Superhard boron suboxide (B6O): Crystal structure, synthesis, properties, applications, and materials based thereon

A review of reported data on the crystal structure, synthesis, and properties of boron suboxide B6O, which is a superhard material (hardness of up to 55 GPa, as measured in single crystals), and composites based on it is presented. Methods for the synthesis of B6O with a icosahedral structure and for the growing of crystals at high temperature and high pressure are described. The mechanical and operational characteristics of composite materials based on B6O are summarized; the resistance of B6O to oxidation is analyzed, and the properties of B6O–diamond and B6O–B4C composite materials are described.