Ferroelectricity Driven by Twisting of Silicate Tetrahedral Chains

TL;DR

This paper reports the discovery of ferroelectricity in a silicate compound, Bi2SiO5, driven by structural instability of silicate tetrahedral chains, offering a new approach to designing environmentally friendly ferroelectric materials.

Contribution

It introduces a novel ferroelectric material based on silicate tetrahedral chains, expanding the scope beyond traditional oxygen octahedral perovskites.

Findings

Ferroelectricity in Bi2SiO5 induced by a phase transition at ~673 K.

Polarization switching observed with a coercive field of 30 kV/cm.

First principles calculations estimate in-plane polarization at 23 μC/cm².

Abstract

Conventional perovskite-type ferroelectrics are based on octahedral units of oxygen, and often comprise toxic Pb to achieve robust ferroelectricity. Here, we report the ferroelectricity in a silicate-based compound, Bi2SiO5 (BSO), induced by a structural instability of the corresponding silicate tetrahedral chains. A low-energy phonon mode condenses at ~ 673 K to induce the proper ferroelectric phase transition. Polarization switching was observed in a BSO single crystal with a coercive field of 30 kV/cm and a spontaneous polarization of 0.3 microC/cm2 along a direction normal to the cleavage plane. The in-plane polarization was estimated by first principles calculations to be 23 microC/cm2. The present findings provide a new guideline for designing ferroelectric materials based on SiO4 tetrahedral units, which is ubiquitously found in natural minerals.