Phase diagram of the B-BN system at pressures up to 24 GPa: Experimental study and thermodynamic analysis

Abstract

Phase relations in the B-BN system have been studied ex situ and in situ at pressures 2-20 GPa and temperatures up to 2800 K. The evolution of topology of the B-BN phase diagram has been investigated up to 24 GPa using models of phenomenological thermodynamics with interaction parameters derived from our experimental data on phase equilibria at high pressures and high temperatures. There are two thermodynamically stable boron subnitrides in the system i.e. B13N2 and B50N2. Above 16.5 GPa the B50N2 = L + B13N2 peritectic reaction transforms to the solid-phase reaction of B50N2 decomposition into tetragonal boron (t'-B52) and B13N2, while the incongruent type of B13N2 melting changes to the congruent type only above 23.5 GPa. The constructed phase diagram provides fundamentals for directed high-pressure synthesis of superhard phases in the B-BN system.

References in corpus (6)

• On melting of B4C boron carbide under pressure
• Mechanical properties of superhard boron subnitride B13N2
• Structure and equation of state of tetragonal boron subnitride B50N2
• On electrical conductivity of melts of boron and its compounds under pressure
• On melting of boron subnitride B13N2 under pressure
• Thermal expansion of boron subnitrides

Cited by in corpus (3)

• High-pressure synthesis of superhard and ultrahard materials
• First principles investigations of electronic and magnetic properties of new rh.-B12N3
• First-principles studies of the electronic and magnetic structures and bonding properties of boron subnitride B${}_{13}$N${}_2$