Process for producing scintillation materials of low strain birefringence and high refractive index uniformity

A process for producing a scintillation material, said scintillation material comprising a compound of general empirical formula LnX3 or LnX3:D, wherein Ln is at least one member selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu;

• X is selected from the group consisting of F, Cl, Br and I;
• and D is at least one cationic dopant comprising one or more element selected from the group consisting of Y, Zr, Pd, Hf and Bi and said at least one cationic dopant is present in the material in an amount of 10 ppm to 10,000 ppm;
• said process comprising the steps of:
• a) optionally mixing the compound of the general empirical formula LnX3 with the at least one cationic dopant to obtain a mixture;
• b) heating the compound or the mixture obtained by the optional mixing to a melting temperature thereof;
• c) then growing the crystal or crystalline structure;
• and
• d) cooling the crystal or crystalline structure obtained by the growing from a growing temperature of the crystal or the crystalline structure to a temperature of 100° C. at a cooling rate of less than 20 K/h.