Synthesis, conductivity and high-pressure phase transition of amorphous boron carbon nitride

摘要

Amorphous BCN was prepared by chemical solid-state reaction between boracic acid (H3BO3) and melamine (C3N6H6) in mass ratios of H3BO3 to C3N6H6 of 1:2-1:4 and heat treatment at 1273 K under 10(-3) Pa. The amorphous B-C-N behave insulating property below 890 K, but semiconductor conductivity above 890 K and show different conductivity-temperature relationships in temperature ranges of 913-963 and 963-1083K. The conductive activation energy was calculated to be 0.26-0.34eV at 913-963K and 1.02-1.10eV at 963-1083 K, implying that the conduction mechanisms are different in the different temperature ranges. Annealed for 40 min at 1473 K under 4.0 GPa, the amorphous BCN with the chemical composition B0.48C0.29N0.23 was prepared in the mass ratio of 1:3 crystallizes into single-phase hexagonal (h-BCN) compound with lattice constants of a = 0.2506 nm and c = 0.6652 nm. Raman scattering peaks were observed at 1330, 1364,1584 and 1617 cm(-1) in the Raman spectrum (RS) of h-BCN, of which the peaks located at 1330 and 1617 cm(-1) are assigned to characteristic peaks of the h-BCN. (c) 2007 Elsevier B.V. All rights reserved.