Patent ID: 7722846

Claim:
A method for preparing an electroconductive mayenite type compound, comprising subjecting a precursor to a heat treatment, wherein the precursor is a vitreous or crystalline material, which comprises Ca and Al, in which a molar ratio of CaO:7Al 2 O 3 is from 12.6:6.4 to 11.7:7.3 calculated as oxides, and in which a total amount of CaO and Al 2 O 3 is at least 50 mol %, and wherein the heat treatment is a heat treatment comprising holding the precursor at a heat treatment temperature T of from 600 to 1,415° C. in an inert gas or vacuum atmosphere with an oxygen partial pressure P O2 in a range of P O2 ≦10 5 ×exp[{−7.9×10 4 /(T+273)}+14.4] in the unit of Pa.