Convenient Route for the Synthesis of Transition-Metal Pnictides by Direct Reduction of Phosphate, Arsenate, and Antimonate Precursors

Abstract

Several transition-metal phosphates, arsenates, and antimonates undergo direct reduction in hydrogen at relatively low temperatures (400−1050 °C) to the corresponding phosphides, arsenides, and antimonides, providing a convenient route for the synthesis of transition-metal pnictides. We have synthesized by this route a variety of binary transition-metal phosphides (MoP, WP, Fe2P, Ni2P, FeP, RuP), arsenides (NiAs, CoAs), and antimonides (NiSb2, CoSb3). We could not however synthesize pnictides of manganese, vanadium, and gallium by this route, suggesting that the method is applicable only to those metals that are less electropositive than hydrogen, that is, those metals whose binary oxides are reducible by hydrogen to the metallic state.