Hydrogen permeable materials

Abstract

The purpose of the present invention is to provide a hydrogen-permeable material having excellent hydrogen permeability. A further purpose of the present invention is to provide a composite member and fuel cell containing the hydrogen-permeable material. The hydrogen-permeable material contains a perovskite-structured compound represented by the following general formula (1a). In another embodiment, the hydrogen-permeable material comprises a hydrogen-containing perovskite-structured compound in which a hydride ion (H-) has been introduced into the perovskite-structured compound represented by the following general formula (1a). In the formula, M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, x is a numerical value of 0-0.3, y is a numerical value of more than 0 and 0.75 or less, w is a value at which the average valence of In is +1.0 to +2.5, and y ≧ w.

Description

[Technical Field]

[0001] This invention relates to a hydrogen permeable material and its use.

[0002] Cross-reference of related applications This application claims priority to Japanese Patent Application No. 2021-039946, filed on 12 March 2021, all of which are incorporated herein by reference. [Background technology]

[0003] Materials that selectively permeate hydrogen (hydrogen permeable materials) are useful not only as separation membranes for hydrogen production but also as fuel electrodes for thermal catalytic reactors and fuel cells. Methods using hydrogen permeable membranes made of hydrogen storage alloys have been investigated as such materials, but these alloys suffer from severe hydrogen embrittlement, causing the membrane structure to break down within a few hours of the start of hydrogen separation (Non-Patent Literature 1). Only Pd... 0.8 Ag 0.2 Pd alloy films such as those shown exhibit stable hydrogen permeability without causing serious hydrogen embrittlement (Non-Patent Documents 2 and 3). However, because Pd is a precious metal with limited reserves, there are many challenges for large-scale applications in terms of cost and stable supply.

[0004] Therefore, there is a need for hydrogen-permeable materials based on entirely new principles that can replace the hydrogen dissolution of metals.

[0005] Recently, polycrystalline TiN films have been reported as hydrogen permeable materials usable at relatively low temperatures (Non-Patent Documents 4 and 5). In addition, as hydrogen permeable materials other than Pd alloys that can be used in high-temperature environments, proton-conducting oxides (BaZr) have been reported. 1-x Ce 0.9-x M 0.2 By compounding O3 (M=Y, Sc, and rare earth metals) with electronically conductive metals (Ni, Cu, etc.), protons and electrons (H) are formed. + -e - Cermet materials with mixed conductivity are attracting attention (Non-Patent Literature 6).

[0006] Non-patent document 1: NAAl-Mufachi et al., Renewable and Sustainable Energy Reviews, 2015, 47, 540-551. Non-patent document 2: Donglai Xie et al., International Journal of Hydrogen Energy, 2011, 36, 1014-1026. Non-patent document 3: Gerhard L.Holleck, Journal of Physical Chemistry, 1970, 74, 503-511 Non-patent document 4: Chiharu Kura et al., Nature Energy, 2017, 2, 786-794. Non-patent document 5: Chiharu Kura et al., Journal of Materials Chemistry A, 2018, 6, 2730-2741. Non-patent document 6: N. Kochetova et al., RSC Advances, 2016, 6, 73222-73268 All contents of Non-Patent Documents 1-6 are incorporated herein by reference. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, in the cermet materials described above, the bond energy between oxygen and protons in the ceramic solid is very large at 50 kJ / mol, so high flux can only be generated in the temperature range above 700°C, and it is difficult to obtain sufficient hydrogen permeability in the temperature range below 600°C.

[0008] This invention has been made in view of the above problems, and aims to provide a novel hydrogen permeable material that has excellent hydrogen permeability even under typical hydrocarbon reforming process conditions, namely, a temperature range of 600°C or less and a water vapor-containing atmosphere.

[0009] Furthermore, the present invention aims to provide a means of utilizing the hydrogen permeable material of the present invention, and in particular to provide a fuel cell using the hydrogen permeable material of the present invention. [Means for solving the problem]

[0010] The present invention, which solves the above problems, is as follows. [1] A hydrogen permeable material containing a perovskite-type compound represented by the following general formula (1a). [ka] (In formula (1a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca.) x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is a value such that the average value of In is between +1.0 and +2.5. y ≥ w. [2] The hydrogen permeable material according to [1], wherein In is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valency of +3. [3] The perovskite compound represented by general formula (1a) is the hydrogen permeable material described in [2], represented by the following general formula (1b). [ka] [4] The perovskite compound represented by general formula (1a) contains In(II) and is a hydrogen permeable material as described in [2], represented by general formula (1c) or general formula (1d) below. [ka] [5] The average valency of In is the average valency determined from the mass change in the thermal analysis of the perovskite-type compound, as described in any one of [1] to [4] for hydrogen permeable materials. [6] [1] A perovskite compound represented by the general formula (1a) described above contains a hydride ion (H - A hydrogen permeable material containing a hydrogen-containing perovskite compound (hereinafter referred to as a hydrogen-containing perovskite compound), wherein the molar ratio of hydride ion content n to w (n / w) is 2 or less. [7] The above hydrogen-containing perovskite compound is represented by the following general formula (2a) and is a hydrogen permeable material as described in [6]. [ka] (In formula (2a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca.) H is a hydride ion, x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is the value at which the average value of In is greater than +1.0 and less than or equal to +3.0. y ≥ w, and n / w ≤ 2. [8] The hydrogen permeable material according to [7], wherein In is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valency of +3. [9] The hydrogen-containing perovskite compound represented by general formula (2a) is the hydrogen permeable material described in [8], represented by the following general formula (2b). [ka]

[10] The hydrogen-containing perovskite compound represented by general formula (2a) contains In(II) and is a hydrogen permeable material as described in [8], represented by general formula (2c) or general formula (2d) below. [ka]

[11] The hydrogen permeable material according to any one of [6] to

[10] , wherein the hydride ion content of the hydrogen-containing perovskite compound is determined by secondary ion mass spectrometry or neutron diffraction.

[12] A hydrogen permeable material containing a hydrate of a perovskite-type compound described in any one of [1] to [5] or a hydrate of a hydrogen-containing perovskite-type compound described in any one of [6] to

[11] .

[13] The hydrogen permeable material according to

[12] , wherein the above hydrate is a hydrate represented by any one of the following general formulas (3a) to (3d) or any one of the following general formulas (4a) to (4d). [ka] (Formula (3a) represents the hydrate of the compound shown in formula (1a), and M, x, y, and w in formula (3a) are equivalent to those in formula (1a), Formula (3b) represents the hydrate of the compound shown in formula (1b), where M, In(I), In(III), x, y, and w are equivalent to those in formula (1b). Formula (3c) represents the hydrate of the compound shown in formula (1c), where M, In(II), In(III), x, y, and w are equivalent to those in formula (1c). Formula (3d) represents the hydrate of the compound shown in formula (1d), and M, In(I), In(II), x, y, and w in formula (3d) are equivalent to those in formula (1d). Formula (4a) represents the hydrate of the compound shown in formula (2a), and the M, n-labeled H, x, y, w, and n in formula (4a) are equivalent to those in formula (2a). Formula (4b) represents a hydrate of the compound represented by formula (2b), and M, In(I), In(III), H with n, x, y, w, and n in formula (4b) have the same meanings as those in formula (2b). Formula (4c) represents a hydrate of the compound represented by formula (2c), and M, In(II), In(III), H with n, x, y, w, and n in formula (4c) have the same meanings as those in formula (2c). Formula (4d) represents a hydrate of the compound represented by formula (2d), and M, In(I), In(II), H with n, x, y, w, and n in formula (4d) have the same meanings as those in formula (2d). l is a positive number satisfying l < x + 0.5y + w. )

[14] The perovskite-type compounds represented by general formulas (1a) to (1d), the hydrogen-containing perovskite-type compounds represented by general formulas (2a) to (2d), or the hydrates represented by general formulas (3a) to (3d) or (4a) to (4d) are compounds in which part of the Zr and In, which are B-site elements, are substituted with at least one element selected from the group consisting of rare earth elements, Ni, and Zn, and are the hydrogen permeation materials described in any one of [1] to

[13] .

[15] A composite member having a hydrogen permeable layer made of the hydrogen permeation material described in any one of [1] to

[14] on at least a part of the surface of a porous substrate.

[16] The composite member according to

[15] , wherein the porous substrate is a cermet substrate and the ceramic component of the cermet substrate is the hydrogen permeation material described in any one of [1] to

[14] .

[17] A fuel cell having, in this order, an anode layer, an electrolyte layer, and a cathode layer containing the hydrogen permeation material described in any one of [1] to

[14] on at least a part of one main surface of a porous substrate.

[18] The fuel cell according to

[17] , wherein the porous substrate and the anode layer are the composite member described in

[15] or

[16] .

[19] The electrolyte layer is BaZr x Ce 1-x-z Yz A fuel cell as described in

[17] or

[18] , wherein O3 (x=0.1~0.8, z=0.1~0.25, x+z≦1.0).

[0011] Furthermore, this specification also discloses a method for producing perovskite-type compounds represented by general formulas (1a) to (1d) contained in the hydrogen permeable material described below, and a method for producing hydrogen-containing perovskite-type compounds in which hydride ions are introduced into the perovskite-type compound. [P1] A method for producing a perovskite compound, comprising heating a perovskite compound represented by the following general formula (5a) and / or its hydrate in a hydrogen atmosphere at 600°C or higher to obtain a perovskite compound represented by the following general formula (1a). [ka] (In the formula, M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca.) x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is a value such that the average value of In is between +1.0 and +2.5. (y≧w) [P2] The manufacturing method according to [P1], wherein In in formula (1a) is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valency of +3. [P3] The perovskite compound represented by general formula (1a) is represented by the following general formula (1b), and the method of production described in [P2]. [ka] [P4] The perovskite compound represented by general formula (1a) contains In(II) and is represented by the following general formula (1c) or general formula (1d), as described in the manufacturing method described in [P2]. [ka] [P5] The hydrogen atmosphere is water-free and is a manufacturing method as described in any one of [P1] to [P4]. [P6] A perovskite compound represented by the following general formula (1a) is exposed to a hydrogen atmosphere at a temperature of less than 600°C, and a hydride ion (H) is added to the perovskite compound represented by the general formula (1a). - A method for producing a hydrogen-containing perovskite compound, comprising obtaining a hydrogen-containing perovskite compound having ) and a molar ratio of hydride ion content n to w (n / w) of 2 or less. [ka] (In the formula, M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca.) x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is a value such that the average value of In is between +1.0 and +2.5. y ≥ w. [P7] The above hydrogen-containing perovskite compound is represented by the following general formula (2a), and the method of production is as described in [P6]. [ka] (In formula (2a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca.) H is a hydride ion, x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is the value at which the average value of In is greater than +1.0 and less than or equal to +3.0. y ≥ w, and n / w ≤ 2. [P8] The manufacturing method according to [P7], wherein In in formula (2a) is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valency of +3. [P9] The hydrogen-containing perovskite compound represented by general formula (2a) is represented by the following general formula (2b), and the method of production described in [P8]. [ka] [P10] The hydrogen-containing perovskite compound represented by general formula (2a) contains In(II) and is represented by the following general formula (2c) or general formula (2d), as described in the manufacturing method described in [P8]. [ka] [P11] The method for producing a perovskite compound represented by general formulas (1a) to (1d) is a compound in which a portion of the B-site element is substituted with at least one element selected from the group consisting of rare earth elements, Ni, and Zn, as described in any one of [P1] to [P10]. [P12] The hydrogen-containing perovskite compound represented by general formulas (2a) to (2d) is a compound in which a portion of the B-site element is substituted with at least one element selected from the group consisting of rare earth elements and Ni and Zn, according to the method for producing it according to any one of [P7] to [P10]. [Effects of the Invention]

[0012] According to the present invention, a material with excellent hydrogen permeability can be provided even in a temperature range of 600°C or less and in a water vapor-containing atmosphere. Furthermore, by using the hydrogen permeable material of the present invention, a fuel cell that operates in a temperature range of 600°C or less and in a water vapor-containing atmosphere can be provided. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 shows the powder X-ray diffraction (XRD) pattern of the sample. [Figure 2] Figure 2 shows the XRD pattern of the sample. [Figure 3] Figure 3 is a graph showing the relationship between temperature and electrical conductivity in the sample. [Figure 4] Figure 4 shows the thermogravimetric curve of the sample. [Figure 5] Figure 5 shows the In-K edge X-ray absorption fine structure (XAFS) spectrum of the sample. [Figure 6] Figure 6 shows the nuclear magnetic resonance (NMR) measurement data of the sample. [Figure 7] Figure 7 shows the secondary ion mass spectrometry (SIMS) profile of the sample. [Figure 8] Figure 8 shows the neutron diffraction (NRD) pattern and Rietveld calculation profile of the sample. [Figure 9A] Figure 9A is a conceptual diagram showing the positions of hydrogen atoms in a perovskite-type BZI compound. [Figure 9B] Figure 9B shows the electron spin resonance (ESR) spectrum of the sample. [Figure 10] Figure 10 is a conceptual diagram showing a hydrogen permeability measurement system. [Figure 11] Figure 11 shows the measurement data for the hydrogen permeation rate of the sample. [Figure 12] Figure 12(a) is a conceptual diagram of the thin-film device fabricated in the example. Figures 12(b) to (e) are scanning electron microscope (SEM) images of a cross-section of the thin-film device shown in Figure 12(a). [Figure 13]Figure 13 is a graph showing the relationship between temperature and hydrogen permeability of the thin-film device shown in Figure 12. [Figure 14] Figure 14(a) is a conceptual diagram of the fuel cell fabricated in the example. Figures 14(b) to (d) are cross-sectional SEM images of the fuel cell. [Figure 15] Figure 15 shows the output characteristics (current-voltage-output curve) of the fuel cell. [Modes for carrying out the invention]

[0014] The perovskite-type compounds contained in the hydrogen permeable material of the present invention are perovskite-type compounds represented by the following general formulas (1a) to (1d), and perovskite-type compounds represented by the general formulas (1a) to (1d) containing hydride ions (H - These are hydrogen-containing perovskite-type compounds containing ) or hydrates thereof or mixtures thereof.

