Investigation of the Structural, Electronic and Mechanical Properties of Type-VIII Ba8Si46 Clathrate under High-Pressure through First-Principles

Abstract

By means of density functional theory (DFT) calculations, we have investigated the effect of hydrostatic pressure on the structural, electronic and elastic properties of the barium-doped silicon clathrate Ba8Si46 in the type-VIII structure (phase). Physical properties are calculated under different conditions of pressure (0 GPa to 45 GPa) using the GGA-PBE functional, those calculations have been performed using the Cambridge serial total energy package CASTEP code within the Materials Studio package. Electronic properties have shown that the type-VIII Ba8Si46 has metal-like properties with a fundamental bandgap of 1 eV. Under pressure the fundamental bandgap increases slightly and the positions of the valence band maximum VBM and the conduction band minimum CBM remain unchanged. We found that the compound is mechanically stable under the pressure range, but this needs to be confirmed experimentally through synthesis, a comparison with the type-I and the guest-free counterparts has exhibited promising features for the type-VIII Ba8Si46. I.

Investigation on the Stability, Elastic Properties, and Electronic Structure of Mg2Si Doped with Different Concentrations of Cu: A First‐Principles Calculation

“…[22][23][24] The general gradient approximation (GGA þ U) with the Perdew-Burke-Ernzerhof (PBE) approach was selected to estimate the exchange and correlation energy. [25] The cut-off energy of plane wave is set to 400 eV, the reciprocal space is k-point space of 0.05 nm À1 , and the Brillouin zone is sampled by means of the Monkhorst-Pack [26] k-point grid. In the process of structural optimization, a 9 Â 9 Â 9 k-point grid division was adopted in the Brillouin region, and an 11 Â 11 Â 11 k-point grid division was adopted in the static calculation, elastic calculation, and electronic property calculation.…”

First-principles investigation of the ultra-wide band gap halides perovskite XBeF3 (X = Na, K) with pressure effects

“…From table 3, the B/G values of NaBeF 3 are 2.0167, 2.0563, 2.0947 and 2.1410 at 0, 10, 20 and 30 GPa, respectively, indicating that the ductility of NaBeF 3 crystal increases with increasing pressure in this pressure range, which is also same for KBeF 3 . For cubic crystals, their mechanical stability at high pressure is determined by the following conditions [41]:…”

A Borosilicide with Clathrate VIII Structure

“…22 Interestingly, the off-centering of the cage atom is a feature observed for all clathrate VIII type structures, even for the optimized hypothetical binary Ba 8 Si 46 . 27 The magnitude of the off-center displacement can be attributed to the extent of the respective ionic interaction. Depending on the synthesis pressure (5−8 GPa), the lattice parameter of clathrate VIII Na 8 B x Si 46−x varies from a = 9.7579(6) to 9.6750(4) Å.…”

“…Interestingly, the off-centering of the cage atom is a feature observed for all clathrate VIII type structures, even for the optimized hypothetical binary Ba 8 Si 46 . The magnitude of the off-center displacement can be attributed to the extent of the respective ionic interaction.…”