Phase transitions in silver halides: silver iodide and its solid solutions with silver bromide

Abstract

There is no doubt of the existence of the B3 polytype of Agl. Both the B3 and B4 phases of Agl transform into the B23 phase around 145°C; there is no evidence for the B3→B4 transformation. The phase transitions of Agl, AgBr, and AgCl can be satisfactorily explained on the basis of the Born treatment of ionic solids. About 10 moles % AgBr enters into solid solution with the B3, B4, or B23 phase of Agl; about 25% Agl enters into solid solution with the B1 form of AgBr. We have reported the phase transitions of the Agl-AgBr solid solutions and a partial phase diagram of the system. The Born model explains the stability of the B1 form of the solid solution above ca. 10% AgBr.