Process for preparing rhombohedral system boron nitride using NaBH.sub.4 - and NH.sub.4 Cl

摘要

A process for preparing rhombohedral system boron nitride, which comprises mixing NaBH.sub.4 with at least an equimolar amount of NH. sub.4 Cl, and heating the resulting mixture in a non-oxidizing atmosphere at a temperature of at least 750° C. and lower than 1000° C. for at least 3 hours.