Patent ID: 7128995

Claim:
A method of producing an oxide ion conductor comprising a composite oxide which has constituent elements of a trivalent element A, a tetravalent element B, and oxygen O, said composite oxide has a composition formula represented by A X B 6 O 1.5X+12 provided that 8≦X≦10, said composite oxide has an apatite type crystalline structure, said oxide ion conductor has anisotropy in oxide ion conductivity, said method of producing said oxide ion conductor comprising: a first step of mixing a powder of a substance having constituent elements of said element A and oxygen O with a powder of a substance having constituent elements of said element B and oxygen O in a ratio to produce A X B 6 O 1.5X+12 provided that 8≦X≦10, for obtaining a mixed powder; a second step of heating said mixed powder for preparing said composite oxide having said composition formula represented by A X B 6 O 1.5X+12 provided that 8≦X≦10; a third step of adding said composite oxide to a solvent for preparing a slurry, and then solidifying said slurry in a magnetic field for preparing a compact; and a fourth step of sintering said compact for preparing said oxide ion conductor of said composite oxide.