[0015] <Perovskite-type compounds> The perovskite-type compounds that may be included in the hydrogen permeable material of the present invention are represented by the following general formula (1a). [ka]

[0016] In general formula (1a), M is the element at the A site of the perovskite-type structure, and is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca. From the viewpoint of providing a hydrogen-containing perovskite-type compound having desired hydrogen permeability, M is preferably Ba, or at least a part of it is Ba. When M is Ba, Sr, Ca, or both, Ba:(Sr+Ca) is preferably in the range of 1:0.1 to 1. x represents the deletion rate from the stoichiometric ratio of the alkaline earth metal M, and is a value between 0 and 0.3. From the viewpoint of providing a hydrogen-containing perovskite-type compound having desired hydrogen permeability, x is preferably a value between 0.05 and 0.25, and more preferably a value between 0.07 and 0.23.

[0017] In general formula (1a), the elements at the B site of the perovskite structure are Zr and In. In can exist in the valence states of In(I), In(II), or In(III). In(I) is In with a valence of +1, In(II) is In with a valence of +2, and In(III) is In with a valence of +3. In other words, when ionized, In can have valencies of +1, +2, or +3, with +3 being the more stable valence. w is the value such that the average valence of In is between +1.0 and +2.5. When the total amount of In is In(I), the average valence is +1.0, and (1 × w + 3 × (yw)) / y = 1.0, so w = y. Also, when the average valence of In is +2.5, w = y / 4. This is because, in typical perovskite compounds, all In is In(III) and has an average valency of +3.0, but as the average valency decreases from +3.0 to +2.5, an amount of oxygen (valency -2.0) corresponding to the decrease of 0.5 is lost to balance the charge. Alternatively, assuming that In is In(I) and In(III), and based on the composition ratio of general formula (1b) described later, it is also possible to derive w=y / 4 from the equation (1×w+3×(yw)) / y=2.5 regarding the average valency. As the average valency of In in the perovskite compound approaches +1, the capacity that can introduce hydride ions increases. From the viewpoint of providing a hydrogen-containing perovskite compound with excellent hydrogen permeability, the ratio of w to y (w / y) in general formula (1a) is preferably 0.30~0.97, more preferably 0.35~0.95, and even more preferably 0.40~0.93. From the viewpoint of providing a hydrogen-containing perovskite-type compound with excellent hydrogen permeability, the average valency of In in the perovskite-type compound represented by general formula (1a) is preferably +1.05 or more and +2.30 or less, more preferably +1.10 or more and +2.10 or less, and even more preferably +1.15 or more and +2.00 or less.

[0018] The average valency of In can be determined from the perspective of the overall charge balance of the composition by the following formula.

number

[0019] In equation D, the symbol Σ indicates that if there are multiple A-site atoms in the perovskite structure, the sum is taken over those atoms, and if there are multiple B-site atoms excluding In, the sum is taken over those atoms. The valence of the A-site atoms and the valence of the B-site atoms excluding In can be determined once the atoms are identified. For example, if the A-site atom is Ba, the valence is +2, and if the B-site atom is Zr, the valence is +4. The valence of oxygen is -2. The proportions of A-site atoms, B-site atoms, and oxygen can be determined by elemental analysis of the perovskite compound using conventional methods or by SIMS analysis as shown in the examples. The proportion of oxygen can also be determined from the mass change obtained by thermogravimetric analysis of the perovskite compound in a hydrogen atmosphere.

[0020] The total amount of In, y, including In(I), In(II), and In(III), is greater than 0 and less than or equal to 0.75. If y is 0.75 or less, a perovskite-type structure can be formed. However, hydride ions (H) - Since hydrogen-containing perovskite compounds containing ) are expected to be used under heating, it is preferable that y be 0.55 or less, considering excellent structural stability under heating. On the other hand, hydride ions (H - From the viewpoint of providing a hydrogen-containing perovskite-type compound containing ), y is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.3 or more, and even more preferably 0.4 or more, provided that y ≥ w.

[0021] In formula (1a), In can be In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). In particular, In in formula (1a) can be In(I) and In(II), In(II) and In(III), or In(I) and In(III). Results from ESR measurements described later have confirmed that in the perovskite compound represented by general formula (1a), In is in the state of In(I) and In(III) at around 77K, and In contains In(II) at room temperature (298K) and above.

[0022] When In is in the form of In(I) and In(III), the perovskite compound represented by general formula (1a) is represented by the following general formula (1b). If the total amount of In is y, then the amount of In(I) is represented by w, and the amount of In(III) is represented by yw. [ka]

[0023] Furthermore, the perovskite compound represented by general formula (1a) may contain In(II) and may also be a compound represented by general formula (1c) or general formula (1d) below. [ka]

[0024] Compounds represented by general formulas (1c) and (1d) can also be considered as the perovskite-type compound represented by general formula (1b) with the charge averaged between In(I) and In(III). In other words, the compound represented by general formula (1c) can be considered as the compound represented by general formula (1b) where, if the amount of In(I) is less than the amount of In(III) (y > 2w), the charge averages between In(I) and In(III), resulting in the formation of In(II). Similarly, the compound represented by general formula (1d) can be considered as the compound represented by general formula (1b) where, if the amount of In(I) is greater than or equal to the amount of In(III) (y ≤ 2w), the charge averages between In(I) and In(III), resulting in the formation of In(II). Thus, the compound represented by general formula (1b) and the compound represented by general formulas (1c) or (1d) are equivalent compounds with the same composition, differing only in the valence state of In.

[0025] In perovskite-type compounds represented by general formulas (1a) to (1d), a portion of the B-site elements, Zr and In, may be substituted with at least one element selected from the group consisting of rare earth elements, Ni, and Zn. The content of these elements is within a range that does not impair the structure and hydrogen permeability of the perovskite-type compound in the hydrogen permeable material of the present invention, and can be, for example, 0.05 moles or less, preferably 0.02 moles or less. The rare earth elements are specifically Sc and Y, and elements belonging to the lanthanides: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. By substituting a portion of the B-site elements with Ni and Zn, the strength of the sintered body of the perovskite-type compound can be increased. Furthermore, the substitution of some of the B-site elements with rare earth elements is expected to broaden the stable temperature and hydrogen partial pressure range of the in-containing perovskite phase, which has a low average valence due to the presence of in(I), etc.

[0026] The quantitative determination of the content of metal elements (M, Zr, In, rare earth elements, Ni, and Zn) in perovskite compounds represented by general formula (1a), etc., hydrogen-containing perovskite compounds represented by general formula (2a), etc., and their hydrates can be performed by conventional methods for elemental analysis of metal elements, such as atomic absorption spectrometry or titration, or by SIMS measurement, based on comparison with the SIMS profile of a standard sample.

[0027] <Hydrogen-containing perovskite-type compounds> The hydrogen-containing perovskite-type compounds that may be included in the hydrogen-permeable material of the present invention are perovskite-type compounds represented by general formulas (1a) to (1d) containing a hydride ion (H - This is a compound that contains ) and has a molar ratio of hydride ion content n to w (n / w) of 2 or less. Furthermore, w is a value such that the average valency of In is greater than +1.0 and less than or equal to +3.0.

[0028] Hydrogen-containing perovskite compounds can also be represented by the following general formula (2a). [ka] In formula (2a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca. H is a hydride ion, x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.75. w is the value at which the average value of In is greater than +1.0 and less than or equal to +3.0. y ≥ w and n / w ≤ 2.

[0029] For example, as can be seen from a comparison of general formulas (1a) and (2a), the amount of oxygen deficiency does not usually change even when hydride ions are introduced into a compound. From the viewpoint of providing a hydrogen-containing perovskite compound with excellent hydrogen permeability, the ratio of w to y (w / y) in general formula (2a) is 0.25 to 1, preferably 0.30 to 0.97, more preferably 0.35 to 0.95, and even more preferably 0.40 to 0.93. From the viewpoint of providing a hydrogen-containing perovskite compound with excellent hydrogen permeability, the average valence of In in the hydrogen-containing perovskite compound is preferably +1.1 or more and +2.9 or less, more preferably +1.2 or more and +2.8 or less, and even more preferably +1.3 or more and +2.7 or less. From the viewpoint of the charge balance of the entire composition, the average valence of In in the hydrogen-containing perovskite compound can be determined by the following formula.

number

[0030] Equation D' is [+(+1)×H + The ratio + (-1) × H - This is the same as equation D except that the term "[proportion of]" has been added. ``(+1)×H + The term "(-1) × H" indicates that the effect of the charge of a +1 valence hydrogen ion is taken into account when one is present, and is expressed as "(-1) × H - The term "proportion of" indicates that the effect of the charge of a -1 valent hydride ion is taken into account when one is present. + As will be discussed later, the proportion of H is practically negligible. - The proportion can be determined from the measurement results of SIMS and NRD.

[0031] In general formula (2a), H represents hydrogen, which is a hydride ion, and n indicates the hydride ion content ratio. As can be seen from formulas (1a) and (2a), hydride ions (H - ) and hydride ions (H) such that the charge difference between In(III) and In(I) is balanced. - ) exists. Hydride ions (H- As the amount increases, the amount of In(I) or In(II) decreases and the amount of In(II) or In(III) increases, so that the average valency increases. In this way, hydride ions (H - The negative charge of the hydride ion (H) in hydrogen-containing perovskite compounds is offset by the positive charge resulting from an increase in the average valence due to an increase in the amount of In(III), thus balancing the charge. - The upper limit of the content of ) is determined by the amount of In(I) w and the average valence of In, and the molar ratio (n / w) is 2 or less (n / w ≤ 2). The minimum value of w - 0.5n is 0 (zero).

[0032] In formula (2a) can be In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). In formula (2a) can be, in particular, In(I) and In(II), In(II) and In(III), or In(I) and In(III).

[0033] When In is In(I) and In(III), the hydrogen-containing perovskite compound represented by general formula (2a) is represented by the following general formula (2b). [ka]

[0034] The molar ratio (n / (w-0.5n)) of hydride ions to In(I) in general formula (2b) is preferably in the range of 0.01 to 20, and more preferably in the range of 0.1 to 10.

[0035] Furthermore, in the hydrogen-containing perovskite compound represented by general formula (2b), the charge may be averaged between In(I) and In(III), resulting in the formation of In(II). In other words, the hydrogen-containing perovskite compound represented by general formula (2a) may contain In(II) and may be a compound represented by general formula (2c) or general formula (2d) below. [ka]

[0036] The compound represented by general formula (2c) can be considered as the compound represented by general formula (2b) in which, when the amount of In(I) is less than the amount of In(III) (y > 2w), the charge is averaged between In(I) and In(III), resulting in the formation of In(II). Similarly, the compound represented by general formula (2d) can be considered as the compound represented by general formula (2b) in which, when the amount of In(I) is greater than or equal to the amount of In(III) (y ≤ 2w), the charge is averaged between In(I) and In(III), resulting in the formation of In(II). Thus, the compound represented by general formula (2b) and the compounds represented by general formula (2c) or (2d) are equivalent compounds with the same composition, differing only in the valence state of In.

[0037] In hydrogen-containing perovskite compounds, hydride ions are present in interstitial positions near the (100), (001), and (010) face centers of the perovskite structure, as well as in at least some of the oxygen vacancy positions. Figure 9A shows a schematic diagram of one embodiment of a hydrogen-containing perovskite compound. (a) H i This is a proton located near the lattice oxygen, as shown in (b) H fcc These are hydrogen atoms located in interstitial positions near the center of the (100), (001), and (010) faces, as shown in (c) H O This is a hydrogen atom located at an oxygen vacancy. However, in hydrogen-containing perovskite compounds, the amount of protons near lattice oxygen atoms is negligible.

[0038] As shown in Table 6, composition BaZr 0.5 In 0.5 O 2.53 H 0.16 Most of the deuterium in sample 23d (corresponding to the compound represented by general formula (2a) with x=0, y=0.5, w=0.22 and n=0.16) is D fcc D OThe proportion of is very small. In contrast, as shown in Table 7, composition Ba 0.8 Zr 0.5 In 0.5 O 2.28 H 0.21 In the case of sample 27d (corresponding to the compound represented by x=0.2, y=0.5, w=0.27 and n=0.21 in general formula (2a)), D O The amount is D fcc It is about the same amount as . From this, by deleting Ba (x>0), D O The proportion of will increase.

[0039] The hydride ion content of hydrogen-containing perovskite compounds is determined by secondary ion mass spectrometry or neutron diffraction. For secondary ion mass spectrometry, see the description in Examples 2-2. For neutron diffraction measurement, see the description in Examples 2-3.

[0040] In hydrogen-containing perovskite compounds, a portion of the B-site elements, Zr and In, may be substituted with at least one element selected from the group consisting of rare earth elements, Ni, and Zn. The content of these elements is kept within a range that does not impair the structure and hydrogen permeability of the hydrogen-containing perovskite compound, for example, 0.05 moles or less, preferably 0.02 moles or less. Specifically, the rare earth elements are Sc and Y, as well as elements belonging to the lanthanides: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. By substituting a portion of the B-site elements with Ni and Zn, the strength of the sintered body of the perovskite compound can be increased. Furthermore, by substituting a portion of the B-site elements with rare earth elements, it is expected that the stable temperature and hydrogen partial pressure range of the perovskite phase will be broadened.

