Patent ID: 8178001

Claim:
A method, comprising firing a feedstock prepared by mixing compounds serving as sources of Al, Si, the element represented by M1, and the element represented by M2, wherein the amount of Si in the feedstock is greater than one mole and less than 1.14 moles per mole of Al, to obtain an inorganic compound represented by formula (I): M1 a M2 b AlSiX 3 (I) where M1 represents an activation element comprising at least Eu, M2 represents at least one or more alkaline-earth metal element, X represents one or more selected from the group consisting of O and N, and a and b each represent a positive number where 0<a ≦0.1 and 0.8≦a +b≦1, wherein a source of the element represented by M1 is a halide.