Patent ID: 8557216

Claim:
An aluminum magnesium titanate crystal structure, which comprises a solid solution of aluminum magnesium titanate crystal represented by the empirical formula Mg x Al 2(1−x) Ti (1+x) O 5 , where 0.1≦x<0.5 and 0.1 to 1 mol % of Al atoms are substituted with Si atoms, wherein some Al atoms in a surface layer of the aluminum magnesium titanate crystal are substituted with Si atoms; the aluminum magnesium titanate crystal has a thermal expansion coefficient of from −6×10 −6 (1/K) to 6×10 −6 (1/K) in a range of from 50 to 800° C. at a temperature raising rate of 20° C./min; and the aluminum magnesium titanate crystal has a remaining ratio, α, of aluminum magnesium titanate of at least 50%, after heating in an atmosphere of 1,100° C. for 300 hours, where α=100( R/R 0 ), R 0 =I MAT(023) /( I MAT(023) +I TiO2(110) ) before the heating, R=I MAT(023) /( I MAT(023) +I TiO2(110) ) after the heating, I MAT(023) is an integrated intensity of a X-ray diffraction peak from the aluminum magnesium titanate corresponding to the (023) face of aluminum magnesium titanate, and I TiO2(110) is an integrated intensity of an X-ray diffraction peak from the aluminum magnesium titanate corresponding to the (110) face of rutile.