[0041] <Hydrates of perovskite-type compounds> The hydrogen permeation material of the present invention can be a material containing a hydrate of the perovskite-type compound or a hydrate of the hydrogen-containing perovskite-type compound. These hydrates can be hydrates represented by any one of the following general formulas (3a) to (3d) or any one of the following general formulas (4a) to (4d). [Chemical formula] (Formula (3a) represents a hydrate of the compound represented by formula (1a). M, x, y, and w in formula (3a) have the same meanings as those in formula (1a). Formula (3b) represents a hydrate of the compound represented by formula (1b). M, In(I), In(III), x, y, and w in formula (3b) have the same meanings as those in formula (1b). Formula (3c) represents a hydrate of the compound represented by formula (1c). M, In(II), In(III), x, y, and w in formula (3c) have the same meanings as those in formula (1c). Formula (3d) represents a hydrate of the compound represented by formula (1d). M, In(I), In(II), x, y, and w in formula (3d) have the same meanings as those in formula (1d). Formula (4a) represents a hydrate of the compound represented by formula (2a). M, H with n attached, x, y, w, and n in formula (4a) have the same meanings as those in formula (2a). Formula (4b) represents a hydrate of the compound represented by formula (2b). M, In(I), In(III), H with n attached, x, y, w, and n in formula (4b) have the same meanings as those in formula (2b). Formula (4c) represents a hydrate of the compound represented by formula (2c). M, In(II), In(III), H with n attached, x, y, w, and n in formula (4c) have the same meanings as those in formula (2c). Formula (4d) represents a hydrate of the compound represented by formula (2d). M, In(I), In(II), H with n attached, x, y, w, and n in formula (4d) have the same meanings as those in formula (2d). l is a positive number satisfying l < x + 0.5y + w.)

[0042] Hydrates of perovskite-type compounds and hydrogen-containing perovskite-type compounds are obtained by exposing the perovskite-type compound and the hydrogen-containing perovskite-type compound, respectively, to a water vapor-containing atmosphere. Therefore, by using composite materials or fuel cells using the perovskite-type compound or hydrogen-containing perovskite-type compound described later in a water vapor-containing atmosphere or a water vapor and hydrogen-containing atmosphere, at least a portion of the perovskite-type compound or hydrogen-containing perovskite-type compound will be converted into hydrates.

[0043] <Hydrogen permeable materials> The hydrogen permeable material of the present invention is a hydrogen permeable material containing a perovskite-type compound, a hydrogen-containing perovskite-type compound, and / or hydrates thereof. The hydrogen permeable material of the present invention may consist only of a perovskite-type compound, a hydrogen-containing perovskite-type compound, and / or hydrates thereof, or it may be a composition containing additives in addition to these. The additives may be oxides or nitrates of Ni, Zn, Co, and Cu, for example, as sintering aids. When a perovskite-type compound is sintered using nickel oxide (NiO) or zinc oxide (ZnO) as a sintering aid, Ni or Zn replaces part of the Zr or In at the B site during sintering, resulting in a perovskite-type compound containing Ni or Zn at the B site of the perovskite-type structure.

[0044] <Method for producing perovskite-type compounds> Perovskite compounds represented by general formulas (1a) to (1d) can be obtained by heating the perovskite compound represented by general formula (5a) and / or its hydrate (hereinafter sometimes referred to as the starting compound) in a hydrogen atmosphere at 600°C or higher. The perovskite compound represented by general formula (5a) is a typical ZrIn-containing perovskite compound. Considering that In usually takes on a +3 valency state, the perovskite compound represented by general formula (5a) can also be said to be represented by general formula (5b). [ka] In equations (5a) and (5b), M, x, and y are equivalent to those in equation (1a).

[0045] The raw material compounds can be prepared by conventional methods from, for example, metal salts such as carbonates and nitrates, and / or metal oxides (see, for example, References 1 and 3).

[0046] The raw material compound is heated to 600°C or higher in a hydrogen atmosphere. The hydrogen atmosphere can be 100% hydrogen gas or a mixed gas of hydrogen gas and an inert gas such as argon. In the case of a mixed gas, the hydrogen gas content is, for example, 1% or more, preferably 5% or more, and more preferably 10% or more. From the viewpoint of providing a hydrogen-containing perovskite-type compound with excellent hydrogen permeability, it is preferable that the hydrogen atmosphere be 100% hydrogen gas. It is preferable that the hydrogen atmosphere does not contain water. This is because if the hydrogen atmosphere contains water, the reduction of the average valence of In, such as the generation of In(I) by the reduction of In(III), tends to be hindered. The heating temperature is in the range of 600 to 900°C, preferably 630 to 870°C, and more preferably 650 to 850°C. The heating time can be appropriately determined according to the heating temperature and the desired w, and can be, for example, in the range of 0.1 to 50 hours, preferably 1 to 40 hours, and more preferably 1.5 to 35 hours. However, it is not intended to be limited to this range.

[0047] <Method for producing hydrogen-containing perovskite-type compounds> The hydrogen-containing perovskite compounds represented by general formulas (2a) to (2d) are each obtained by exposing the perovskite compounds represented by general formulas (1a) to (1d) to a hydrogen atmosphere at a temperature above room temperature and below 600°C, and adding hydride ions (H) to the perovskite compounds represented by general formulas (1a) to (1d). - This can be prepared by introducing the following:

[0048] The hydrogen atmosphere can be 100% hydrogen gas or a mixed gas of hydrogen gas and an inert gas such as argon. In the case of a mixed gas, the hydrogen gas content is, for example, 1% or more, preferably 5% or more, and more preferably 10% or more. From the viewpoint of providing a hydrogen-containing perovskite compound with excellent hydrogen permeability, it is preferable that the hydrogen atmosphere be 100% hydrogen gas. It is preferable that the hydrogen atmosphere does not contain water, from the viewpoint of promoting hydrogen introduction.

[0049] The exposure temperature to the hydrogen atmosphere is in the range of room temperature or higher and less than 600°C, and can be appropriately determined considering the amount of hydride ions introduced and the time required for introduction. From the viewpoint of shortening the hydride ion introduction time, the exposure temperature to the hydrogen atmosphere is preferably 100°C or higher, and more preferably 200°C or higher. On the other hand, the amount of hydride ions introduced, i.e., the amount of substitution with In(I) and In(II), tends to increase as the exposure temperature to the hydrogen atmosphere decreases to a certain extent. Considering this point, the exposure temperature to the hydrogen atmosphere is 500°C or lower, preferably 400°C or lower. However, exposure to the hydrogen atmosphere does not need to be performed at a constant temperature; exposure to the hydrogen atmosphere at a temperature in the range of room temperature or higher and less than 600°C is sufficient. Exposure to the hydrogen atmosphere can also be performed by, for example, continuously or intermittently lowering the temperature from 600°C at a predetermined rate within the hydrogen atmosphere. The exposure time to a hydrogen atmosphere can be appropriately determined considering the composition of the perovskite compound before exposure (especially the amounts of In(I) and In(II)), the desired amount of hydride ions, the hydrogen gas concentration of the hydrogen atmosphere, the temperature, etc., but for example, it can be in the range of 0.1 to 24 hours, preferably in the range of 0.5 to 12 hours. However, it is not intended to be limited to this range.

[0050] In a temperature range of room temperature or higher and below 600°C, exposure of perovskite compounds represented by general formulas (1a) to (1d) to a hydrogen atmosphere causes hydrogen gas in the atmosphere to be incorporated into the perovskite compound and reduced by In(I) or In(II) to form hydride ions. Along with the introduction of hydride ions, In(I) is oxidized to In(II) or In(III), and In(II) is oxidized to In(III). Hydrogen-containing perovskite compounds can be represented by general formulas (2a) to (2d), and the molar ratio (n / w) of the hydride ion content n to w is 2 or less. In general formulas (2a) to (2d), H represents a hydride ion, and n represents the hydride ion content. For general formulas (1a) to (1d), the introduction of n amounts of hydride ions causes charge transfer between In(I), In(II), and In(III) such that the average valence of In increases, and the respective contents of In(I), In(II), and In(III) change. For example, if In is In(I) and In(III), as shown in general formulas (1b) and (2b), the introduction of n amounts of hydride ions causes a decrease of 0.5n of In(I) and an increase of 0.5n of In(III). [ka]

[0051] Based on the TG and XAFS measurement results shown in the examples, Ba 1-x Zr 1-y In y O 3-x-0.5y The compound shown is formed when In is reduced in hydrogen gas at a temperature of 600°C or higher. Ba 1-x Zr 1-y In(I) w In(III) y-w O 3-x-0.5y-w The In-reduced compound represented by formula (1b), M 1-x Zr 1-y In(II) 2w In(III) y-2w O 3-x-0.5y-w In-reduced compounds represented by (formula (1c)), and M1-x Zr 1-y In(I) 2w-y In(II) 2y-2w O 3-x-0.5y-w In-reduced compounds represented by (formula (1d)), M 1-x Zr 1-y In y O 3-x-0.5y-w It is thought to transform into an In-reduced compound represented by (formula (1a)).

[0052] For example, if In is In(I) and In(III), the reaction is thought to follow reaction equation A1 below. Similarly, if In is In(II) and In(III) or In(I) and In(II), the reaction is thought to follow reaction equations A2 or A3 below, respectively. [ka]

[0053] In contrast, when reduced In compounds are exposed to a hydrogen atmosphere at temperatures below 600°C, it is thought that hydride ions are introduced and In(I) and other In components are oxidized, transforming them into hydrogen-containing compounds represented by general formula (2a). For example, when In is In(I) and In(III), the reduced In compound obtained by reaction formula A1 is thought to undergo hydride ion introduction and In(I) oxidation according to reaction formula B when exposed to a hydrogen atmosphere at temperatures below 600°C, transforming it into hydrogen-containing compounds represented by general formula (2b) according to reaction formula C1. Similarly, when In is In(II) and In(III) or In(I) and In(II), it is thought that the reaction follows reaction formula C2 or C3 below, respectively. [ka]

[0054] In reaction equation B, the superscripts "'" and "×" indicate relative charges of -1 and zero, respectively. i This is a hydrogen impurity, In(I) Inand In(III) In These represent +1-valent and +3-valent In at the In lattice sites, respectively.

[0055] Molded bodies of hydrogen-containing perovskite-type compounds into which hydride ions have been introduced, such as a film-like body as a single entity or a composite in which a film-like body is provided on a support, are prepared by first preparing a perovskite-type compound represented by general formulas (1a) to (1d) as a film-like body as a single entity or a composite in which a film-like body is provided on a support, and then, in the same manner as above, exposing it to a hydrogen atmosphere at a temperature of less than 600°C to introduce hydride ions (H) into the perovskite-type compound represented by general formula (1), which is a film-like body. - This can be prepared by introducing the following:

[0056] <Composite material having a hydrogen permeable layer> The present invention includes a composite member having a hydrogen permeable layer made of the hydrogen permeable material of the present invention on at least a portion of the surface of a porous substrate. There are no particular restrictions on the porous substrate, but it can be any material that is resistant in the environment in which the composite member having the hydrogen permeable layer is used, and the degree of porosity can be appropriately determined according to the application of the composite member having the hydrogen permeable layer. The porous substrate can be, for example, a porous cermet substrate, and it is preferable that the ceramic component is a perovskite-type compound represented by general formulas (1a) to (1d) or (2a) to (2d) which is substantially the same as the perovskite-type compound constituting the hydrogen permeable layer, from the viewpoint of avoiding contamination of the hydrogen permeable layer during the preparation of the composite member. There are no particular restrictions on the metal component, but examples include nickel and zinc.

[0057] A porous cermet substrate can be made by forming a mixture of particulate nickel oxide or zinc oxide and granular perovskite-type compounds represented by general formula (5a) or (5b), and then subjecting this mixture to a reduction treatment, thereby producing a porous cermet substrate composed of nickel or zinc and a perovskite-type compound represented by general formula (1). [ka]

[0058] A paste layer of a perovskite-type compound represented by general formula (5a) or (5b) is formed on this porous cermet substrate and fired to obtain a precursor of a composite having a perovskite-type compound layer represented by general formula (5a) or (5b) on the porous cermet substrate. This precursor is heated at 600°C or higher in a hydrogen atmosphere in the same manner as the method for producing perovskite-type compounds represented by general formulas (1a) to (1d) to convert the perovskite-type compounds in the porous cermet substrate and the perovskite-type compound layer into perovskite-type compounds represented by general formulas (1a) to (1d). Then, it is exposed to a hydrogen atmosphere at a temperature of less than 600°C to convert the perovskite-type compounds represented by general formulas (1a) to (1d) in the porous cermet substrate and the perovskite-type compound layer into hydride ions (H - By introducing a process, the perovskite compounds in the porous cermet substrate and perovskite compound layer are converted into hydrogen-containing perovskite compounds.

[0059] Hydrogen-permeable materials containing hydrogen-containing perovskite compounds can conduct electrons and hydrogen simultaneously, thereby enabling hydrogen transport within the material. This hydrogen transport is thought to be due to hydride ions contained in the hydrogen-containing perovskite compounds. The ability of hydrogen-permeable materials containing hydrogen-containing perovskite compounds to conduct electrons and hydrogen simultaneously is shown in the results of Figure 11(b).

[0060] Hydrogen-permeable materials containing hydrates of hydrogen-containing perovskite compounds can conduct electrons and hydride ions simultaneously, thereby enabling hydrogen transport within the material. It is also believed that protons generated by hydration may contribute to hydrogen transport.

