LATTICE-PARAMETERS OF BORON-NITRIDE POLYMORPHOUS MODIFICATIONS AS A FUNCTION OF THEIR CRYSTAL-STRUCTURE PERFECTION

The data available in the literature on the lattice parameters of boro n nitride (BN) polymorphic modifications have been analysed. A precise measurement of interplanar spacing has been carried out for hexagonal BN of different degrees of crystalline perfection and rhombohedral BN . The possibilities for alteration of wurtzitic BN lattice parameters have been studied. The results obtained have been used to establish th e fundamental reference values of lattice parameters for all crystalli ne modifications of BN.