NEW SYNTHESES AND ELECTRIC CHARACTERIZATI ONS OF BARIUM COPPER TERNARY SULFIDES

The investigation of powder ternary sulfides BaCU4S3 (143) and BaCu2S2 (122) has been resumed. The synthesis of pure BaCu2S2 recently publis hed is confirmed as well as the structure established earlier from a s ingle crystal. Two new synthesis methods are used in order to prepare pure BaCu4S3. The powder diffraction pattern is quite similar to that simulated from previous crystallographic data. The electric resistance determined on pellets as a function of temperature shows a insulating behaviour in accordance with the electronic band structure calculatio ns which indicate a gap wider than 3 eV