[0061] Hydrogen-permeable materials containing hydrates of perovskite-type compounds can conduct electrons and protons simultaneously, thereby enabling hydrogen transport within the material. This hydrogen transport is thought to be due to the protons contained in the hydrates. The ability of hydrogen-permeable materials containing hydrates to conduct electrons and hydrogen simultaneously is shown in the results of Figure 11(a).

[0062] <Fuel cell> The present invention includes a fuel cell having an anode layer, an electrolyte layer, and a cathode layer made of the hydrogen permeable material of the present invention, in that order, on at least a portion of one main surface of a porous substrate. The fuel cell of the present invention is a proton ceramic fuel cell (hereinafter sometimes abbreviated as PCFC) in which the anode layer is made of the hydrogen permeable material of the present invention and the electrolyte is made of a proton conductive ceramic (solid). The electrolyte layer of the PCFC of the present invention is a proton conductor, BaZr x Ce 1-x-z Y z The electrolyte can be O3 (x=0.1~0.8, z=0.1~0.25, x+z≦1.0) (hereinafter sometimes abbreviated as BZCY). BZCY is a well-known electrolyte for PCFCs, and there are no particular limitations as long as it satisfies the above composition formula. x+z is preferably in the range of <0.8.

[0063] The cathode in the fuel cell of the present invention has the function of adsorbing oxygen molecules, dissociating them, and ionizing them. In the cathode, protons conducted through the electrolyte and oxygen ions (O 2- A reaction (oxygen reduction reaction) occurs with ions. There are no particular restrictions on the cathode material, but known materials used as cathodes in fuel cells can be used. Examples of cathode materials include metal oxides having a perovskite crystal structure, specifically samarium strontium cobaltite, for example, Sm 0.5 Sr 0.5 CoO3, lanthanum strontium cobalt ferrite, for example, La 1-x Sr x Fe 1-y Co yO3 (0 < x < 1, 0.1 ≦ y ≦ 1), barium strontium cobalt ferrite, for example, Ba 0.5 Sr 0.5 Co 0.6 Fe 0.4 O3, praseodymium nickel oxide, for example, Pr2NiO4, etc. can be mentioned. However, it is not intended to be limited to these. There is no particular limitation on the film thickness of the cathode, but for example, it can be in the range of 1 to 1000 μm. However, it is not intended to be limited to this range.

[0064] The PCFC of the present invention can have an operating temperature, for example, in the range of 400 to 600 °C, a preferred operating temperature is 450 °C or higher, a more preferred operating temperature is 500 °C or higher, and even more preferably 550 °C or higher.

[0065] [Manufacturing method of PCFC] The PCFC of the present invention can be manufactured, for example, by forming an electrolyte layer and a cathode layer in this order on a hydrogen-permeable layer of a composite member having a hydrogen-permeable layer made of the hydrogen-permeable material of the present invention on at least a part of one main surface of a porous substrate.

Examples

[0066] Hereinafter, the present invention will be described more specifically with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[0067] Hereinafter, a normal perovskite-type compound containing Ba, In, and Zr may be described as a "BZI compound". Further, a perovskite-type compound containing reduced In (that is, In(I) and In(II)) may be particularly referred to as an "In-reduced BZI compound", and a perovskite-type compound containing hydrogen as a hydride ion may be particularly referred to as a "hydrogen-containing BZI compound".

[0068] Example 1 1-1. Preparation of BZI compound According to the stoichiometric composition ratios shown in Table 1, each BZI compound was prepared by the following method. First, a sample was prepared by mixing BaCO3, In2O3, and ZrO2 using a ball mill so that Ba, In, and Zr satisfied the desired molar ratios, and this sample was heated at 900°C for 6 hours. Next, the sample was pulverized using a ball mill and further heated at 1300°C for 8 hours. The sample was pulverized again using a ball mill, and then molded using a uniaxial press and a hydrostatic press. The molded body was heated at 1500°C for 8 hours to obtain a dense sintered body of the BZI compound. In addition, the dense sintered body prepared in the same manner as above was pulverized in a mortar to obtain powder of the BZI compound. Below, for each composition example, the sample prepared according to this process is described with a sample number as shown in Table 2, depending on the type of sintered body and powder.

[0069] [Table 1] [Table 2]

[0070] 1-2. Preparation of In-reduced BZI compounds The In-reduced BZI compounds in this example were obtained by heating the sample prepared according to 1-1 above at 700-800°C for 5 hours or more in dry hydrogen gas. The dew point temperature for the water vapor partial pressure of the dry gas was -78°C or lower, and the same applies to subsequent examples. The preparation conditions for the In-reduced BZI compounds differ for each measurement described later, so the details of the preparation conditions will be explained in the section for each measurement.

[0071] 1-3. Preparation of hydrogen-containing BZI compounds The hydrogen-containing BZI compounds in this example were obtained by heating a sample prepared according to 1-1 above at 700-800°C for 5 hours or more in dry hydrogen gas, and then exposing it to dry hydrogen gas at a temperature below 600°C for a predetermined time. The preparation conditions for the hydrogen-containing BZI compounds differ for each measurement described later, so the details of the preparation conditions will be explained in the section for each measurement. In this example, the process of heating a sample at a high temperature in dry hydrogen gas (or deuterium gas) for a predetermined time, and then leaving it in a relatively low temperature range in dry hydrogen gas (or deuterium gas) for a predetermined time or more, is also referred to as "hydrogen introduction treatment".

[0072] 1-4.XRD measurement Powder X-ray diffraction (XRD) measurements were performed on powder samples 11b to 18b prepared in 1-1 above. Powder XRD measurements were performed using a RIGAKU ULTIMA4 diffractometer with a 2θ / θ scan rate of 10 degrees / min. Figure 1 shows the XRD patterns of samples 11b to 15b. Figure 2 shows the XRD patterns of samples 13b, 16b to 18b. Figure 2 also shows the XRD patterns of samples 13b, 16b, and 17b after the hydrogen introduction treatment described later. In Figure 2, the solid lines show the XRD patterns of the samples as prepared in 1-1 above (before hydrogen introduction treatment), and the dashed lines show the XRD patterns of the samples after hydrogen introduction treatment.

[0073] From these XRD patterns, it was determined that samples 11b to 17b (x=0 to 0.2 and y=0.3 to 0.7) were all cubic perovskite phases. All of these samples were milky white solids. On the other hand, when the Ba defect was increased up to sample 18b (x=0.3), an In2O3 impurity phase was formed under the preparation conditions for sample 18b, and a single phase could not be obtained. However, a single phase can be obtained by optimizing the conditions. Although not shown in the figure, sample 19b (x=0.1 and y=0.3) was also found to be a cubic perovskite phase from its XRD pattern.

[0074] 1-5. Measurement of Electrical Conductivity The electrical conductivity of the sintered body samples 11a to 17a obtained in 1-1 above was evaluated. After polishing both sides of each sample (10 mm in diameter, 1.2 mm in thickness) with SiC paper, Pt paste was baked onto both sides to create electrodes. Using these electrodes, electrical conductivity measurements were performed using the AC two-terminal method. First, the above sintered body samples were heated to 800°C in humidified Ar gas, and the electrical conductivity was measured in increments of 50°C or 100°C while cooling at a rate of 10°C / min in the range from 800°C to 100°C. The water vapor partial pressure (p) in the humidified gas was used. H2O The atmospheric pressure was approximately 0.023 atm, and the same was true in subsequent examples. Next, the temperature was raised to 800°C while maintaining the same atmosphere, and then the atmosphere was switched to dry hydrogen gas, and the mixture was heated at 800°C for 30 hours. The method for identifying the compounds will be explained in detail later, but at this time, the In in the sample is reduced from +3 to +1, and the BZI compound changes into an In-reduced BZI compound (a compound represented by general formula (1)). After the above 30 hours of heating, the electrical conductivity was measured in 50°C or 100°C increments while cooling at 10°C / min in the range from 800°C to 100°C while maintaining the same atmosphere.

[0075] Figure 3 is a graph showing the relationship between temperature and electrical conductivity for each sample. In Figure 3, (a) sample 11a (x=0 and y=0.3), (b) sample 12a (x=0 and y=0.4), (c) sample 14a (x=0 and y=0.6), (d) sample 15a (x=0 and y=0.7), (e) sample 13a (x=0 and y=0.5), (f) sample 16a (x=0.1 and y=0.5), and (g) sample 17a (x=0.2 and y=0.5). The measurement results are shown in Arrhenius plot format. The images shown in each graph are photographs of the samples before and after heating in a dry hydrogen gas atmosphere. After measurement in a dry hydrogen gas atmosphere, all samples changed from milky white to black. Figures 3(e) to (g) also show the measurement results for samples that underwent hydrogen introduction treatment, which will be described later.

[0076] First, according to past reports, generally, in environments containing water vapor, BZI compounds incorporate water molecules as hydroxyl groups (OH) through a hydration reaction represented by the following reaction equation E, forming the hydrate Ba1-x Zr 1-y In y O 3-x-0.5y-k (OH) 2k (k ≤ x + 0.5y) varies to (see References 1 and 2. For references, see the reference list below.).

Chemical Formula

[0077] Reaction formula E represents a hydration reaction by the association of water molecules (H2O) and lattice oxygen defects (V O ·· ). Here, the capital element symbols represent each element, "OH" represents a hydroxyl group formed by the bonding of lattice oxygen and a proton, and the subscript element symbols represent the lattice sites of each atom in the perovskite crystal structure. Also, the superscript characters "·" and "×" represent that the relative charges are +1 and zero, respectively. Therefore, it is known that the BZI hydrate exhibits proton conductivity in an inert atmosphere or air containing water vapor (References 1 and 2).

[0078] Returning to Figure 3, the electrical conductivities of Samples 11a to 17a in humid Ar gas had little difference due to the difference in composition. This is because the conduction mechanism in the BZI compound in a humid atmosphere is proton conduction via the hydration reaction according to the aforementioned Reaction formula E (References 3 to 5). For any sample, in the temperature range of 200 to 800 °C, the electrical conductivity improved with an increase in temperature with an activation energy of about 0.5 eV, and the electrical conductivity was about 7×10 -4 S / cm around 600 °C. These behaviors are also consistent with the reports in past literature (References 3 to 5).

[0079] However, in a dry hydrogen gas atmosphere, a significant difference was observed in the electrical conductivity of each sample. For Samples 11a and 12a (x = 0 and y = 0.3, 0.4), the slope of the electrical conductivity in dry hydrogen gas became gentler at temperatures above 300 °C compared to that in humidified Ar gas ((a) and (b) of Fig. 3). When calculating the activation energy from this slope, it was about 0.54 eV in humidified Ar gas, but decreased to about 0.38 eV in dry hydrogen gas. Furthermore, for Sample 12a, the conductivity in dry hydrogen gas showed a higher value than that in humidified Ar gas at temperatures above 500 °C.

[0080] The proton carriers in the BZI compound are brought about by the hydration reaction of Reaction Formula E above. However, in dry hydrogen gas, since sufficient proton generation by hydration does not occur, it is considered that conductivity not due to protons has occurred. Therefore, for Sample 11a, DC conductivity measurement was also carried out in dry hydrogen gas following the same procedure as the AC method. As a result, the conductivity measured by the DC method was in agreement with the conductivity measured by the AC method ((a) of Fig. 3). This indicates that electron conduction is occurring in dry hydrogen gas.

[0081] For Sample 13a (x = ￥0 and y = 0.5), the electrical conductivity in dry hydrogen gas was approximately twice that in humidified Ar gas at 800 °C and increased by one order at 400 °C compared to that in humidified Ar gas ((e) of Fig. 3). Furthermore, in the temperature range below 400 °C, the electrical conductivity of the sample was almost constant. This result is considered to be because the sample after heat treatment in dry hydrogen gas has an electrical conduction mechanism other than the conventionally reported proton conductivity, that is, electron conductivity.

[0082] For Samples 14a and 15a (x = 0 and y = 0.6, 0.7), the samples collapsed during the heat treatment at 800 °C, making measurement difficult. When XRD measurement (not shown) was performed on the collapsed samples, metallic In was detected. Therefore, in Samples 14a and 15a, it is considered that part of the In was reduced by the heat treatment at 800 °C in dry hydrogen gas, and metallic In was precipitated, decomposing the BZI compound. Thus, for Samples 14a and 15a, after heating in dry hydrogen gas at 700 °C for 30 hours, the electrical conductivity was measured again ((c) and (d) in Fig. 3). Compared with the electrical conductivity in humid Ar gas, the electrical conductivity of both samples increased in dry hydrogen gas, but the value was smaller than that of Sample 13a.

[0083] In Samples 16a and 17a (x = 0.1, 0.2 and y = 0.5) in which Ba, the A-site cation of the perovskite structure, was deficient, the electrical conductivity was greatly improved by the heat treatment in dry hydrogen gas ((f) and (g) in Fig. 3). That is, Samples 16a and 17a showed almost the same electrical conductivity as Sample 13a in the case of measurement in humid Ar gas, but showed a higher electrical conductivity than Sample  13a in the case of measurement in dry hydrogen gas. In Samples 16a and 17a, in the temperature range generally above 100 °C, the electrical conductivity was -2 10 S / cm or more and was almost constant. For Sample 17a, DC conductivity measurement was also performed in dry hydrogen gas in the same procedure as the AC method. As a result, the conductivity measured by the DC method was consistent with the conductivity measured by the AC method (Fig. 3(g)). This indicates that the relatively high conductivity in dry hydrogen gas is mainly due to electronic conduction.

