Structural features of boron nitride dense phase formation from rhombohedral modification under high static pressure

The real structure of boron nitride (BN) polycrystals after high-pressure treatment was investigated by x-ray and transmission electron microscopy methods. Different stages of boron nitride polycrystal evolution under high quasistatic pressure and high temperature were fixed, involving rhombohedral boron nitride twinning, one-dimensionally disordered structure, 2H, 4H, 3C dense phase formation and 3C-BN recrystallization. A new structural scheme of BN sub r -BN sub w transition is proposed.