Boron Nitride with Sphalerite Structure P-BN

2 Diamond-Like Boron Nitride Modifications Cubic Boron Nitride with Sphalerite Structure (P-BN) 

The field of transformation of other BN phases (i.e., a-BN Including rhombohedral and turbostratic BN, y-BN) into cubic boron nitride (P-BN) has been the subject of numerous reviews within the past four years. Perhaps the most comprehensive review of p-BN formation, structure, and properties was compiled by Rapoport [1]. Another review is given in English [2], and there are reviews in French [3], Japanese [4 to 8], Russian [9 to 12], and German [13]. In 

The kinetics of spontaneous crystallization of p-BN (at 2000 K and 4.8 GPa) and the effect of nucleation by admixed small p-BN particles (up to 2300 K, 70 kbar) have been studied [15 to 20]. The rate of direct a-BNp-BN transformation increases towards higher temperatures, and the effect of added crystallization centers is lessened see also [21]. 

While the direct conversion of a-BN to p-BN is of high interest for the preparation of p-BN semiconductors, large scale production of p-BN is performed by catalyst-aided procedures under careful control of the amount of the catalyst [36]. The catalyst material has to be removed after the end of the phase transformation process by treatment with base (sometimes acid) in order to dissolve unreacted a-BN and the catalysts, since they are not included in the lattice of the resultant p-BN. Under the high pressure and temperatures required for the phase transformation, the catalysts and their reaction products with boron nitride form a melt from which p-BN crystallizes. The temperature for the process is lowered by eutectic formation between the catalyst and BN (see discussion by [1]). 

Akaishi, M. Fukunaga, 0. Kawasaki, T. Tanji, H. Denki Kagaku Kogyo K.K. (Japan Kokai Tokkyo Koho 62-108712 [1987] from C.A. 107 [1987] No. 63686). 

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