more preferably 0.00 or more and 0.70 or less, from the viewpoint of improving the degree of orientation and oxide ion conductivity. More preferably, it is from 45 to 0.65. Y in the formula is preferably 0.40 or more and 3.00 or less, more preferably 0.40 or more and 2.00 or less, from the viewpoint of filling the T element position in the apatite type crystal lattice. More preferably, it is 40 or more and 1.00 or less. In the formula, z is preferably −3.00 or more and 2.00 or less, and −2.00 or more and 1.50 or less from the viewpoint of maintaining electrical neutrality in the apatite crystal lattice. Is more preferably -1.00 or more and 1.00 or less.

In the above formula, the ratio of the number of moles of A to the number of moles of M, in other words, (9.33 + x) / y in the formula is 3.00 or more and 26 from the viewpoint of maintaining the spatial occupancy in the apatite type crystal lattice. It is preferably 0.0 or less, more preferably 6.20 or more and 26.0 or less, and still more preferably 12.00 or more and 16.0 or less.

Of the complex oxides represented by the general formula (1), a complex oxide in which A is lanthanum, that is, a complex oxide represented by La _{9.33 + x} [T _6.00- _{y My} ] O _{26.0 + z} When used, it is preferable from the viewpoint of further increasing the oxide ion conductivity. Specific examples of the _{_{La 9.33 + x [T 6.00-}} y M y] O 26.0 + z composite oxide represented _{_{by, La 9.33 + x (Si 4.70}} B 1.30) O 26.0 + z, La 9.33 + x (Si 4.70 Ge _1.30 ) O _{26.0 + z} , La _{9.33 + x} (Si _4.70 Zn _1.30 ) O _{26.0 + z} , La _{9.33 + x} (Si _4.70 W _1.30 ) O _{26.0 + z} , La _{9.33 + x} (Si _4.70 Sn _1.30 ) O _{26.0 + x} , La _{9.33 + x} (Ge _4.70 B _1.30 ) O _{26.0 + z, and the} like. The composite oxide represented by the general formula (1) can be produced, for example, according to the method described in International Publication WO2016 / 111110.

The thickness of the solid electrolyte layer 11 is preferably 10 nm or more and 1000 μm or less, more preferably 50 nm or more and 700 μm or less, and more preferably 100 nm or more and 500 μm or less from the viewpoint of effectively reducing the electric resistance of the solid electrolyte assembly 10. It is more preferable that The thickness of the solid electrolyte layer 11 can be measured using, for example, a stylus type step meter or an electron microscope.

The mixed conductive electrode layer 12 is made of a material having oxide ion conductivity and electronic conductivity. In particular, the mixed conductive electrode layer 12 is preferably made of a material having a catalytic action. The catalytic action here means an action of reducing oxygen molecules (O ₂ ) to oxide ions (O ²⁻ ) and an action of oxidizing oxide ions (O ²⁻ ) to oxygen molecules (O ₂ ). It is. Examples of such materials include (La, Sr) MnO ₃ , (La, Sr) CoO ₃ , (La, Sr) (Co, Sc) in which a part of atoms such as LaCoO ₃ and LaMnO ₃ is substituted with other atoms. Fe) O _{3 and the} like.

In the solid electrolyte assembly 10, the material constituting the mixed conductive electrode layer 12 and the material constituting the solid electrolyte layer 11 described above are both in the stacking direction of the solid electrolyte layer 11 and the mixed conductive electrode layer 12. By being uniaxially oriented along, the electric resistance at the interface between both

layers

11 and 12 is reduced. From the viewpoint of making this advantage even more prominent, it is advantageous to achieve lattice matching in a plane orthogonal to the orientation direction at the interface between the two

