First-principles study of (BiScO3){1-x}-(PbTiO3){x} piezoelectric alloys

TL;DR

This study uses first-principles calculations to analyze the structural, ferroelectric, and piezoelectric properties of (BiScO3)_{1-x}-(PbTiO3)_x alloys, revealing their potential advantages over existing materials for piezoelectric applications.

Contribution

It provides the first-principles analysis of BS-PT alloys, highlighting their large distortions, polarization, and comparable piezoelectric response to PZT, with insights into the underlying hybridization mechanisms.

Findings

BS-PT exhibits large structural distortions and polarization at the MPB.

Hybridization between Bi/Pb-6p and O-2p orbitals dominates properties.

Piezoelectric responses of BS-PT are comparable to PZT at the MPB.

Abstract

We report a first-principles study of a class of (BiScO3)_{1-x}-(PbTiO3)_x (BS-PT) alloys recently proposed by Eitel et al. as promising materials for piezoelectric actuator applications. We show that (i) BS-PT displays very large structural distortions and polarizations at the morphotropic phase boundary (MPB) (we obtain a c/a of ~1.05-1.08 and P_tet of ~1.1 C/m^2); (ii) the ferroelectric and piezoelectric properties of BS-PT are dominated by the onset of hybridization between Bi/Pb-6p and O-2p orbitals, a mechanism that is enhanced upon substitution of Pb by Bi; and (iii) the piezoelectric responses of BS-PT and Pb(Zr_{1-x}Ti_x)O3 (PZT) at the MPB are comparable, at least as far as the computed values of the piezoelectric coefficient d_15 are concerned. While our results are generally consistent with experiment, they also suggest that certain intrinsic properties of BS-PT may be even better than has been indicated by experiments to date. We also discuss results for PZT that demonstrate the prominent role played by Pb displacements in its piezoelectric properties.