Synthesis of boron suboxide from boron and boric acid under mild pressure and temperature conditions

Boron suboxide (B6O) was synthesized by reacting boron and boric acid (H3BO3) at pressures between 1 and 10 GPa, and at temperatures between 1300 and 1400 °C. The B6O samples prepared were icosahedral with diameters ranging from 20 to 300 nm. Well-crystallized and icosahedral crystals with an average size of ∼100 nm can be obtained at milder reaction conditions (1 GPa and 1300 °C for 2 h) as compared to previous work. The bulk B6O sample was stable in air at 600 °C and then slowly oxidized up to 1000 °C. The relatively mild synthetic conditions developed in this study provide a more practical synthesis of B6O, which may potentially be used as a substitute for diamond in industry as a new superhard material.