Patent ID: 7507289

Claim:
A method for manufacturing a 12CaO·7Al 2 O 3 compound, a 12SrO·7Al 2 O 3 compound, or a mixed crystal compound containing 12CaO·7Al 2 O 3 and 12SrO·7Al 2 O 3 comprising: electrons substituted for free oxygen ions at a concentration of 1×10 18 to less than 1.1×10 21 /cm 3 out of free oxygen ions contained in cages at a substitution ratio of the electrons to the free oxygen ions of 2 to 1, the concentration of the electrons being 2×10 18 to less than 2.2×10 21 /cm 3 in the cages, wherein the electrical conductivity at room temperature is in the range of 10 −4 S/cm to less than 10 3 S/cm, comprising the step of: holding a single crystal 12CaO·7Al 2 O 3 compound or a hydrostatic pressure press molded material of a fine powder thereof, a single crystal 12SrO·7Al 2 O 3 compound or a hydrostatic pressure press molded material of a fine powder thereof, or a single crystal of a mixed crystal compound containing a 12CaO·7Al 2 O 3 compound and a 12SrO·7Al 2 O 3 compound or a hydrostatic pressure press molded material of a fine powder thereof at 600 to 800° C. for 4 to less than 240 hours in an alkaline metal vapor or an alkaline earth metal vapor, whereby electrons are substituted for the free oxygen ions.