Proton-conducting composite oxide powder and method for producing the same

Abstract

It has a fine particle size suitable for electrolyte membrane fabrication, and is made of BaSc 0.8 Mo 0.2 O 3-δ The present invention provides proton-conducting composite oxide powders with a high content of [a specific substance] and methods for producing the same. [Solution] The proton-conducting composite oxide powder of the present invention is BaSc x M 1-x O 3-δ The present invention provides a method for producing a proton-conducting composite oxide powder that contains 60% by volume or more of the composite oxide represented by the formula, and has an average particle size of 0.05 μm or less. The present invention provides a method for producing a proton-conducting composite oxide powder that includes a precipitation step of adding at least one aqueous solution of a hydrochloric acid-based aqueous solution and a nitric acid-based aqueous solution, which has a pH of less than 2 and contains Ba ions, Sc ions, and ions of element M (M is one or more elements selected from Mo and W), to an alkaline aqueous solution to adjust the pH of the alkaline aqueous solution to 10 or more and less than 14 to obtain a precipitate, or a precipitation step of adding at least one aqueous solution of a hydrochloric acid-based aqueous solution and a nitric acid-based aqueous solution, which has a pH of less than 2 and contains Ba ions and Sc ions, to an alkaline aqueous solution, which has a pH of less than 14 to adjust the pH of the alkaline aqueous solution to 10 or more and less than 14 to obtain a precipitate, a drying step of drying the precipitate at a predetermined temperature to obtain a precursor powder, and a calcination step of calcining the precursor powder at a temperature of 700°C or higher.

Claims

[Claim 1] A proton-conducting composite oxide powder containing 60% by volume or more of a composite oxide represented by the following compositional formula (1), and having an average particle size of 0.05 μm or less. BaSc ｘ M １－ｘ O ３－δ (1) Here, M is one or more elements selected from Mo and W, x is between 0.6 and 0.9, and δ is between 0 and 2.

0. [Claim 2] Specific surface area is 1.5 m² ２ / g or more 100.0m ２ The proton-conducting composite oxide powder according to claim 1, wherein the amount is less than or equal to / g. [Claim 3] The proton-conducting composite oxide powder according to claim 1 or 2, comprising 90% by volume or more of a composite oxide represented by the following compositional formula (1). BaSc ｘ M １－ｘ O ３－δ (1) Here, M is one or more elements selected from Mo and W, x is between 0.6 and 0.9, and δ is between 0 and 2.

0. [Claim 4] Sc ２ O ３ , BaCO ３ The proton-conductive composite oxide powder according to claim 3, wherein the total content of Sc, O, BaCO, and graphite is less than 5% by volume. [Claim 5] A precipitation step to obtain a precipitate by adding at least one aqueous solution of hydrochloric acid-based aqueous solution and nitric acid-based aqueous solution, which contains Ba ions, Sc ions, and ions of element M (where M is one or more elements selected from Mo and W), and has a pH of less than 2, to an alkaline aqueous solution, thereby adjusting the pH of the alkaline aqueous solution to 10 or more and less than 14. Alternatively, a precipitation step is performed by adding at least one aqueous solution of a hydrochloric acid-based aqueous solution and a nitric acid-based aqueous solution, which contain Ba ions and Sc ions and have a pH of less than 2, to an alkaline aqueous solution containing ions of element M (where M is one or more elements selected from Mo and W), thereby adjusting the pH of the alkaline aqueous solution to 10 or more and less than 14 to obtain a precipitate. A drying step of drying the precipitate at a predetermined temperature to obtain a precursor powder, and A method for producing a proton-conducting composite oxide powder, comprising a calcination step of calcining the precursor powder at a temperature of 700°C or higher. [Claim 6] The precursor powder is BaCO ３ or Ba(OH) ２ The process further includes a mixing step of mixing with to obtain a mixture, The method for producing a proton-conducting composite oxide powder according to claim 5, wherein the calcination step involves calcining the mixture. [Claim 7] The mixing step involves the precursor powder and the BaCO3. ３ or Ba(OH) ２ The mixing ratio of the precursor powder and the BaCO2 is such that the weight ratio is 1:X (where X is less than 2.0). ３ or Ba(OH) ２ Mix them together, The method for producing a proton-conducting composite oxide powder according to claim 6, wherein the firing step involves firing the mixture under firing conditions of a firing temperature of 800°C or more and 1500°C or less and a firing time of 1 hour or more.

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