Ternary compound B4CN4 prepared by direct nitridation of B4C

Borocarbide (B4C) can be directly nitrided to a stoichiometric ternary compound B4CN4 by heating in a stream of nitrogen gas at temperatures in a range of 1600–1900 °C. The reaction was diffusion-controlled with an activation energy of 242 kJ/mol. The resulting B4CN4 powder had the turbostratic layered boron nitride (t-BN) structure, which was changed into a three-dimensionally ordered layered structure (h-BN) with the lattice parameters of a = 2.506(1) Å and c = 6.710(9) Å on heating at 2250 °C in a closed nitrogen atmosphere. The a parameter is very close to that of h-BN, but the c parameter is larger than that of h-BN, rather close to that of graphite. The compound was reversibly decomposed to B4C + 2N2 on heating in Ar atmosphere at 2100 °C.