[0084] In addition, for samples 13a, 16a, and 17a, after the electrical conductivity measurements of the In-reduced BZI compounds described above were completed, the electrical conductivity of the samples held at a relatively low processing temperature was also measured. Specifically, after the electrical conductivity measurements of the In-reduced BZI compounds described above were completed, the samples were heated at 300°C for 12 hours without changing the atmosphere, and the electrical conductivity was measured while increasing the temperature from 100°C to 800°C at a rate of 10°C / min. The samples at this time correspond to hydrogen-containing BZI compounds (compounds represented by general formulas (2a) to (2d)). The electrical conductivity obtained from this measurement was lower than that of the In-reduced BZI compounds (Figures 3(e) to (g)).

[0085] In other words, as shown in Figures 3(e) to (g), the electrical conductivity of the In-reduced BZI compound remains high in the temperature range of 100 to 800°C, while the electrical conductivity of the hydrogen-containing BZI compound decreases in comparison. As will be discussed later with respect to Figure 6, when the In-reduced BZI compound is heated in dry hydrogen gas at 300°C, hydrogen is introduced. Therefore, it is thought that the hydrogen dopant captures some of the electrons in the In-reduced BZI compound through the reaction shown in reaction equation F below, forming a hydride ion, which in turn reduces the concentration of conduction electrons and thus lowers the conductivity. [ka]

[0086] The reaction equation F is represented in Kroger-Vink notation, and e' and H i The symbols ' represent conduction electrons and hydride ions at interstitial sites, respectively.

[0087] In sample 19a, although the improvement was not as significant as in sample 17a, the electrical conductivity in dry hydrogen gas was improved compared to the electrical conductivity in humidified Ar gas (not shown).

[0088] From the above results, BZI compounds exhibit proton conductivity in humidified Ar gas. -4Although it exhibits a small electrical conductivity of about S / cm, it was found to show high electronic conductivity when heated in dry hydrogen gas and blackened. Furthermore, samples with Ba defects of about x ≤ 0.2 showed a larger electrical conductivity than samples without Ba defects, and generally exhibited a conductivity of 10 in the temperature range of 300°C or higher (especially 400°C or higher). -2 The compounds exhibited electrical conductivity of S / cm or higher. On the other hand, when the BZI compounds were exposed to hydrogen gas at a relatively low processing temperature after high-temperature heating (hydrogen introduction treatment), the conduction electron concentration decreased, and the electrical conductivity decreased.

[0089] Hereafter, we will describe in more detail the samples of composition examples 3, 6, and 7, which exhibit very high electronic conductivity when heated in dry hydrogen gas.

[0090] 1-6. TG Measurement Thermogravimetric (TG) measurements were performed on powder samples 13b, 16b, and 17b prepared in 1-1 above. The measurements were performed using a Netzsch STA2500 thermogravimetric analyzer at a heating rate of 2°C / min. The measurements were performed in three different atmospheres: (1) humidified Ar gas, (2) dry Ar gas, and (3) dry hydrogen gas.

[0091] Figure 4 shows the thermogravimetric curves of the BZI compound samples. In Figure 4, (a) is sample 13b (x=0 and y=0.5), (b) is sample 16b (x=0.1 and y=0.5), and (c) is sample 17b (x=0.2 and y=0.5). Figure 4(d) shows the weight change of each sample when the atmosphere is switched from dry Ar gas to dry hydrogen gas at 700°C.

[0092] In humidified Ar gas, a hydration reaction according to the above reaction equation E occurred at around 300°C, and the weight of the sample increased. However, as the temperature rose further, the sample gradually lost water above approximately 400°C, and the weight of the sample became almost constant above 500°C. From this, it was confirmed that a hydrate of the BZI compound can be obtained by heating at around 300°C in a humidified atmosphere, and that the hydrate gradually loses water and changes to an unhydrated phase by heating at around 400°C or higher.

[0093] In dry Ar gas, hydration does not occur, so dehydration occurs at around 250°C, and above 400°C, Ba 1-x Zr 0.5 In 0.5 O 2.75-x It appears that a non-hydrated phase with the following composition is being formed. In dry hydrogen gas, the weight of sample 13b decreased significantly above 450°C, and samples 16b and 17b decreased significantly above 400°C, with a plateau appearing above approximately 700°C in all samples. This indicates that when BZI compounds are heated in dry hydrogen gas, lattice oxygen is lost through reduction, and the BZI compounds change into a new phase.

[0094] When the atmosphere was switched from dry Ar gas to dry hydrogen gas, a clear weight loss was observed (Figure 4(d)). The weight losses of the samples were 1.59 wt% (sample 13b), 2.40 wt% (sample 16b), and 2.85 wt% (sample 17b), respectively. In dry Ar gas, at 700°C, almost no water (or OH groups) was lost in the BZI compounds, and Ba 1-x Zr 0.5 In 0.5 O 2.75-x It is thought that a non-hydrated phase with the following composition is being formed. Therefore, the weight loss in dry hydrogen gas is entirely due to lattice oxygen loss, and as a result, In is reduced to balance the charge.

[0095] 1-7. XAFS measurement X-ray absorption fine structure (XAFS) analysis was performed on powder samples 13b and 17b prepared in 1-1 above. XAFS measurements were performed at spring8 BL01. More specifically, XAFS spectra were measured using the transmission method with pelletized samples. The pelletized samples were obtained by mixing a powdered sample of the BZI compound with BN powder, a diluent, in an appropriate weight ratio, and then uniaxially molding the mixture into a shape with a diameter of 10 mm and a thickness of 1 mm. For each of samples 13b and 17b, three types of measurements were performed: (1) the sample as prepared according to 1-1 above, (2) the sample heated at 800°C in dry hydrogen gas for 5 hours, then the atmosphere was changed to dry Ar gas and rapidly cooled to room temperature at 50°C / min, and (3) the sample heated at 800°C in dry hydrogen gas for 5 hours, then cooled relatively slowly to room temperature at 3°C / min without changing the atmosphere. Furthermore, the sample described in (2) above, which was rapidly cooled in dry Ar gas, corresponds to an In-reduced BZI compound, while the sample described in (3) above, which was cooled relatively slowly in dry hydrogen gas, corresponds to a hydrogen-containing BZI compound.

[0096] Figure 5 shows the In-K edge XAFS spectra of the samples. In Figure 5, (a) is sample 13b (x=0 and y=0.5) and (b) is sample 17b (x=0.2 and y=0.5). Figure 5 also shows the XAFS spectrum of the reference material, In metal foil. The absorption edge of the In metal foil was 27942.7 eV.

[0097] Both the as-prepared samples 13b and 17b showed an absorption edge of approximately 27945.3 eV, which was significantly higher in energy than that of the In metal foil. These values ​​are in good agreement with those reported for oxides containing In(III) (Reference 6).

[0098] In samples 13b and 17b, which were rapidly cooled in Ar gas, the absorption edge was clearly shifted to the lower energy side. The absorption edge values ​​for the samples rapidly cooled in Ar gas were 27944.2 eV (sample 13b) and 27944.4 eV (sample 17b), respectively. It is generally known that the absorption edge of transition metal oxides shifts to the lower energy side as their average valency decreases (References 7 and 8). Therefore, in both samples 13b and 17b, it was found that the valency of some In was reduced from +3 to +1 or +2 by the heat treatment in dry hydrogen gas. This result is consistent with the aforementioned behavior of TG (Figure 4(d)), in which heat treatment in dry hydrogen gas causes weight loss due to lattice oxygen loss, resulting in the reduction of In.

[0099] On the other hand, the absorption edge of the sample cooled in dry hydrogen gas was at a higher energy than that of the sample cooled in dry Ar gas. This suggests that as the temperature decreases, the sample absorbs hydrogen from the atmosphere, and as a result, the valence of In, which was lowered by the heat treatment in dry hydrogen gas, increases during cooling.

[0100] The TG and XAFS measurement results above indicate that the reduction of In occurs due to oxygen deficiency caused by heating in dry hydrogen gas. Furthermore, considering the electrical conductivity results, it was found that the BZI compound is reduced and blackened in high-temperature dry hydrogen gas, transforming into an In-reduced BZI compound with high electrical conductivity. This high conductivity is attributed to the 5p on In(I) produced by the reduction of In(III). 2It is considered that electron pairs and 5p unpaired electrons on In(II) are involved. Considering that the conduction electrons (e’) are 5p electrons on In(I) and In(II), the hydrogen uptake reaction according to the above reaction formula F can be replaced by the oxidation reaction of In such as the oxidation of In(I) represented by the above reaction formula B. Therefore, when the In-reduced BZI compound is exposed to hydrogen gas at a relatively low treatment temperature, for example, hydrogen uptake according to the above reaction formula B occurs, and as a result, at least part of In is oxidized, such as In(I) being oxidized to In(III), and furthermore, hydride ions (H - ) are generated.

[0101] 1-8. NMR Measurement Regarding the powder samples 13b and 17b prepared in the above 1-1, 1 H-nuclear magnetic resonance ( 1 H-NMR) measurement was performed. The measurement was carried out by the magic angle rotation (MAS) method using Jeol JNM-ECAII, and the resonance frequency was set to 600 MHz. For each sample, two types of measurements were performed: (1) in the state as prepared according to the above 1-1, and (2) the sample prepared according to the above 1-1 was heated in dry hydrogen gas at 800 °C for 5 hours, and then, without changing the atmosphere, a hydrogen introduction treatment was carried out in which it was cooled relatively slowly to room temperature at 3 °C / min. The sample subjected to the hydrogen introduction treatment corresponds to a hydrogen-containing BZI compound (compounds represented by general formulas (2a) to (2d)).

[0102] Figure 6 shows the NMR measurement data of the samples. Figure 6(a) shows the measurement results of sample 13b, and Figure 6(b) shows the measurement results of sample 17b. In the figure, the dotted line shows the measurement data of the as-prepared sample, and the solid line shows the measurement data of the sample after the hydrogen introduction treatment. In both cases, the as-prepared samples show a broad peak around 7 ppm, which well coincides with the peak of protons derived from surface-adsorbed water (Reference 10). On the other hand, the sample slowly cooled after heating in dry hydrogen gas shows a sharp peak at 4.8 ppm, which coincides with the characteristics of hydride ions in the perovskite lattice (Reference 11).

[0103] From the conductivity, XAFS, and NMR measurements described above, it was found that exposing In-reduced BZI compounds to hydrogen gas at a relatively low processing temperature (hydrogen introduction treatment) introduces hydrogen into the In-reduced BZI compounds, generating hydride ions.

[0104] Furthermore, from the TG measurement results shown in Figure 4, it is possible to estimate the metal-oxygen stoichiometric composition, and based on this stoichiometric composition, the average valency of In in the sample can be calculated.

[0105] As mentioned above, regarding Figure 4(d), it can be inferred that in dry Ar gas, at 700°C, almost all water (or OH groups) in the BZI compound is lost, and a non-hydrated phase is formed. Therefore, in Figure 4(d), the weight loss when the sample is exposed to dry hydrogen gas at 700°C is entirely due to lattice oxygen loss due to In reduction, and it is assumed that there is no hydrogen storage at the same temperature. In this case, sample 13b (formula weight M=284.3) is calculated based on the weight loss due to oxygen loss (1.59 wt%), and BaZr 0.5 In 0.5 O 2.47 It is presumed that this compound BaZr will change to this. 0.5 In 0.5 O 2.47 This corresponds to the compound represented by x=0, y=0.5 and w=0.28 in general formula (1a). Similarly, sample 16b (M=269.0) and sample 17b (M=253.7) were determined based on the weight loss due to oxygen loss (2.40 wt% and 2.85 wt%), respectively, using Ba 0.9 Zr 0.5 In 0.5 O 2.25 and Ba 0.8 Zr 0.5 In 0.5 O 2.10 It is presumed that the former compound Ba 0.9 Zr 0.5 In 0.5 O 2.25 This corresponds to the compound represented by x=0.1, y=0.5, and w=0.4 in general formula (1a), and the latter compound Ba 0.8 Zr0.5 In 0.5 O 2.10 This corresponds to the compound represented by the general formula (1a) with x=0.2, y=0.5, and w=0.45.

[0106] The above stoichiometric composition shall be derived by the following method. In the TG measurement in Figure 4(d), it is assumed that the weight loss when the sample is exposed to dry hydrogen gas at 700°C is entirely due to lattice oxygen loss due to In reduction, and that there is no hydrogen storage at the same temperature. In the TG measurement in Figure 4(d), it can be seen that when each sample is heated in dry hydrogen gas at 700°C for 3 hours or more, its weight stabilizes and it changes into a stable phase with a specific composition. If the weight of the sample used in the TG measurement is m (g), and the weight loss obtained from the TG measurement results in Figure 4(d) is Δm (g), then the mole fraction w of lattice oxygen lost due to this weight loss is given by the following formula P.

number

[0107] Here, α is the ratio of weight loss (Δm / m) relative to the weight of the sample used. For example, the composition of samples 13b, 16b, and 17b (y=0.5) after TG measurement is Ba 1-x Zr 0.5 In 0.5 O 2.75-x-w Given by this, the result is as described above.

