Thermal expansion of boron subnitrides

Abstract The lattice parameters of two boron subnitrides, B 13 N 2 and B 50 N 2 , have been measured as a function of temperature between 298 and 1273 K, and the corresponding thermal expansion coefficients have been determined. Thermal expansion of both boron subnitrides was found to be quasi-linear, and the volume thermal expansion coefficients of B 50 N 2 (15.7 (2) × 10 −6  K −1 ) and B 13 N 2 (21.3 (2) × 10 −6  K −1 ) are of the same order of magnitude as those of boron-rich compounds with structure related to α-rhombohedral boron. For both boron subnitrides no temperature-induced phase transitions have been observed in the temperature range under study.