Synthesis of Boron Nitride by Self‐Propagating Reactions at High Pressure

Peculiarities of the formation of BN in a self‐propagating reaction between LiBF 4 and Li 3 N have been studied under a wide range of p,T conditions within the region of thermodynamic stability of cBN. Boron nitride crystallized mainly in the form of highly ordered hBN (1700–2100 K), of mesographitic BN (2200–3000 K), or of turbostratic BN (>3000 K). Cubic boron nitride was obtained with a low yield (up to 14 vol%) as a result of precipitation from the metastable eutectic liquid in the BN‐Li 3 N system. These results give further evidence for an alternative metastable behavior in the BN phase formation under high pressures.