layers

11 and 12. For example, when the c-axis of the material constituting each of the

layers

11 and 12 is oriented along the stacking direction, it is preferable that lattice matching is performed on a plane orthogonal to the c-axis. In this case, either the a-axis or b-axis lattice constant of the mixed conductive electrode layer 12 or the spacing between the planes may be matched with that of the solid electrolyte layer 11. Furthermore, even when the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are not matched, the lattice orthogonal to the orientation direction of the solid electrolyte layer 11 can be obtained by heating the solid electrolyte assembly 10. Depending on the constant or face spacing, the lattice constant or face spacing of the mixed conducting electrode layer 12 can be matched, thereby allowing uniaxially oriented crystals to grow. From this point of view, when the lattice constant of the surface perpendicular to the c-axis of the material constituting the solid electrolyte layer 11 is a and the interplanar spacing at (010) of the mixed conductive electrode layer 12 is d, a is 9.28 mm or more. It is preferable that it is 9.84 mm or less. Further, d is preferably 4.54 to 5.04, more preferably 4.60 to 4.97, and still more preferably 4.64 to 4.92.

The lattice constant and interplanar spacing d of the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are diffraction peaks obtained by performing X-ray diffraction measurement while the mixed conductive electrode layer 12 is joined to the solid electrolyte layer 11 and then swung. Calculated from The X-ray diffraction measurement conditions at this time are Cu-Kα rays, diffraction angle (2θ / θ) of 10 ° to 140 °, tilt angle (χ swing) of -5 ° to 45 °, in-plane rotation (φ swing) ) Was set to 0 to 360 °.

Furthermore, when the type and composition ratio of the elements contained in the sample are known, the lattice constant a and the spacing d are calculated based on the diffraction data of the standard material such as ICSD® (inorganic crystal structure database). You can also. For example, when the crystal form of the solid electrolyte layer 11 is a hexagonal crystal and the lattice constant a is 9.60 Å, the (110) plane spacing of the solid electrolyte layer 11 is 4.80 Å. When the (010) plane spacing of the mixed conductive electrode layer 12 is d = 4.70 mm, the lattice mismatch of the plane orthogonal to the c-axis is as low as 2.2%. The electrode layer 12 is considered to be locally epitaxially grown.

From the viewpoint of achieving lattice matching of the plane orthogonal to the orientation direction at the interface between the solid electrolyte layer 11 and the mixed conductive electrode layer 12, the material constituting the mixed conductive electrode layer 12 is preferably a perovskite oxide. . In particular, when the material constituting the solid electrolyte layer 11 is represented by the general formula (1) described above, the lattice matching is successfully achieved when the material constituting the mixed conductive electrode layer 12 is a perovskite oxide. I can plan well. In this case, it is preferable that the space group of the perovskite oxide is R-3c because lattice matching can be achieved more successfully.

In particular, it is preferable to use a material represented by the general formula (2): ABO ₃ as a material constituting the mixed conductive electrode layer 12 from the viewpoint of further improving the oxide ion conductivity. In the formula, A is preferably one or more metal elements selected from, for example, La, Sr, Ba, and Ca, and a particularly preferable metal element is at least one of La and Sr. B preferably uses, for example, one or more metal elements selected from Co, Ni, Mn, Cr, Ti, Fe, and Cu, and a particularly preferable metal element is at least one of Co and Ni. It is a seed. In particular, the material represented by the general formula (2) is preferably a composite oxide containing La, Sr, Co, and Ni.

Among the complex oxides represented by the general formula (2), a particularly preferable one is represented by La _0.6 Sr _0.4 Co _0.9 Ni _0.1 O _3-δ .

The mixed conductive electrode layer 12 made of the complex oxide represented by the general formula (2) can be formed on one surface of the solid electrolyte layer 11 by using various thin film forming methods, for example. Examples of the thin film forming method include physical vapor deposition and chemical vapor deposition. Among these, the mixed conductive electrode layer 12 can be formed more successfully by using physical vapor deposition. Among physical vapor deposition methods, it is particularly preferable to use a PLD (Pulsed Laser Deposition) method.

As a result of the inventor's examination, the mixed conductive electrode layer 12 can effectively reduce the electric resistance between the mixed conductive electrode layer 12 and the solid electrolyte layer 11 if it has a predetermined thickness. Specifically, the thickness along the stacking direction of the mixed conductive electrode layer 12 bonded to the solid electrolyte layer 11 is preferably 80 nm or more, more preferably 100 nm or more, and 100 nm or more and 1000 nm or less. Even more preferred. The thickness of the mixed conductive electrode layer 12 can be measured with a stylus profilometer or an electron microscope.

