科研之友
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摘要
Using the ab initio particle swarm optimization algorithm for crystal structure prediction, we have predicted an orthorhombic Pmmn structure for OsB4, which is energetically much superior to the previously proposed WB4-type structure. The Pmmn structure consists of irregular OsB10 dodecahedrons connected by edges and is stable against decompression into a mixture of Os and B at ambient pressure. OsB4 within this orthorhombic phase is found to be an ultra-incompressible and hard material due to its high, bulk modulus (294 GPa) and large hardness (28 GPa), originating from the strong and directional covalent B-B and B-Os bonds.
