In Search of a Double Perovskite in the Phase Triangle of Bromides CsBr-CuBr-InBr(3)

New bromide compounds A(2)B(I)B(III)Br(6) with a double perovskite structure provide variety and flexibility of optoelectronic properties, and some of them are of poor toxicity in comparison with such popular lead halides. The promising compound with a double perovskite structure was proposed recently for the ternary system of CsBr-CuBr-InBr(3). Analysis of phase equilibria in the CsBr-CuBr-InBr(3) ternary system showed stability of the quasi-binary section of CsCu(2)Br(3)–Cs(3)In(2)Br(9). Formation of the estimated phase Cs(2)CuInBr(6) by melt crystallization or solid-state sintering was not observed, most likely, as a result of higher thermodynamic stability of binary bromides CsCu(2)Br(3) and Cs(3)In(2)Br(9). The existence of three quasi-binary sections was observed, while no ternary bromide compounds were found.