The metal electrode 13 formed on the opposite side of the mixed conductive electrode layer 12 with the solid electrolyte layer 11 interposed therebetween is advantageous in that it is easy to form and has high catalytic activity. Preferably, it is configured. Examples of the platinum group element include platinum, ruthenium, rhodium, palladium, osmium, and iridium. These elements can be used individually by 1 type or in combination of 2 or more types. Further, a cermet containing a platinum group element can be used as the metal electrode 13.

The solid electrolyte joined body 10 and the device 20 of the embodiment shown in FIG. 1 can be suitably manufactured by, for example, the method described below. First, the solid electrolyte layer 11 is manufactured by a known method. For the production, for example, the methods described in JP2013-51101A and International Publication WO2016 / 111110 described above can be employed.

Next, the mixed conductive electrode layer 12 is formed on one of the two surfaces of the solid electrolyte layer 11. For example, the PLD method described above can be used to form the mixed conductive electrode layer 12. Specifically, the material constituting the solid electrolyte layer 11 and the material constituting the mixed conductive electrode layer 12 are uniaxially oriented along the stacking direction of the solid electrolyte layer 11 and the mixed conductive electrode layer 12. Therefore, when the mixed conductive electrode layer 12 is formed on one surface of the solid electrolyte layer 11 using the PLD method described above, the solid electrolyte layer 11 may be heated to a predetermined temperature. The heating temperature is preferably set to, for example, 600 ° C. or more and 700 ° C. or less from the viewpoint that the uniaxial orientation can be achieved more successfully.
When the mixed conductive electrode layer 12 is formed in this way, the metal electrode 13 is formed on the surface of the solid electrolyte layer 11 opposite to the surface on which the mixed conductive electrode layer 12 is formed. For example, a paste containing platinum group metal particles is used to form the metal electrode 13. The paste is applied to the surface of the solid electrolyte layer 11 to form a coating film, and the coating film is baked to form an electrode made of a porous body. Firing conditions can be a temperature of 600 ° C. or more and a time of 30 minutes or more and 120 minutes or less. The atmosphere can be an oxygen-containing atmosphere such as air.

The target solid electrolyte joined body 10 and the device 20 are obtained by the above method. The device 20 thus obtained is suitably used as, for example, an oxygen permeable element, an oxygen sensor, or a solid oxide fuel cell using the high oxide ion conductivity. Whatever the application of the device 20, it is advantageous to use the mixed conductive electrode layer 12 as a cathode, that is, as an electrode where an oxygen gas reduction reaction takes place. For example, when the device 20 is used as an oxygen permeable element, the metal electrode 13 is connected to the anode of the direct current power source, and the mixed conductive electrode layer 12 is connected to the cathode of the direct current power source. A predetermined DC voltage is applied between Thereby, oxygen receives electrons on the mixed conductive electrode layer 12 side and oxide ions are generated. The generated oxide ions move through the solid electrolyte layer 11 and reach the metal electrode 13. The oxide ions reaching the metal electrode 13 emit electrons and become oxygen gas. By such a reaction, the solid electrolyte layer 11 can transmit the oxygen gas contained in the atmosphere on the mixed conductive electrode layer 12 side to the electrode 13 side through the solid electrolyte layer 11. If necessary, a current collecting layer made of a conductive material such as platinum may be formed on at least one of the surface of the mixed conductive electrode layer 12 and the surface of the metal electrode 13.

