HIGH-PRESSURE SYNTHESIS AND ELECTRICAL-PROPERTIES OF MN3GE5 WITH MN11SI19-TYPE STRUCTURE

The new germanium-rich manganese germanide, Mn//3Ge//5, was synthesized at 600-1000 degree C and 4 GPa using a Belt-type apparatus. The crystal structure of Mn//3Ge//5 was identified as possessing the Mn//1//1Si//1//9 type with a tetragonal cell (Schoenfies symbol D//2//d). The electrical resistivity of Mn//3Ge//5 increased with increasing temperature and saturated above 200 K. The thermoelectric power was 50-70 mu V/K and its sign was positive. These data indicated that Mn//3Ge//5 was a p-type semiconductor or a semimetal.