Ferroelectric 2D Antimony Oxides with Wide Bandgaps

TL;DR

This paper predicts two new 2D antimony oxide polymorphs with ferroelectric properties and wide bandgaps, using computational methods, highlighting their potential for ferroelectric devices and applications.

Contribution

First prediction of 2D ferroelectric antimony oxides with detailed electronic and ferroelectric properties using evolutionary algorithms and DFT calculations.

Findings

Out-of-plane ferroelectricity in γ-Sb₂O₄

In-plane ferroelectricity in δ-Sb₂O₄

Large band gaps of 5.51 eV and 3.39 eV for the two phases

Abstract

The first two-dimensional (2D) polymorphs of antimony dioxide, namely, $\gamma$-Sb$_2$O$_4$ and $\delta$-Sb$_2$O$_4$, are predicted using the evolutionary algorithm combined with first-principles density functional theory (DFT) calculations. Out-of-plane ferroelectricity is found in $\gamma$-Sb$_2$O$_4$, while in-plane ferroelectricity is found in $\delta$-Sb$_2$O$_4$. The predicted dipole moments of $\gamma$-Sb$_2$O$_4$ and $\delta$-Sb$_2$O$_4$ phases are 36.63 and 14.96 e\r{A}, respectively, implying that they can be good candidates for making ferroelectric devices. The calculations show that doping with other group V elements or applying strain can lower the switching energy barriers and thus facilitate switching. Results from GW calculations show indirect band gaps of 5.51 and 3.39 eV for $\gamma$-Sb$_2$O$_4$ and $\delta$-Sb$_2$O$_4$ in their monolayers, respectively. Raman spectra are calculated to facilitate the experimental investigation of the predicted structures. The existence of both in-plane and out-of-plane 2D ferroelectricity and the large band gaps make this material system particularly interesting for potential applications.