Preparation of cubic BN c-BN is prepared analogously to the preparation of synthetic diamond from graphite. Direct conversion of hexagonal boron nitride to the cubic form has been observed at pressures between 5 and 18 GPa and temperatures between 1730 and 3230 °C, that is similar parameters as for direct graphite-diamond conversion. The addition of a small amount of boron oxide can lower the required pressure to 4–7 GPa and temperature to 1500 °C. As in diamond synthesis, to further reduce the conversion pressures and temperatures, a catalyst is added, such as lithium, potassium, or magnesium, their nitrides, their fluoronitrides, water with ammonium compounds, or hydrazine. Other industrial synthesis methods, again borrowed from diamond growth, use crystal growth in a temperature gradient, or explosive shock wave. The shock wave method is used to produce material called heterodiamond, a superhard compound of boron, carbon, and nitrogen.
preparation of cubic bn c-bn is prepared analogously to the preparation of synthetic diamond from graphite direct conversion of hexagonal boron nitride to the cubic form has been observed at pressures between 5 and 18 gpa and temperatures between 1730 and 3230 °c that is similar parameters as for direct graphite-diamond conversion the addition of a small amount of boron oxide can lower the required pressure to 4–7 gpa and temperature to 1500 °c as in diamond synthesis to further reduce the conversion pressures and temperatures a catalyst is added such as lithium potassium or magnesium their nitrides their fluoronitrides water with ammonium compounds or hydrazine other industrial synthesis methods again borrowed from diamond growth use crystal growth in a temperature gradient or explosive shock wave the shock wave method is used to produce material called heterodiamond a superhard compound of boron carbon and nitrogen