The applied voltage is preferably set to 0.1 V or more and 4.0 V or less from the viewpoint of increasing the permeation amount of oxygen gas. When applying a voltage between both electrodes, it is preferable that the oxide ion conductivity of the solid electrolyte layer 11 is sufficiently high. For example, the oxide ion conductivity is preferably 1.0 × 10 ⁻³ S / cm or more in terms of conductivity. For this reason, it is preferable to hold the solid electrolyte layer 11 or the entire device 20 at a predetermined temperature. Although this holding temperature depends on the material of the solid electrolyte layer 11, it is generally preferable to set it within a range of 300 ° C. or more and 600 ° C. or less. By using the device 20 under these conditions, oxygen gas contained in the atmosphere on the mixed conductive electrode layer 12 side can be transmitted through the solid electrolyte layer 11 to the metal electrode 13 side.

When the device 20 is used as a limiting current type oxygen sensor, the oxide ions generated on the mixed conductive electrode layer 12 side move to the metal electrode 13 side via the solid electrolyte layer 11, resulting in a current. Occurs. Since the current value depends on the oxygen gas concentration on the mixed conduction electrode layer 12 side, the oxygen gas concentration on the mixed conduction electrode layer 12 side can be measured by measuring the current value.

As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the above-described embodiment, the mixed conductive electrode layer 12 is disposed only on one surface of the solid electrolyte layer 11, but instead of this, as described in Examples described later, the mixed conductive electrode layer 11 is included in the solid electrolyte layer 11. A separate mixed conductive electrode layer 12 may be disposed on the surface facing the substrate 12. When the mixed conductive electrode layer 12 is disposed on the surface of the solid electrolyte layer 11 facing the mixed conductive electrode layer 12, the mixed conductive electrode layers 12 may be the same or different. Also good. In this case, the material constituting the solid electrolyte layer 11, the material constituting one mixed conductive electrode layer 12, and the material constituting the other mixed conductive electrode layer 12 are all along the stacking direction thereof. Uniaxial orientation is preferred.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass%”.

[Example 1]
In this example, the solid electrolyte joined body 10 and the device 20 having the structure shown in FIG. 1 were manufactured according to the following steps (1) to (4).
(1) Production of Solid Electrolyte Layer 11 La ₂ O ₃ powder and SiO ₂ powder were blended at a molar ratio of 1: 1, ethanol was added, and the mixture was mixed by a ball mill. The mixture was dried, ground in a mortar and fired at 1650 ° C. for 3 hours in an atmospheric atmosphere using a platinum crucible. Ethanol was added to the fired product and pulverized with a ball mill to obtain a fired powder. The fired powder was put into a 20 mmφ molding machine and pressed from one direction to be uniaxially molded. Further, cold isostatic pressing (CIP) was performed at 700 MPa for 1 minute to form pellets. This pellet-shaped molded body was heated in the atmosphere at 1600 ° C. for 3 hours to obtain a pellet-shaped sintered body. When this sintered body was subjected to powder X-ray diffraction measurement and chemical analysis, it was confirmed to have a La ₂ SiO ₅ structure.

800 mg of the obtained pellets and 140 mg of B ₂ O ₃ powder were placed in a jar with a lid, and heated at 1550 ° C. (furnace atmosphere temperature) in the air for 50 hours using an electric furnace. By this heating, B ₂ O ₃ vapor is generated in the mortar and the B ₂ O ₃ vapor and the pellet are reacted, and then annealed in the atmosphere at 1600 ° C., so that the intended solid electrolyte layer is obtained. 11 was obtained. This solid electrolyte layer 11 has La _{= 0.33 + x} [Si _6.00-y B _y ] O _{26.0 + z} , where x = 0.57, y = 0.96, z = 0.37, and the molar ratio of La and B Was 10.03 (hereinafter, this compound is abbreviated as “LSBO”). The oxide ion conductivity at 500 ° C. was 4.22 × 10 ⁻² S / cm. The thickness of the solid electrolyte layer 11 was 350 μm. From observation with a polarizing microscope, it was confirmed that the solid electrolyte layer 11 was composed of a polycrystal.

