First principles studies of SnTiO3 perovskite as a potential ferroelectric material

TL;DR

This study uses first principles calculations to explore SnTiO3 as a lead-free ferroelectric material, revealing its stable tetragonal structure, polarization properties, and bonding characteristics compared to PbTiO3.

Contribution

It provides the first detailed first-principles analysis of SnTiO3's structure, polarization, and electronic bonding, highlighting its potential as an environmentally friendly ferroelectric.

Findings

SnTiO3 has a stable tetragonal structure.

SnTiO3 exhibits higher polarization than PbTiO3.

SnTiO3 shows stronger covalent bonding with oxygen.

Abstract

In the context of the search for environment-respectful, lead- and bismuth- free chemical compounds for devices such as actuators, SnTiO3 (ST) is investigated from first principles within DFT. Full geometry optimization provides a stable tetragonal structure relative to cubic one. From the equation of state the equilibrium volume of SnTiO3 is found smaller than ferroelectric PbTiO3 (PT) in agreement with a smaller Sn2+ radius. While ionic displacements exhibit similar trends between ST and PT a larger tetragonality (c/a ratio) for ST results in a larger polarization, PST = 1.1 C.m2. The analysis of the electronic band structure detailing the Sn-O and Ti-O interactions points to a differentiated chemical bonding and a reinforcement of the covalent bonding with respect to Pb homologue.