Patent ID: 7422705

Claim:
A method of preparing a precursor of a rare earth activated alkaline earth metal fluorohalide stimulable phosphor represented by the following formula (1) Ba (1-x) M 2(x) FBr (y) I (1-y) :aM 1 , bLn, cO formula (1) wherein M 1 is at least an alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M 2 is at least an alkaline earth metal selected from the group consisting of Be, Mg, Ca and Sr; Ln is at least one rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm, Dy, Ho, Nd, Er and Yb; and x, y, a, b and c are values meeting the following conditions: 0 ≦x≦ 0 . 3 , 0 ≦y≦ 0.3, 0 ≦a≦ 0.05 0 <b≦ 0.2 and 0 ≦c≦ 0.1, the method comprising the steps of: (A) adding an aqueous solution of an inorganic fluoride into a mother liquor containing a barium halide to form a reaction mixture containing a precursor of the stimulable phosphor over a period of “a”, and (B) removing a solvent from the reaction mixture over a period of “b” to concentrate the reaction mixture, wherein the steps (A) and (B) are started at the same time, and meeting the following requirement: 0.25<a/b<0.95.