CRYSTAL-STRUCTURE AND ELECTRICAL-CONDUCTIVITY OF GA1.78CR0.89S4

The crystal structure of Ga//1//. //7//8Cr//0//. //8//9S//4 has been determined from single crystal X-ray diffraction data and refined to R equals 0. 026. It crystallizes trigonally in a defect variant of the FeGa//2S//4-type with the space group P3ml with z equals 1 and lattice constants a equals 360. 43 (2) and c equals 1194. 86 (2) pm with Ga atoms occupying the tetrahedral sites and Cr atoms the octahedral sites. The electrical conductivity of Ga//1//. //7//8Cr//0//. //8//9S//4 measured on powder samples is about 7. 10** minus **5 ohm** minus **1 cm** minus **1 at 400 degree C with an activation energy for conduction of 1. 2eV.