Experimental and Ab-initio Investigations of Osmium Diboride

More than half a century after their discovery, almost nothing is known about the physical properties of osmium borides, thought their structures have been clearly identified in the early sixties. We re-examined the phase diagram of the binary system osmium-boron and confirm the existence of two hexagonal phases, OsB1.1, Os2B3 and an orthorhombic phase, OsB2. Our microhardness measurements show that the synthesized OsB2 is extremely hard. In addition, first-principles calculations have been conducted to investigate its physical properties. It is shown that OsB2 is also a low compressibility material. Most of the transition metal borides have already found applications as in protective armor, nuclear reactors, reinforcement, etc. OsB2 can be used in applications like hard coating.