Synthesis of osmium borides by mechanochemical method

Abstract

AbstractTransition metal osmium borides were synthesized by mechanochemical method using high‐energy ball‐milling with Os (Osmium) and B (Boron) powders as raw materials. The formation process, reaction mechanism, and thermal stability of the mechochemically synthesized osmium borides were studied. Almost pure Os2B3 phase was obtained when the Os‐to‐B molar ratio was 1:2; while ReB2‐type hexagonal OsB2 with a small amount of RuB2‐type orthorhombic OsB2 was obtained when the Os‐to‐B molar ratio was 1:3. Stoichiometry OsB2 was obtained from boron rich starting mixture powders due to the B loss during the high‐energy ball‐milling process. It was also found that WC and osmium oxide were present as contaminants after ball milling for 40 hours. Heat treatment results revealed that the as‐synthesized Os2B3 powders are thermally stable in flowing Ar up to 800°C, but a transformation from hexagonal to orthorhombic structure partially occurred for the OsB2 powders as low as 600°C.