[0108] The average valency of In can be determined from the perspective of the overall charge balance of the composition by the following equation D'.

number

[0109] In formula D', the symbol Σ represents the summation of A-site atoms if there are multiple A-site atoms in the perovskite structure, and the summation of B-site atoms other than In if there are multiple B-site atoms. Also, "(+1)×H +The term "(-1) × H" indicates that the effect of the charge of a +1 valence hydrogen ion is taken into account when one is present, and is expressed as "(-1) × H - The term "proportion of" indicates that the effect of the charge of the -1 valent hydride ion should be taken into account when it is present. However, from the neutron diffraction results described later (Figure 8, Tables 6 and 7), the sample prepared by the method 1-1 above and treated with hydrogen contains almost no protons, and therefore, H in In-reduced BZI compounds and hydrogen-containing BZI compounds + The proportion of this is almost zero. If we assume the valencies of Ba, Zr, and O are +2, +4, and -2 respectively, then for example, in the case of composition example 3, based on the above stoichiometric composition, the average valency of In is calculated as -(2×1+4×0.5+(-2)×2.47) / 0.5, which is approximately 1.88.

[0110] The stoichiometric compositions and average valencies of In for samples 13b, 16b, and 17b, derived from the TG measurement results, are shown in Table 3. Note that in Table 3, the weight increase due to the introduction of hydrogen species by hydrogen heating at 700°C and its effect on charge compensation are ignored. That is, in the above equation D', "(+1) × H + "The ratio" and "(-1) × H - The term "proportion of" is set to zero. The reason for this is that, as shown in the SIMS measurement (Figure 7) described later, the samples that were rapidly cooled to room temperature after heating in dry hydrogen gas at 700°C (non-hydrogen-introduced samples 23e and 27e) contain only hydrogen with a formula weight of about 0.01, and therefore contribute almost nothing to the overall charge compensation. Furthermore, the atomic weight of hydrogen (1) is very small compared to the other constituent elements, and the weight increase due to the introduction of H with a formula weight of about 0.01 can be ignored.

[0111] The proportions of In(I), In(II), and In(III) in In were determined based on the average valency of In given by formula D', for each case where In is In(I) and In(III) (general formula (1b)), and where In(II) and In(III) or In(I) and In(II) (general formula (1c) or (1d)). As shown in Table 3, it was found that heating the BZI compound in a hydrogen atmosphere reduces In, yielding In-reduced BZI compounds (compounds shown by general formulas (1b), (1c), or (1d)).

[0112] [Table 3]

[0113] Example 2 2-1. Preparation of hydrogen-containing BZI compounds For composition examples 3, 6, and 7, powders and sintered bodies of hydrogen-containing BZI compounds were prepared. The hydrogen-containing BZI compound powder was obtained by heating the BZI compound powder prepared according to 1-1 above at 700°C for 24 hours in dry hydrogen gas, then lowering the temperature to 300°C at a rate of 10°C / min without changing the atmosphere, holding it for 12 hours, and finally cooling it to room temperature at a rate of 10°C / min (hydrogen introduction treatment). On the other hand, the method for preparing the sintered body of the hydrogen-containing BZI compound is as follows. First, 0.8 wt% NiO was added as a sintering aid to the BZI compound powder prepared according to 1-1 above, and this was molded using a uniaxial press and a hydrostatic press. This molded body was heated at 1500°C for 8 hours to obtain a dense sintered body consisting of the NiO-added BZI compound. Then, the following hydrogen introduction treatment was performed on this dense sintered body. That is, the dense sintered body was heated at 800°C in dry hydrogen gas for 30 hours to obtain a sintered body of the In-reduced BZI compound. Furthermore, this reduced In-type BZI compound was cooled to 300°C at a rate of 10°C / min in the same atmosphere, held for 12 hours, and finally cooled to room temperature at a rate of 10°C / min.

[0114] In addition to the above samples, for composition examples 3 and 7, samples of D-substituted compounds were prepared using deuterium gas (D2) instead of hydrogen gas in the atmosphere. The hydrogen-containing BZI compound (D-substituted compound) powder was obtained by heating the BZI compound powder prepared according to 1-1 above at 800°C for 5 hours in dry deuterium gas, and then cooling the temperature to room temperature at 3°C / min without changing the atmosphere (hydrogen introduction treatment). On the other hand, the method for preparing a sintered body of the hydrogen-containing BZI compound (D-substituted compound) is as follows. First, 0.8 wt% NiO was added as a sintering aid to the BZI compound powder prepared according to 1-1 above, and this was molded by a uniaxial press and a hydrostatic press. This molded body was heated at 1500°C for 8 hours to obtain a dense sintered body consisting of the NiO-added BZI compound. Then, the following hydrogen introduction treatment was performed on this dense sintered body. In other words, the dense sintered body described above was heated in dry hydrogen gas at 800°C for 30 hours to obtain a sintered body of the In-reduced BZI compound. Furthermore, this In-reduced BZI compound was cooled to 300°C at a rate of 10°C / min in the same atmosphere, held for 12 hours, and finally cooled to room temperature at a rate of 10°C / min.

[0115] Furthermore, for composition examples 3 and 7, sintered bodies of In-reduced BZI compounds were prepared by the following method. First, a dense sintered body consisting of a BZI compound with NiO added was obtained, similar to the method described above. This sintered body was heated in dry hydrogen gas at 800°C for 30 hours, and then rapidly cooled to room temperature at 50°C / min to obtain a sintered body of In-reduced BZI compound.

[0116] Below, each sample prepared according to this process is described with a sample number as shown in Table 4, depending on the composition example, sintered body, powder, and type of D-substituted body.

[0117] [Table 4]

[0118] 2-2.SIMS measurement Secondary ion mass spectrometry (SIMS) was performed on the D-substituted sintered body samples 23c, 23e, 27c, and 27e prepared in 1-1 and 2-1 above. The measurements were performed using a JEOL JMS-S3000, and Ga + Elemental analysis was performed from the surface to a depth of 3 μm while sputtering with an ion beam.

[0119] Figure 7 shows the SIMS profiles of the samples. In Figure 7, (a) sample 23c (hydrogen-containing BZI compound, x=0 and y=0.5), (b) sample 23e (In-reduced BZI compound), (c) sample 27c (hydrogen-containing BZI compound, x=0.2 and y=0.5), and (d) sample 27e (In-reduced BZI compound). The concentration profiles of Ba, Zr, In, and O are shown as intensities corrected by the sensitivity factor of each atom, and the concentration profile of the deuterium atom is shown as BaZr 0.8 Y 0.2 O 2.9-k (OD) 2k The concentrations shown are those determined based on a standard sample represented by (k=0.1). From this SIMS profile, it was found that the molar ratios of Ba, In, and Zr charged in 1-1 above were almost maintained in the sample after heat treatment.

[0120] In all samples, the concentration profiles of Ba, Zr, O, and In were generally flat within the bulk material beyond the surface layer to a depth of approximately 3 μm. Furthermore, in all samples, the intensities of In and Zr were equal to each other, approximately half the intensity of Ba, and consistent with the stoichiometric ratios of the metallic elements.

[0121] The concentration of D in sample 23c (hydrogen-containing BZI compound) (Figure 7(a)) is approximately 2.0 × 10 in the bulk material beyond a surface depth of 500 nm. 21 atom·cm -3 This corresponds to the hydrogen content at which the formula weight n is 0.15. On the other hand, the D concentration in sample 23e (In-reduced BZI compound) (Figure 7(b)) is approximately 1.3 × 10⁻⁶. 20 atom·cm -3Therefore, it can be seen that the D concentration is about an order of magnitude smaller by performing only the heat treatment that reduces In. Thus, it can be seen that hydrogen atoms are introduced into the In-reduced BZI compound by the hydrogen introduction treatment.

[0122] Considering the metal-oxygen composition ratio estimated based on TG measurements and the D concentration of the sample obtained by SIMS measurements, sample 23c is BaZr 0.5 In 0.5 O 2.47 H 0.15 It is presumed to have the following stoichiometric composition (the detailed derivation method will be described later). Here, the oxygen composition ratio after hydrogen introduction treatment was based on the values ​​in Table 3. This compound BaZr 0.5 In 0.5 O 2.47 H 0.15 This corresponds to the compound represented by the general formula (2a) where x=0, y=0.5, w=0.28, and n=0.15. In TG measurements, it was confirmed that the weight loss of oxygen under 800°C conditions was no different from the weight loss of oxygen under 700°C conditions. From the above stoichiometric composition, the average valence of In in sample 23c is approximately +2.18 based on formula D'. If In is In(I) and In(III), then the proportion of In(I) is 0.205. On the other hand, sample 23e is BaZr 0.5 In 0.5 O 2.47 H 0.010 It is presumed to have the following stoichiometric composition: This compound BaZr 0.5 In 0.5 O 2.47 H 0.010 This corresponds to the compound represented by the general formula (2a) where x=0, y=0.5, w=0.28, and n=0.010. The average valency of In in sample 23e is approximately +1.90, based on formula D'. This value is consistent with the value in Table 3, indicating that the average valency of In is hardly affected at a hydrogen concentration of around 0.01. The proportion of In(I) in sample 23e is 0.275.

[0123] Furthermore, the D concentration in sample 27c (hydrogen-containing BZI compound) (Figure 7(c)) was approximately 9.2 × 10 in the bulk material beyond a surface depth of 1000 nm. 21 atom·cm -3 This corresponds to the hydrogen content where the formula weight n is 0.68. On the other hand, the D concentration in sample 27e (In-reduced BZI compound) (Figure 7(d)) ​​is approximately 8.1 × 10⁻⁶. 20 atom·cm -3 Thus, as with composition example 3, it can be seen that the D concentration is about an order of magnitude smaller because only the heat treatment that reduces In was performed.

[0124] Considering the metal-oxygen composition ratio estimated based on TG measurement and the D concentration of the sample obtained by SIMS measurement, sample 27c is Ba 0.8 Zr 0.5 In 0.5 O 2.10 H 0.68 It is presumed to have the following stoichiometric composition: This compound Ba 0.8 Zr 0.5 In 0.5 O 2.10 H 0.68 This corresponds to the compound represented by x=0.2, y=0.5, w=0.45 and n=0.68 in general formula (2a). From the above stoichiometric composition, the average valency of In in sample 27c is approximately +2.56 based on formula D'. If In is In(I) and In(III), then the proportion of In(I) is 0.110. On the other hand, sample 27e is Ba 0.8 Zr 0.5 In 0.5 O 2.10 H 0.060 It is presumed to have the following stoichiometric composition: This compound Ba 0.8 Zr 0.5 In 0.5 O 2.10 H 0.060 This corresponds to the compound represented by x=0.2, y=0.5, w=0.45, and n=0.060 in general formula (2a). The average valency of In in this sample 27e is approximately +1.32, based on formula D'. If In is In(I) and In(III), then the proportion of In(I) is 0.420.

[0125] The above stoichiometric composition based on TG and SIMS measurement results shall be derived by the following method. From XRD measurement, the lattice constant of sample 23c was determined to be 4.199 Å. Therefore, the volume of the cubic perovskite unit cell of sample 23c is (4.199 Å). 3 = 7.403 × 10 -23 cm 3 Therefore, since there is one unit of perovskite structure within the unit cell, the density of sample 23c is 1 / (7.403 × 10⁻¹⁰). -23 ) = 1.35 × 10 22 Units: cm -3 Therefore, the formula weight n of hydrogen, using the D concentration measured by SIMS, is given by the following equation.

number

[0126] Assuming that the D concentration of each sample obtained from SIMS measurement corresponds to the H concentration in the hydrogen introduction treatment in dry hydrogen gas (H2), the net stoichiometric composition of the sample when hydrogen introduction treatment is performed in dry hydrogen gas is estimated as shown in Table 5. The stoichiometric composition is shown for the case where In is In(I) and In(III) (general formula (1b)), and for the case where In is In(II) and In(III) or In(I) and In(II) (general formula (1c) or (1d)).

[0127] [Table 5]

[0128] 2-3. XRD and NRD Measurement XRD measurements were performed on samples 13b, 16b, and 17b (before hydrogen introduction treatment) prepared according to 1-1 above, and on samples 23b, 26b, and 27b (after hydrogen introduction treatment) prepared according to 2-1 above. Furthermore, neutron diffraction (NRD) measurements using the Time of Fright method were performed on samples 13b and 17b (before hydrogen introduction treatment) prepared according to 1-1 above, and on samples 23d and 27d (after hydrogen introduction treatment) prepared according to 2-1 above. NRD measurements were performed using JASRI Spica. The Z-Rietveld program was used for Rietveld analysis of the NRD patterns.

[0129] Figure 2 shows the XRD patterns of each sample before and after hydrogen introduction treatment. In Figure 2, the solid line shows the XRD pattern of the BZI compound before hydrogen introduction treatment, and the dashed line shows the XRD pattern of the hydrogen-containing BZI compound after hydrogen introduction treatment. Samples 23b, 26b, and 27b (x≦0.2) turned black after hydrogen introduction treatment, but it can be seen that they maintained a single phase of the cubic perovskite type. Furthermore, from the lattice constants determined from the XRD patterns, it was found that the perovskite cubic lattice constant decreased by about 0.5% after hydrogen introduction treatment.

[0130] Figure 8 shows the NRD patterns and Rietveld calculation profiles for each sample. In Figure 8, (a) sample 13b (before hydrogen introduction treatment, x=0 and y=0.5), (b) sample 23d (after hydrogen introduction treatment), (c) sample 17b (before hydrogen introduction treatment, x=0.2 and y=0.5), and (d) sample 27d (after hydrogen introduction treatment).

[0131] As mentioned above, BZI compounds formed in unhydrated air, and BZI compounds formed in a room-temperature humidified atmosphere such as room-temperature humidified air (water vapor partial pressure 0.023 atm), are hardly hydrated, and their compositional formula is Ba1Zr 1-y In y O 3-0.5y-k (OH) 2kIt has been reported that k is approximately less than 0.01 (k<0.01) in this case (References 1 and 2). Therefore, k can be approximated as 0 in this composition. Rietveld analysis of the NRD pattern was performed on the as-prepared BZI compound sample, assuming k=0 and the structure of the BZI compound as a cubic perovskite (Pm-3m). As a result, the observed pattern and the calculated pattern were in good agreement with each other, so the structure and composition were identified under the above assumption.

