Boron monosulfide: equation of state and pressure-induced phase transition

TL;DR

This study investigates the pressure-induced phase transition of boron monosulfide up to 50 GPa, revealing a new high-pressure phase with metallic properties and confirming experimental results with ab initio calculations.

Contribution

It provides the first detailed experimental and theoretical analysis of boron monosulfide's equation of state and high-pressure phase transition.

Findings

Formation of a new trigonal high-pressure phase above 35 GPa

High-pressure phase exhibits metallic behavior

Experimental bulk modulus aligns with ab initio calculations

Abstract

Quasi-hydrostatic compression of rhombohedral boron monosulfide (r-BS) has been studied up to 50 GPa at room temperature using diamond-anvil cells and angle-dispersive synchrotron X-ray diffraction. A fit of the experimental P-V data to the Vinet equation of state yields bulk modulus of 42.2(1.4) GPa and its first pressure derivative of 7.6(2) that are in excellent agreement with our ab initio calculations. Formation of a new high-pressure phase of boron monosulfide (hp-BS) has been observed above 35 GPa. According to ab initio evolutionary crystal structure predictions combined with Rietveld refinement of high-pressure X-ray diffraction data, the structure of hp-BS has trigonal symmetry and belongs to the space group P-3m1. As it follows from electron density of states calculations, the phase transformation is accompanied by an insulator-metal transition.