Patent ID: 6531073
Filing Date: 2003-03-11
Classification: C09K,G21K

Abstract:
A method for preparing a rare earth activated alkaline earth metal fluorohalide stimulable phosphor represented by the following formula (1):(Ba1âˆ’xM2x)FBryI1âˆ’y:aM1, bLn, c0â€ƒâ€ƒformula (1) wherein M1 is at least an alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M2 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 numbers meeting the following requirements:0&lE;x&lE;0.5, 0&lE;y&lE;1, 0&lE;a&lE;0.050the method comprising the steps of:(a) preparing an aqueous mother liquor containing BaX2 of not less than 2.0 mol/l and a halide of Ln, in which X is Br or I, provided that when x of the formula (1) is not zero, the mother liquor further contains a halide of M2, and when a is not zero, the mother liquor further contains a halide of M1, (b) adding an aqueous solution containing an inorganic fluoride of not less than 8 mol/l to the mother liquor while maintaining a temperature of at least 50Â° C. to form a crystalline precipitate of a precursor of the stimulable phosphor, (c) separating the precipitate of the precursor from the mother liquor, and (d) calcining the separated precipitate; and wherein the method further comprises:adding a compound represented by the following formula (2): AlBmOnâ€ƒâ€ƒformula (2) wherein A represents a hydrogen atom or at least an element selected from the group consisting of groups 1 and 2 of the periodic table; B represents at least an element selected from the group consisting of groups 13 through 17 of the periodic table; l, m and n each are an integer of 1 or more.