[0132] Figure 9A is a conceptual diagram showing the positions of hydrogen atoms in a BZI compound having a perovskite-type structure. In Figure 9A, (a)H i (D i (b)H fcc (D fcc ) is a hydrogen atom (deuterium atom) located at the center of the

[0100] face in the perovskite structure, and (c)H O (D O ) represents a hydrogen atom (deuterium atom) at the oxygen site position.

[0133] Generally, when a proton is introduced into a perovskite according to the hydration reaction of reaction equation E above, the proton forms a hydrogen bond with the lattice oxygen and occupies a position of about 1 Å in the vicinity of the lattice oxygen (Figure 9A(a)). Previous reports (References 1 and 2) have shown that the position of the hydrogen atom in the BZI compound before hydrogen introduction treatment is the same site. The hydrogen (deuterium) at this position is H i (D i )

[0134] For the sample after hydrogen introduction treatment, the position of the hydrogen atoms is shown as H in Figure 9A(a). i In the analysis using only this method, the calculation pattern did not match the observed pattern well. However, the hydrogen atom position is the face-centered position shown in Figure 9A(b). fcc When this was added, the calculation pattern closely matched the observed pattern. Furthermore, the hydrogen atom position is the position of the oxygen site shown in Figure 9A(c). O Adding this also yielded better results. H iThe hydrogen atom at this position is part of the hydroxyl group (OH), and its valency is +1. fcc and H O In similar perovskite-type oxides, it has been reported that H is a hydride ion site (Reference 9), fcc and H O The valency of the hydrogen atom at position is -1.

[0135] The structural parameters and compositions determined by NRD Rietveld analysis are shown in Tables 6 (Composition Example 3) and 7 (Composition Example 7). In the NRD Rietveld analysis in Tables 6 and 7, "D(D O ")" represents a hydrogen atom (deuterium atom) at the oxygen site position, and "D(D fcc ")" represents the hydrogen atom (deuterium atom) located at the center of the

[0100] face in the perovskite structure. The hydrogen atom content in the composition formula is determined by the lattice site "D(D O )" and "D(D fcc The composition is obtained by multiplying the sum of the occupancy rates of each element by 3. The oxygen atom content in the empirical formula is obtained by multiplying the occupancy rate of the lattice site "O(3e)" by 3. The stoichiometric composition is shown for the case where In is In(I) and In(III) (general formula (1b)), and for the case where In is In(II) and In(III) or In(I) and In(II) (general formula (1c) or (1d)).

[0136] [Table 6]

[0137] [Table 7]

[0138] As shown in Table 6, in the case of sample 23d, most of the deuterium is D fcc D O The proportion of is very small. In the case of sample 27d (x=0.2 and y=0.5), D O The amount is Dfcc The amount was about the same as that of D. i The hydrogen atom in was not present. Comparing the results of sample 23d and sample 27d, it was found that in hydrogen-containing BZI compounds, deleting Ba resulted in D O It was shown that the proportion of is increasing. This is consistent with the results of TG measurements (Figure 4(d)) which show that lattice oxygen loss increases as the amount of Ba deficiency x increases. From the above, it was shown that hydride ions are generated in hydrogen-containing BZI compounds, and protons are almost absent.

[0139] Based on NRD Rietveld analysis, the compositions of each sample before and after hydrogen introduction treatment in Composition Example 3 are, respectively, BaZr 0.5 In 0.5 O 2.74 (Sample 13b, before hydrogen introduction treatment) and BaZr 0.5 In 0.5 O 2.53 D 0.16 (Sample 23d, after hydrogen introduction treatment) The latter compound was BaZr 0.5 In 0.5 O 2.53 D 0.16 This corresponds to the compound represented by general formula (2a) where x=0, y=0.5, w=0.22, and n=0.16. Considering the proportion of hydride ions, the average valence of In in sample 23d is +2.44. Therefore, the composition of sample 23d, which is a hydrogen-containing BZI compound, can be expressed more specifically by general formula (2b) as BaZr 0.5 In(I) 0.14 In(III) 0.36 O 2.53 D 0.16 Therefore, if we show it in general formula (2c), then BaZr 0.5 In(II) 0.28 In(III) 0.22 O 2.53 D 0.16 It was found that this was the case.

[0140] On the other hand, the compositions of each sample before and after the hydrogen introduction treatment in Composition Example 7 were, respectively, Ba 0.8 Zr 0.5 In 0.5 O 2.55(Sample 17b, before hydrogen introduction treatment) and Ba 0.8 Zr 0.5 In 0.5 O 2.28 D 0.21 (Sample 27d, after hydrogen introduction treatment) The latter compound Ba 0.8 Zr 0.5 In 0.5 O 2.28 D 0.21 This corresponds to the compound represented by x=0.2, y=0.5, w=0.27 and n=0.21 in general formula (2a). Considering the proportion of hydride ions, the average valence of In in sample 27d is +2.34. Therefore, the composition of sample 27d, which is a hydrogen-containing BZI compound, can be expressed more specifically by general formula (2b) as Ba 0.8 Zr 0.5 In(I) 0.165 In(III) 0.335 O 2.28 D 0.21 And, as shown by the general formula (2c), Ba 0.8 Zr 0.5 In(II) 0.33 In(III) 0.17 O 2.28 D 0.21 It was found that this was the case.

[0141] As described above, the unstoichiometric oxygen compositions of samples 13b, 23d, 17b, and 27d are in general agreement with the oxygen compositions obtained from TG (see Table 3).

[0142] From the above results, it was found that hydrogenation treatment of BZI compounds results in the reduction of In and the introduction of H, yielding hydrogen-containing BZI compounds (compounds represented by general formulas (2a) to (2d)) that contain hydride ions. Furthermore, hydrogenation treatment of BZI compounds results in hydrogen being introduced into two types of crystal sites H O and H fcc It has been revealed that it will be introduced.

[0143] 2-4. ESR measurement Electron spin resonance (ESR) spectra were measured for the D-substituted sintered body samples 23c, 23e, 27c, and 27e prepared in accordance with 1-1 and 2-1 above. The measurements were performed using an electron spin resonance measurement system (ESR04, KEYCOM). Figure 9B shows the ESR spectra of each sample. The solid lines represent spectra measured at room temperature (298K), and the dashed lines represent spectra measured at 77K.

[0144] In all samples, no ESR peaks indicating the presence of lone electrons appeared at 77K, but signals originating from lone electrons appeared at 298K. This result indicates that at 77K, the peak was 5p. 0 In(III) and 5p have electron configurations. 2 This indicates the coexistence of In(I) ions with electron configurations (all of which are ions without spin magnetic moment). On the other hand, at 298K, an asymmetric ESR signal was observed, and 5p 1 It was confirmed that In(II) with a spin magnetic moment is produced in the electron configuration. It is thought that as the temperature increases, charge averaging (delocalization) occurs between some or all of the In(III) and In(I) atoms according to reaction equation G, resulting in the production of In(II). [ka]

[0145] From this, it can be inferred that in reduced In BZI compounds and hydrogen-containing BZI compounds, In exists in the In(I) and In(III) states at around 77K. From this state, as the temperature increases, charge averaging becomes more likely, and it is thought that the In states progress through In(I), In(II), and In(III) to reach the In(I) and In(II) or In(II) and In(III) states above room temperature (298K). The temperature at which each state switches depends on the likelihood of In ions being adjacent in the perovskite lattice, in other words, the In content in the compound. This is because the higher the In content, the fewer isolated In ions there are, and the more likely charge averaging is to occur between adjacent In ions. For example, if y = 0.3 or greater in general formulas (1a) and (2a), there are hardly any isolated In ions in the compound. Therefore, the smaller of In(I) and In(III) is relatively easily consumed to produce In(II), and at room temperature (298K), In is thought to exist in either the In(I) and In(II) state or the In(II) and In(III) state.

[0146] The change in the ESR peaks of samples 23c and 23e was larger than that of samples 27c and 27e. This is consistent with the higher amount of In(II) with spin magnetic moment in the compounds of samples 23c and 23e.

[0147] Example 3 (Hydrogen-containing BZI compound sintered body) 3-1. Measurement of hydrogen permeability For the hydrogen-containing BZI compound of composition example 7, hydrogen permeability was evaluated as one of its physical properties. Figure 10 is a conceptual diagram showing the hydrogen permeability measurement system. After polishing both sides of the sintered sample 17a (10 mm in diameter, 1.2 mm thick), prepared according to 1-1 above, with SiC paper, electrodes were fabricated by baking Pt paste onto both sides. Alumina tubes were pressed against these electrodes with Pyrex® glass gaskets in between, and humidified or dry Ar was flowed at 30 sccm on one side, while dry or humidified hydrogen gas (hydrogen:nitrogen flow rate ratio = 1:1) was flowed on the other side. As described above, the sample was set in the apparatus and, while maintaining the predetermined temperature, the hydrogen permeability rate J was measured when a DC voltage of ±1.5 V or open-circuit potential (OCV) was applied to both Pt electrodes. H2 (mol·s -1 cm -2 The transmission rate was measured against the hydrogen concentration C on the Ar flow side. H2 (vol%) was quantified by gas chromatography and determined by the following formula. In the following formula, S disc F is the area of ​​the sintered disk. Ar This is the flux of Ar gas (30cm 3 ·min -1 ), and V s The standard volume of a gas at 25°C and 1 bar is (22.4 × 10⁻⁶). 3 cm 3 )

number

[0148] Furthermore, the hydrogen permeation rate J of the sintered body sample 27a (after hydrogen introduction treatment) prepared according to 2-1 above was also determined using the same procedure. H2 We measured it.

[0149] Figure 11 shows the hydrogen permeation rates (J) of (a) sample 17a and (b) sample 27a at each temperature. HThe following shows the hydrogen permeation rate (J) when a {Pt(re),50%-H2·N2||Ar,Pt(we)}-hydrogen concentration cell, with samples 17a and 27a as the separation membranes, is subjected to an open-circuit potential (OCV) → -1.5V constant voltage → +1.5V constant voltage at 30-minute or 40-minute intervals, and the hydrogen permeation rate (J) is shown. H The following measurements were taken: In Figure 11(a), the gases at both ends are humidified and contain a partial pressure of water vapor of 0.023 atm. In Figure 11(b), dry gas is supplied.

[0150] In the measurement of sample 17a, a humidifying gas was used, and since sample 17a has been transformed into a hydrated BZI compound by a hydration reaction, hydrogen transport occurs via proton conduction. Sample 17a showed a relatively large open-circuit voltage, which is consistent with the fact that the BZI compound hydrate has a proton transport fraction of approximately 1 (Reference 1). The BZI compound hydrate showed no hydrogen permeation at all at the open-circuit voltage. This is because the BZI compound hydrate does not exhibit electron conductivity, and therefore hydrogen transport occurs via the concentration gradient, i.e., H + and e - This indicates that mixed conduction is not occurring. This is consistent with the fact that this oxide has a proton transport fraction of 1 (References 1 and 2). On the other hand, when a DC voltage of -1.5V was applied to the low hydrogen partial pressure side, clear hydrogen permeability was observed. This is thought to be because the electric field pumps protons from the high hydrogen partial pressure side to the low oxygen partial pressure side. Also, the observed J H Conversely, when +1.5V was applied, no hydrogen permeability was observed, confirming that pumping did not occur.

[0151] Sample 27a, a hydrogen-containing BZI compound, exhibited significantly higher hydrogen permeability than sample 17a at temperatures of 400°C, 500°C, and 550°C, even at lower temperature ranges. Sample 27a showed a small positive open-circuit potential and clear hydrogen permeability at all temperatures. Therefore, it was suggested that hydrogen-treated sample 27a is a mixed conductor of hydride ion and electron conduction.

[0152] As expected from the electrical conductivity measurement results shown in Figure 3, sample 27a exhibited a higher DC current than the unprocessed sample. However, although sample 27a passed a current of several hundred mA when -1.5V was applied, no increase in transmission rate was observed at -1.5V, and the current increase at +1.5V was less than 5%. Therefore, it can be seen that sample 27a, which underwent hydrogen introduction treatment, has very high electronic conductivity and a relatively small hydride ion transport fraction.

[0153] Although not shown in the figures, similar hydrogen permeation rate measurements were performed on samples 13a and 23a. The hydrogen permeation rate of sample 23a was inferior to that of sample 27a, but improved compared to sample 13a. Furthermore, sample 23a exhibited similar mixed conductivity, although inferior to that of sample 27a. Also, although not shown in the figures, similar hydrogen permeation rate measurements were performed on samples 16a and 26a. The hydrogen permeation rate of sample 26a showed performance comparable to that of sample 27a, and was significantly improved compared to sample 16a. Furthermore, sample 26a exhibited similar mixed conductivity to that of sample 27a.