(2) Manufacture of Mixed Conductive Electrode Layer 12 The mixed conductive electrode layer 12 was formed on one surface of the solid electrolyte layer 11 manufactured in (1) by the following procedure.
Set solid electrolyte layer 11 and target La _0.6 Sr _0.4 Co _0.9 Ni _0.1 O _3-δ (hereinafter, this substance is abbreviated as “LSCNO”) into the chamber of the PLD apparatus. Then, heating was performed in advance at 600 ° C. while evacuating the chamber. Thereafter, oxygen is introduced into the chamber and the atmosphere is controlled so as to be 5.5 × 10 ⁻⁴ torr, and then evaporated particles generated by laser ablation are deposited on the solid electrolyte layer 11 using a KrF excimer laser. Thus, a mixed conductive electrode layer 12 was formed. The mixed conductive electrode layer 12 thus obtained was confirmed to be composed of a polycrystalline body by TEM cross-sectional observation of the interface with the solid electrolyte layer 11. The distance between the (110) plane of the solid electrolyte layer 11 and the (010) plane of the mixed conductive electrode layer 12 is the same, and the c axis of the material constituting the solid electrolyte layer 11 and the mixed conductive electrode layer 12 are configured. It was confirmed that the c-axis of the material to be oriented was aligned along the stacking direction. Further, as a result of X-ray diffraction measurement while shaking, it was confirmed that the mixed conductive electrode layer 12 was a perovskite oxide having a space group of R-3c. Furthermore, the plane spacing of the (110) plane of the solid electrolyte layer 11 calculated based on the lattice constant obtained from the diffraction pattern is 4.80 mm, and the plane spacing of the (010) plane of the mixed conductive electrode layer 12 is It was 4.68 cm. The lattice mismatch was 2.45%.

(3) Manufacture of the metal electrode 13 The metal electrode 13 was formed in the surface on the opposite side to the surface in which the mixed conductive electrode layer 12 was formed among the solid electrolyte layers 11 manufactured by (1). The metal electrode 13 was formed by sputtering using a platinum target. A metal film 13 was obtained by annealing a platinum film formed on the surface of the solid electrolyte layer 11 opposite to the surface on which the mixed conductive electrode layer 12 was formed by sputtering at 600 ° C. for 1 hour. The thickness of the metal electrode 13 was 100 nm.

(4) Manufacture of current collection layer A platinum paste was applied to the surfaces of the mixed conductive electrode layer 12 and the metal electrode 13 to form a coating film. These coating films were baked at 600 ° C. for 1 hour in the air to obtain a current collecting layer.

[Example 2]
Instead of the step (3) of Example 1, the step (2) of the same example was performed to obtain a device 20 in which the mixed conductive electrode layer 12 was disposed on each surface of the solid electrolyte layer 11.

[Comparative Example 1]
In the step (2) of Example 1, the mixed conductive electrode layer 12 was formed at room temperature. Except this, it carried out similarly to Example 1, and obtained the solid electrolyte conjugate | zygote 10 and the device 20. FIG. In this solid electrolyte assembly 10, it was confirmed by X-ray diffraction measurement that the mixed conductive electrode layer 12 was not uniaxially oriented.

[Comparative Example 2]
In this comparative example, a paste containing LSCNO was applied to each surface of the solid electrolyte layer 11 obtained in the step (1) of Example 1 to form a coating film. By baking for a period of time, the mixed conductive electrode layer 12 having a thickness of 300 nm or more was formed.

[Comparative Example 3]
In this comparative example, the solid electrolyte layer 11 that performs the process (1) of Example 1 was formed. Next, the step (3) of the same example was performed, and a metal electrode 13 made of platinum was formed in the solid electrolyte layer 11 instead of the mixed conductive electrode layer 12 of the first example. A metal electrode 13 made of platinum was also formed on the opposite surface. The thickness of the metal electrode 13 was 100 nm or more.

[Evaluation]
About the device obtained by the Example and the comparative example, the oxygen transmission rate was measured with the following method. The presence or absence of crystal orientation of the solid electrolyte layer 11 and the mixed conductive electrode layer 12 was confirmed by X-ray diffraction measurement. The results are shown in Table 1 below.

