Melting and decomposition of orthorhombic B6Si under high pressure. Issue 4 (1st October 2020) - Solozhenko, Vladimir L.
ABSTRACT: Melting of orthorhombic boron silicide B6 Si has been studied at pressures up to 8 GPa using in situ electrical resistivity measurements and quenching. It has been found that in the 2.6–7.7 GPa range B6 Si melts congruently, and the melting curve exhibits negative slope of −31(2) K/GPa that points to a higher density of the melt as compared to the solid phase. At very high temperatures B6 Si melt appears to be unstable and undergoes disproportionation into silicon and boron-rich silicides B n Si ( n ≥ 12). The onset temperature of disproportionation strongly depends on pressure, and the corresponding low-temperature boundary exhibits negative slope of −92(3) K/GPa which is indicative of significant volume decrease in the course of B6 Si melt decomposition.