Structural Distortions and Ferroelectricity in Antiperovskite Oxides with Tetrel Elements

TL;DR

This paper investigates the structural and electronic properties of antiperovskite oxides with tetrel elements using first principles calculations, revealing how structural trends and ferroelectricity can be predicted and induced in these materials.

Contribution

It introduces a predictive framework for the crystal structures of antiperovskite oxides and demonstrates how heterostructuring can induce ferroelectricity, expanding understanding beyond traditional perovskites.

Findings

Tolerance factor arguments can predict antiperovskite structures.

Heterostructuring induces ferroelectricity in antiperovskites.

Antiperovskites show unique electronic interactions not seen in perovskites.

Abstract

Antiperovskites share the same structure as perovskites, but allow completely different chemistries and nominal charge states of anions to be stabilized. This gives rise to many interesting phenomena, including septet superconductivity and topological crystalline insulating phases in these systems. Despite this, the work on the crystal structural trends in these compounds are more limited compared to perovskites. In this study, we consider the family of antiperovskite oxides with tetrel elements (Si, Ge, Sn, Pb) and alkaline earth metals (Ca, Sr, Ba), and perform a detailed study of their crystal structures using first principles density functional theory. We show how tolerance factor arguments can be constructed to predict their structure in a way parallel to the perovskites, and furthermore, how heterostructuring (or cation-order) can be used to induce ferroelectricity in these systems which may provide an experimental knob to modify electronic structure. We conclude by a discussion of the electronic structure of antiperovskites, and show that they display interesting trends not observed in regular perovskites, including significant antibonding interactions between face-center ions, which might need to be taken into account building effective electronic models of these compounds.