Synthesis Of Crystalline BCN Compounds Under High Pressure And High Temperature And Their Thermal Expansion Property

In this contribution, B2CN compound was prepared by mechanical millingprocess using B, h-BN and graphite as starting materials. Then hexagonal and cubic BCN compounds were synthesized by HPHTtreatment. XRD, EDX, SEM and FTIR were used to characterize the structure,composition, morphology and chemical bonds of the samples. HT- XRD wasused to measure the liner thermal expansion coefficients of the samples Hexagonal B2CN phase was obtained after a treatment of the B2CNcompound under the pressure of 4~6 GPa at the temperature range of1000~1600 ℃. With the assistance of Ca3B2N4 catalyst, cubic B0.54C0.12N0.34was synthesized under the pressure of 5.5~6 GPa at the temperature range of1200~1600 ℃. In vacuum, the thermal expansion coefficients of hexagonalBCN phase are αa= -8.423×10-6 K–1 (20 ~500 ℃), αa=0 (500~1200 ℃), αc=1.136×10-6 K–1 (20~1200 ℃); The thermal expansion coefficients of cubicBCN phase is α=5.4×10-6 K–1 (20~ 1200 ℃).