Photostimulable phosphor for use in radiography

A photostimulable rare earth metal doped barium strontium fluoride phosphor, characterized in that said phosphor is within the scope of the following empirical formula (I):

• Ba.sub.1-x Sr.sub.x F.sub.2-a-b Br.sub.a X.sub.b :zEu.sup.2+
• wherein:
• X is at least one member selected from the group consisting of Cl and I;
• x is in the range 0.06.ltoreq.x.ltoreq.0.50;
• a is in the range 0.75.ltoreq.a.ltoreq.0.96;
• b is in the range 0.ltoreq.b<0.15, and
• z is in the range 10.sup.-7 .ltoreq.z.ltoreq.0.15
• said phosphor being obtained by:
• admixing the following starting materials:
• (1) barium fluoride;
• (2) a strontium halide,
• (3) at least one Eu containing compound selected from the group consisting of europium halide, europium oxide, europium nitrate and europium sulphate, and
• fusing an intimate mixture of said ingredients with NH.sub.4 Br as the bromide source and optionally with NH.sub.4 X, X being as defined above, in a reducing atmosphere for transforming Eu.sup.3+ into Eu.sup.2+, the total gram atoms of X and Br being such that stoichiometrically the concentration of F in the final product exceeds that of Br and other halides to obtain a product having said empirical formula (I) with Sr being present substantially in a Matlockite structure.