[0154] Example 4 4-1. Fabrication of Thin-Film Devices A thin-film device (composite component of the present invention) was fabricated by the following method, using a cermet porous body made of BZI compounds of composition examples 3, 6, and 7 and Ni metal as a support, on which a dense film of BZI compounds (approximately 20 μm thick) of composition examples 3, 6, and 7 was laminated. First, one of the powder samples 13b, 16b, and 17b prepared according to 1-1 above and NiO powder were mixed in a weight ratio of 55:45, and this mixture was uniaxially molded and hydrostatically pressed to produce a green disc (cermet support) with a diameter of 21 mm and a thickness of 2 mm. Next, a paste was prepared by dispersing one of the other samples 13b, 16b, and 17b (the same type used when fabricating the cermet support) prepared according to 1-1 above in alcohol, and this paste was spin-coated onto the green disc and fired at 1400°C for 6 hours. This resulted in the lamination of a BZI compound thin film on the surface of a composite ceramic made of NiO and BZI compounds. Finally, the composite ceramics and BZI compound thin film were heated at 700°C for 15 hours in dry hydrogen gas (H2:Ar flow rate ratio = 1:9), and then cooled to room temperature at 2°C / min in the same atmosphere to introduce hydrogen into the composite ceramics and BZI compound thin film, and to reduce NiO in the green disc to Ni, thereby making the green disc porous. The resulting thin-film measuring device comprises a cermet support and a hydrogen-containing BZI compound thin film (hereinafter also simply referred to as a hydrogen-containing BZI film) laminated on this support.

[0155] Figure 12(a) is a conceptual diagram of the thin-film device 10 fabricated by the method described above. The composite cermet 11 used as the support is Ba 1-x Zr 0.5 In 0.5 O 2.75-x-l H n The composite ceramic consists of a hydrogen-containing BZI compound 12 and Ni13 having compositions (x=0, 0.1, 0.2). The thin film on the support is Ba 1-x Zr 0.5 In 0.5 O 2.75-x-l H n The thin film 14 is made of a hydrogen-containing BZI compound having the composition (x=0, 0.1, 0.2).

[0156] 4-2. SEM Images Figures 12(b) to (e) are scanning electron microscope (SEM) images of the cross-section of the thin-film device shown in Figure 12(a). In Figure 12, (b) and (c) are surface images of the hydrogen-containing BZI film fabricated using sample 17b, and (d) and (e) are cross-sectional images of the thin-film device fabricated using sample 17b. Each hydrogen-containing BZI film was a uniform film with a thickness of approximately 20 μm. Furthermore, no cracks or delamination occurred in each hydrogen-containing BZI film even when the cermet support became porous.

[0157] 4-3. Measurement of hydrogen permeability of thin-film devices Figure 13 is a graph showing the relationship between temperature and hydrogen permeability for each thin-film device obtained in 4-1 above. In Figure 13, the hydrogen permeability is shown in Arrhenius plot format. The hydrogen permeability was measured using the same method as described for Figure 10. Humidified hydrogen gas (hydrogen:nitrogen flow rate ratio = 1:1) was supplied to the support side, and at the same time, pure Ar gas was supplied to the hydrogen-containing BZI film side, and the hydrogen and nitrogen that permeated from the support side were quantified by gas chromatography. As a result, hydrogen permeation gas was detected in all thin-film devices, while nitrogen permeation gas was hardly detected. This indicates that selective hydrogen permeation occurs in the thin-film devices. The thin-film devices using sample 17b (x=0.2) and sample 16b (x=0.1) showed higher hydrogen permeability than the thin-film device using sample 13b (x=0). Furthermore, in the case of the thin-film devices using samples 17b and 16b, the hydrogen permeability in the temperature range of 400~600°C was comparable to that of PdAg alloy (Figure 13). From the above, it was shown that thin films of hydrogen-containing BZI compounds exhibit remarkable hydrogen permeability.

[0158] Example 5 5-1. Fabrication of fuel cells A fuel cell 20 was fabricated using a thin-film device based on the hydrogen-containing BZI compound of Composition Example 7 as a hydrogen-permeable anode. Figure 14(a) shows a conceptual diagram of the fabricated fuel cell 20. Following the same procedure as in 4-1 above, a thin-film device was fabricated by using a composite cermet 21 made of the hydrogen-containing BZI compound of Composition Example 7 and Ni metal as a support, and laminating a dense film 22 (approximately 20 μm thick) of the hydrogen-containing BZI compound of Composition Example 7 on top of it. BaZr was applied to the surface of this dense film. 0.1 Ce 0.7 Y 0.2 A thin film 23 (1 μm thick) of O3(BZCY) electrolyte was deposited by high-frequency sputtering. The sputtering deposition conditions are summarized in Table 8 below. Here, BaCe 0.8 Y 0.2 O3 and Zr 0.9 Y 0.1 The film was deposited by simultaneous sputtering using an O2 target.

[0159] High-frequency sputtering conditions for BZCY electrolyte thin films [Table 8]

[0160] Next, La, a common fuel cell cathode material, is applied to the BZCY electrolyte thin film 23. 0.6 Sr 0.4 Co 0.2 Fe 0.8 A porous cathode 24 (30 μm thick) was formed by screen printing an O3(LSCF) powder paste (manufactured by Fuel Cell Materials Co., Ltd.) to obtain a fuel cell 20. The fabricated fuel cell was installed in a self-made fuel cell station, and a power generation test was conducted by supplying humidified air (H2O / O2 / Ar=3 / 20 / 77) to the cathode side and pure hydrogen to the anode side at 50 sccm. The current-voltage curve and current-power curve of the fuel cell were measured using a Solartron 1268 / 1270 electrochemical analyzer.

[0161] 5-2. SEM Images Figures 14(b) to 14(d) show cross-sectional SEM images of the fuel cell. Figure 14(c) is a magnified image of region R1 in Figure 14(b), and Figure 14(d) is a magnified image of region R2 in Figure 14(c). It can be seen that a uniform BZCY electrolyte thin film is formed on the thin film device.

[0162] 5-3. Power characteristics of fuel cells Figure 15 shows the power characteristics (current-voltage-power curve) of the fuel cell. At 600°C, the open-circuit voltage is 1.05V and the peak power is 0.27W / cm². 2 This was demonstrated. Furthermore, the open-circuit voltage increased with decreasing temperature, reaching 1.13V at 500°C. From the above, it was proven that the hydrogen-permeable material containing the hydrogen-containing BZI compound of the present invention functions well as a hydrogen-permeable anode for fuel cells and is also stable in the fuel cell environment.

[0163] References 1.I. Ahmed, S.-G. Eriksson, E. Ahlberg, CS Knee, M. Karlsson, A. Matic, D. Engberg, L. Boerjesson, Solid State Ionics 177 (2006) 2357. 2.Istaq Ahmed, Christopher S. Kneeb, Maths Karlsson, S.-G. Eriksson, Paul F. Henry, Aleksandar Matic, Dennis Engberg, Lars Boerjesson, J. Alloys Compd 450 (2008) 103. 3.I. Ahmed, S.-G. Eriksson, E. Ahlberg, CS Knee, P. Berastegui, L.-G. Johansson, H. Rundloef, M. Karlsson, A. Matic, L. Boerjesson, D. Engberg, Solid State Ionics 177 (2006) 1395. 4.Istaq Ahmed, Francis G. Kinyanjui, Patrick Steegstra, Zhijian J. Shen, Sten-G. Eriksson, Mats Nygren, Electrochem. Solid-State Lett. 13 (2010) B130. 5.Wenping Sun, Zhiwen Zhu, Zhen Shi, Wei Liu, J. Power Sources 229 (2013) 95. 6.A. Tsoukalou, PM Abdala, D. Stoian, X. Huang, M.-G. Willinger, A. Fedorov, CR Muller, J. Am. Chem. Soc. 141 (2019) 13497. 7.D. Joseph, AK Yadav, SN Jha, D. Bhattacharyya, Bull. Mater. Sci. 36 (2013) 1067. 8.BD Shrivastava, J. Phys.: Conf. Sir. 365 (2012) 012002. 9.N. Masuda, Y. Kobayashi, O. Hernandez, T. Bataille, S. Paofai, H. Suzuki, J. Ritter, N. Ichijo, Y. Noda, K. Takegoshi, J. Tassel, T. Yamamoto, H. Kageyama, J. Am. Chem. Soc. 137 (2015) 15315. 10.I. Oikawa and H. Takamura, Chem. Mater., 27, 6660 (2015) 11.Y. Kobayashi et al., Nature Mater., 11, 507 (2012)

I'm sorry, I'm sorry

[0164] The hydrogen permeable material of the present invention is useful as a material for fuel cells.

Claims

1. A hydrogen permeable material containing a perovskite-type compound represented by the following general formula (1a). 【Chemistry 1】 (In formula (1a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.

75. w is a value such that the average value of In is between +1.0 and +2.

5. y ≥ w.

2. The hydrogen permeable material according to claim 1, wherein In is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valence of +3.

3. The hydrogen permeable material according to claim 2, wherein the perovskite compound represented by general formula (1a) is represented by the following general formula (1b). 【Chemistry 2】

4. The perovskite compound represented by general formula (1a) contains In(II) and is represented by the following general formula (1c) or general formula (1d), as described in claim 2, for hydrogen permeable material. 【Transformation 3】

5. The hydrogen permeable material according to any one of claims 1 to 4, wherein the average valency of In is the average valency determined from the mass change in the thermal analysis of the perovskite-type compound.

6. A perovskite-type compound represented by the general formula (1a) described in claim 1 contains a hydride ion (H － A hydrogen permeable material containing a hydrogen-containing perovskite compound (hereinafter referred to as a hydrogen-containing perovskite compound), wherein the molar ratio of hydride ion content n to w (n / w) is 2 or less.

7. The hydrogen-containing perovskite compound is represented by the following general formula (2a), as described in claim 6, for the hydrogen permeable material. 【Chemistry 4】 (In formula (2a), M is at least one alkaline earth metal selected from the group consisting of Ba, Sr, and Ca, H is a hydride ion, x is a number between 0 and 0.3, y is a value greater than 0 and less than or equal to 0.

75. w is the value at which the average value of In is greater than +1.0 and less than or equal to +3.

0. y ≥ w, and n / w ≤ 2.

8. The hydrogen permeable material according to claim 7, wherein In is In(I), In(I) and In(II), In(II) and In(III), In(I) and In(III), or In(I), In(II) and In(III). (However, In(I) is In with a valence of +1, In(II) is In with a valence of +2. In(III) is In with a valence of +3.

9. The hydrogen-containing perovskite compound represented by general formula (2a) is represented by the following general formula (2b), the hydrogen permeable material according to claim 8. 【Transformation 5】

10. The hydrogen-containing perovskite compound represented by general formula (2a) contains In(II) and is represented by the following general formula (2c) or general formula (2d), as described in claim 8, for the hydrogen permeable material. 【Transformation 6】

11. The hydrogen permeable material according to any one of claims 6 to 10, wherein the hydride ion content of the hydrogen-containing perovskite-type compound is determined by secondary ion mass spectrometry or neutron diffraction.

12. A hydrogen permeable material containing a hydrate of a perovskite-type compound according to any one of claims 1 to 5, or a hydrate of a hydrogen-containing perovskite-type compound according to any one of claims 6 to 11.

13. The hydrogen permeable material according to claim 12, wherein the hydrate is a hydrate represented by any one of the following general formulas (3a) to (3d) or any one of the following general formulas (4a) to (4d). 【Transformation 7】 (Formula (3a) represents the hydrate of the compound shown in formula (1a), and M, x, y, and w in formula (3a) are equivalent to those in formula (1a), Formula (3b) represents the hydrate of the compound shown in formula (1b), and M, In(I), In(III), x, y, and w in formula (3b) are equivalent to those in formula (1b). Formula (3c) represents the hydrate of the compound shown in formula (1c), and M, In(II), In(III), x, y, and w in formula (3c) are equivalent to those in formula (1c). Formula (3d) represents the hydrate of the compound shown in formula (1d), and M, In(I), In(II), x, y, and w in formula (3d) are equivalent to those in formula (1d). Formula (4a) represents the hydrate of the compound shown in formula (2a), and the M, n-labeled H, x, y, w, and n in formula (4a) are equivalent to those in formula (2a). Formula (4b) represents the hydrate of the compound shown in formula (2b), and in formula (4b), M, In(I), In(III), H with n attached, x, y, w, and n are equivalent to those in formula (2b). Formula (4c) represents the hydrate of the compound shown in formula (2c), and in formula (4c), M, In(II), In(III), H with n attached, x, y, w, and n are equivalent to those in formula (2c). Formula (4d) represents the hydrate of the compound shown in formula (2d), and the M, In(I), In(II), H, x, y, w, and n in formula (4d) are equivalent to those in formula (2d). l is a positive number that satisfies the condition l < x + 0.5y + w.

14. The hydrogen permeable material according to any one of claims 1 to 13, wherein the perovskite compound represented by general formula (1a) to (1d), the hydrogen-containing perovskite compound represented by general formula (2a) to (2d), or the hydrate represented by general formula (3a) to (3d) or (4a) to (4d) is a compound in which a portion of the B-site elements Zr and In are substituted with at least one element selected from the group consisting of rare earth elements, Ni, and Zn.

15. A composite member having a hydrogen permeable layer made of the hydrogen permeable material described in any one of claims 1 to 14 on at least a portion of the surface of a porous substrate.

16. The composite member according to claim 15, wherein the porous substrate is a cermet substrate, and the ceramic component of the cermet substrate is a hydrogen permeable material according to any one of claims 1 to 14.

17. A fuel cell having an anode layer, an electrolyte layer, and a cathode layer in this order on at least a portion of one main surface of a porous substrate, the anode layer containing the hydrogen permeable material described in any one of claims 1 to 14.

18. The fuel cell according to claim 17, wherein the porous substrate and the anode layer are composite members according to claim 15 or 16.

19. The electrolyte layer is BaZr ｘ Ce １－ｘ－ｚ Y ｚ O ３ A fuel cell according to claim 17 or 18, wherein (x = 0.1 to 0.8, z = 0.1 to 0.25, x + z ≤ 1.0).

Images