Discovery of new boron-rich chalcogenides: orthorhombic B6X (X = S, Se)

TL;DR

This study reports the discovery and characterization of new boron-rich chalcogenides B6S and B6Se, synthesized under high pressure and temperature, with detailed structural, vibrational, and mechanical property analyses.

Contribution

It introduces two new orthorhombic boron-rich chalcogenides and provides their structural, vibrational, and mechanical properties using experimental and computational methods.

Findings

Both compounds have orthorhombic Pmna symmetry.

Raman spectra match theoretical phonon modes.

Predicted hardness around 31 GPa, indicating they are hard materials.

Abstract

New boron-rich sulfide B6S and selenide B6Se have been discovered from high pressure - high temperature synthesis combined with ab initio evolutionary crystal structure prediction, and studied by synchrotron X-ray diffraction and Raman spectroscopy at ambient conditions. As it follows from Rietveld refinement of powder X-ray diffraction data, both chalcogenides have orthorhombic symmetry and belongs to Pmna space group. All experimentally observed Raman bands have been attributed to the theoretically calculated phonon modes, and the mode assignment has been performed. Prediction of mechanical properties (hardness and elastic moduli) of new boron-rich chalcogenides have been made using ab initio routines, and both compounds were found to be members of a family of hard phases (Hv ~ 31 GPa).