Synthesis and structural properties of CuInGeS4

The synthesis of the CuInGeS4 compound was performed in a shaft-type furnace by the single-temperature method realized by the gradual heating of the samples (heating rate of 10 K/h) to 1370 K with an intermediate exposure to 820 K for 36 h. The annealing was performed at 670 K for 250 h. The synthesis process was finished after quenching the samples into cold water.The phase diagram of the CuInS2–GeS2 system was investigated using XRD, differential thermal and microstructure analyses. Two different processes take place in the system, a peritectic one, with the peritectic point coordinates 75 mol% GeS2, 1108 K, and a eutectic one at 86 mol% GeS2, 1033 K.The crystal structure of CuInGeS4 was studied by the powder method. The compound crystallizes in the tetragonal symmetry, space group I-4 (structural type CdGa2S4), with the lattice parameters a=0.55492(2) nm, c=1.00282(6) nm. Atomic parameters were calculated in the anisotropic approximation, with RI=0.0680 and RP=0.1315.