Effect of thermal processing on the microstructure and composition of Cu–Sb–Se compounds

We report on the effects of thermal processing on the microstructure and composition of a system with overall stoichiometry of 3Cu:1Sb:3Se with the aim of producing single-phase Cu 3 SbSe 3 . It was found that slow cooling from the melt produced a multiphase material consisting of Cu 2 Se and CuSbSe 2 , but devoid of Cu 3 SbSe 3 . Cooling rapidly from the melt resulted in three-phase microstructures consisting of Cu 2 Se, CuSbSe 2 , and Cu 3 SbSe 3 . Subsequent annealing of the three-phase material between 325 and 400 °C shifted the composition toward nearly pure Cu 3 SbSe 3 —the target compound of this work. The kinetics of the transformation into Cu 3 SbSe 3 was successfully described using a modified Avrami model which suggests that diffusion is the rate-controlling step. Values of Young’s modulus and hardness, obtained by nanoindentation, are reported for Cu 2 Se, CuSbSe 2 , and Cu 3 SbSe 3 .