Intrinsic and extrinsic nature of the giant piezoelectric effect in the initial poling of PMN-PT

R Grau-Crespo,S P Collins,S Grover,A G A Nisbet,P Finkel,F Fabrizi,T Hase,M G Cain,M Stewart,S C Vecchini

doi:10.1103/physrevmaterials.5.l120601

Abstract

Demonstrating both the intrinsic and extrinsic nature of the giant piezoelectric effect (GPE) in complex solid solutions, near the morphotropic phase boundary, has been extremely challenging until now, because such materials exhibit multiple phases on the order of tens of microns across, meaning important information is lost due to averaging when using established high resolution diffraction techniques to extract three dimensional structural information. We have used a different approach proposed by Nisbet et al. [Acta Crystallogr. Sect. A 71, 20 (2015)], which has been adapted to differentiate between spatially adjacent phases and simultaneously track the evolution of those phases in response to electric fields. As a result, we have identified three environment specific GPEs. The first of these is a GPE which is an order of magnitude greater than previously reported for a given change in field. This is observed during a tetragonal-monoclinic transition in a multiphasic environment. A secondary, large GPE is observed in the neighboring, nontransitioning, monoclinic phase due to stress biasing, and a more typical GPE is observed when the system becomes monophasic. Our results demonstrate the simultaneous and complex interplay of intrinsic and extrinsic factors contributing to the GPE which is likely to have implications for device manufacture and miniaturization.

Highlights

Lattice changes were most pronounced through the transition from a tetragonal phase to a monoclinic phase with the largest strain being in the a direction with a change of 0.52%
We did not observe this level of strain macroscopically in our previous work for such low electric fields [17] and it is likely a localized phenomenon facilitated by a localized stress bias as the system tends towards a single phase
It does hint at what might be possible with the appropriate materials engineering and suggests the potential for reducing the material required for piezoelectric effect transistors (PETs) devices

Summary

Introduction

A scale referenced probe capable of tracking the evolution of phases as a function of time, temperature, in situ electric field, stress, and other technologically important parameters while sampling a fixed sample volume without averaging is required. A region consisting of two phases indicated by two sets of lines was selected with the goal of observing the behavior of two polymorphs as a function of an applied electric field.

Results

Conclusion