Solid-state chemistry of glassy antimony oxides

TL;DR

This study uses ab initio molecular dynamics to explore the atomic and electronic structures of amorphous antimony oxides at various oxidation states, revealing structural similarities to crystalline phases and electronic properties that vary with oxidation level.

Contribution

It provides the first detailed computational analysis of amorphous antimony oxides across different oxidation states, including phase diagrams and electronic structure insights.

Findings

Amorphous Sb2O3 resembles the β-phase of crystalline antimony trioxide.

Higher oxidation levels lead to a narrowing of the electronic band gap.

The phase diagram shows stability variations with oxygen chemical potential.

Abstract

The amorphous phases of antimony oxide at three different oxidation levels have been investigated by {\it ab initio} molecular-dynamics calculations using a simulated `melt-quench' approach. The atomic and electronic structure of the amorphous phases are analyzed and compared to their crystalline counterparts. The amorphous structure of the trioxide ({\it a\,}--Sb$_2$O$_3$) resembles the $\beta$-phase of the crystalline form (valentinite), in agreement with previous observations. In the relaxed athermal structure, however, more senarmontite-like structural features are apparent. The phase diagram of the amorphous phases with respect to oxygen chemical potential has been calculated within the framework of {\it ab initio} thermodynamics. At elevated oxidation levels, the resulting tetraoxide and pentoxide materials show distinct variation in electronic structure compared to the trioxide, with the electronic density of states indicating a narrowing of the electronic gap with increasing oxidation level.