Growth of Ca-germanide and Ca-silicide crystals by mechanical alloying

Abstract

Ca-germanide and Ca-silicide crystals were synthesized by mechanical alloying (MA). The resulting powders made from the Ca and Si powders contain Ca2Si and/or Ca5Si3 phases with additional cubic phase crystals. The grown phases, namely Ca2Si and Ca 5Si3, can be controlled by the Ca/Si ratio and the Si powder size. For the powders synthesized using the Ca and Ge powders, the cubic crystalline phase was synthesized. It was found that the powders synthesized from the Ca and Ge powders are covered by an amorphous layer that contains oxidized carbons. The Ca-based bulk tablets pressed from the powders show a p-type semiconducting behavior, though the powder surface is heavily oxidized, which might affect the transport property of the bulk. © 2009 The Surface Science Society of Japan.