Crystal material, crystal production method, radiation detector, non-destructive inspection device, and imaging device

A crystal material having a pyrochlore structure, non-stoichiometric composition, and congruent melting composition represented by general formula (1): ＲＥ x Ａ １－x－y―ｓ Ｂ ｙ Ｍ' ｓ ） ２+α （Ｓｉ １－ｔ ,Ｍ" ｔ ） ２+β Ｏ ７+γ . Wherein A includes at least one selected from Gd, Y, La, Sc, Yb, and Lu; B includes at least one selected from La, Gd, Yb, Lu, Y, and Sc; ０.１ ＜ ｙ ＜ ０．４; RE includes at least one selected from Ce, Pr, Nd, Eu, Tb, and Yb; ０ ＜ ｘ ＜ ０．１; M' and M'' include at least one selected from Ｌｉ，Ｎａ，Ｋ，Ｍｇ，Ｃａ，Ｓｒ，Ｂａ，Ｔｉ，Ｚｒ，Ｈｆ，Ｆｅ、Ｔａ，and W; ０ ≦ ｓ ＜ ０．０１ and ０ ≦ ｔ ＜ ０．０１; and ０ ＜ |α| ＜０．３, ０ ≦ |β| ＜ ０．３, and ０ ≦ |γ| ＜ ０．５.