(Measurement of oxygen transmission rate)
The measurement was performed at 600 ° C. Air is supplied to the mixed conductive electrode layer 12 side of the device and N ₂ gas is supplied to the metal electrode 13 side at 200 ml / min, respectively, and a DC voltage of 1.0 V is applied between the mixed conductive electrode layer 12 and the metal electrode 13. did. An oxygen concentration meter was attached to the metal electrode 13 side, a change in oxygen concentration in the atmosphere on the metal electrode 13 side before and after voltage application was measured, and an oxygen transmission rate (ml · cm ⁻² · min ⁻¹ ) was calculated. Further, the oxygen transmission efficiency was calculated by the formula [oxygen transmission amount measured with an oxygen concentration meter] / [oxygen transmission amount measured from current density] × 100.

As is clear from the results shown in Table 1, it can be seen that the solid electrolyte assembly obtained in each Example and the device including the same have a high oxygen transmission rate and a high oxygen transmission efficiency.

According to the present invention, a solid electrolyte assembly having a high oxygen transmission rate is provided. By using this solid electrolyte assembly, the device can be operated at a low temperature and the oxygen supply amount can be increased.

Claims

A polycrystalline solid electrolyte having oxide ion conductivity and a mixed conductive electrode layer laminated in contact with the solid electrolyte and having oxide ion conductivity and electron conductivity are joined together,
The solid electrolyte assembly in which the material constituting the solid electrolyte and the material constituting the mixed conductive electrode layer are uniaxially oriented along the stacking direction of the solid electrolyte and the mixed conductive electrode layer .
The solid electrolyte assembly according to claim 1, wherein the mixed conductive electrode layer is polycrystalline.
3. The solid electrolyte bonding according to claim 1, wherein a c-axis of a material constituting the solid electrolyte and a c-axis of a material constituting the mixed conductive electrode layer are both oriented along the laminating direction. body.
The solid electrolyte assembly according to any one of claims 1 to 3, wherein the solid electrolyte is an apatite complex oxide.
Wherein the solid electrolyte has the general formula: A 9.33 + x [T 6.00 -y M y] O 26.0 + z (A in the formula, La, Ce, Pr, Nd , Sm, Eu, Gd, Tb, Dy, Be, One or two or more elements selected from the group consisting of Mg, Ca, Sr and Ba, wherein T is an element containing Si or Ge or both, wherein M is B, 1 or 2 or more elements selected from the group consisting of Ge, Zn, Sn, W and Mo.), and x in the formula is a number from −1.00 to 1.00, Y in the formula is a number from 0.40 to 3.00, z in the formula is a number from −3.00 to 2.00, and the ratio of the number of moles of A to the number of moles of M is 3 The solid electrolyte joined body according to any one of claims 1 to 4, comprising a composite oxide of 0.000 or more and 26.0 or less.
The solid electrolyte joined body according to any one of claims 1 to 5, wherein a (010) plane interval of the mixed conductive electrode layer is 4.54 mm or more and 5.04 mm or less.
The solid electrolyte assembly according to any one of claims 1 to 6, wherein the mixed conductive electrode layer is a perovskite oxide.
The solid electrolyte joined body according to claim 7, wherein the space group of the perovskite oxide is R-3c.
The solid electrolyte joined body according to any one of claims 1 to 8, wherein the mixed conductive electrode layer is a composite oxide containing La, Sr, Co, and Ni.
The solid electrolyte assembly according to any one of claims 1 to 9, wherein a thickness of the mixed conductive electrode layer bonded to the solid electrolyte along the stacking direction is 100 nm or more.
The solid electrolyte assembly according to any one of claims 1 to 10, wherein a metal electrode is disposed on a surface opposite to the surface on which the mixed conductive electrode layer is disposed in the solid electrolyte assembly.
The mixed conductive electrode layer which is the same as or different from the mixed conductive electrode layer is disposed on a surface of the solid electrolyte assembly opposite to the surface on which the mixed conductive electrode layer is disposed. The solid electrolyte joined body according to claim 1.
The solid electrolyte assembly according to any one of claims 1 to 12, which is used as an oxygen permeable element, an oxygen sensor, or a solid electrolyte fuel cell.