Optimizing K0.5Na0.5NbO3 Single Crystal by Engineering Piezoelectric Anisotropy.

Weixiong Li,Guangzhong Xie,Chunxu Chen,Yuanjie Su

doi:10.3390/nano11071753

Weixiong Li, Guangzhong Xie + Show 2 more

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https://doi.org/10.3390/nano11071753

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Abstract

K0.5Na0.5NbO3 is considered as one of the most promising lead-free piezoelectric ceramics in the field of wearable electronics because of its excellent piezoelectric properties and environmental friendliness. In this work, the temperature-dependent longitudinal piezoelectric coefficient was investigated in K0.5Na0.5NbO3 single crystals via the Landau–Ginzburg–Devonshire theory. Results show that the piezoelectric anisotropy varies with the temperature and the maximum of deviates from the polar direction of the ferroelectric phase. In the tetragonal phase, parallels with cubic polarization direction near the tetragonal-cubic transition region, and then gradually switches toward the nonpolar direction with decreasing temperatures. The maximum of in the orthorhombic phase reveals a distinct varying trend in different crystal planes. As for the rhombohedral phase, slight fluctuation of the maximum of was observed and delivered a more stable temperature-dependent maximum and its corresponding angle θmax in comparison with tetragonal and orthorhombic phases. This work not only sheds some light on the temperature-dependent phase transitions, but also paves the way for the optimization of piezoelectric properties in piezoelectric materials and devices.

Highlights

This work sheds some light on the temperaturedependent phase transitions, and paves the way for the optimization of piezoelectric properties in piezoelectric materials and devices
Pb(Zrx Ti1−x )O3 (PZT) [5] and Pb(Mg,Nb)O3 (PMN) [6] ceramics, possess huge piezoelectric properties but cause severe environmental and health concerns owing to their toxicity
The main purpose of this work is to study the piezoelectric anisotropy of K0.5 Na0.5 NbO3 single crystals as a function of temperature and to unravel the impact of phase transitions on the orientation and amplitude of the longitudinal piezoelectric coefficient

Summary

Introduction

Academic Editor: Seok Woo Lee. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. With the gradual deepening and prosperity of the smart wearable industry revolution, piezoelectric-based flexible electronics have attracted considerable attention because of their promising applications in robotics [1], human–machine interaction (HMI) [2], energy harvesters [3], and internet of things (IOT) [4]. Pb(Zrx Ti1−x )O3 (PZT) [5] and Pb(Mg,Nb)O3 (PMN) [6] ceramics, possess huge piezoelectric properties but cause severe environmental and health concerns owing to their toxicity

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