Impact of Phase Structure on Piezoelectric Properties of Textured Lead-Free Ceramics

Xiaoyi Gao,Hua Hao,Hanxing Liu,Qinghu Guo,Shujun Zhang,Fangquan Xia,Nannan Dong

doi:10.3390/cryst10050367

Xiaoyi Gao, Hua Hao + Show 5 more

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https://doi.org/10.3390/cryst10050367

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Abstract

The impact of phase structure on piezoelectric performances of <001> textured Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics was studied, including 0.88NBT-0.08K0.5Bi0.5TiO3-0.04BaTiO3 (88NBT) with morphotropic phase boundary (MPB) composition and 0.90NBT-0.07K0.5Bi0.5TiO3-0.03BaTiO3 (90NBT) with rhombohedral phase. Both textured ceramics exhibit a high Lotgering factor, being on the order of f~96%. The piezoelectric coefficients of the textured 88NBT and 90NBT ceramics are increased by 20% and 60%, respectively, comparing to their randomly oriented ceramics. The piezoelectric enhancement of 90NBT textured ceramic is three times higher than 88NBT, revealing the phase structure plays a significant role in enhancing the piezoelectric performances of textured ceramics. Of particular significance is that the 90NBT textured ceramic exhibits almost hysteresis-free strain behavior. The enhanced piezoelectric property with minimal strain hysteresis is attributed to the <001> poled rhombohedral engineered domain configuration.

Highlights

In recent years, lead-free piezoelectric materials based on Na0.5 Bi0.5 TiO3 (NBT) have attracted extensive attention, which is considered to be a potential candidate due to their good ferroelectric and piezoelectric properties, with high Curie temperature TC of 320 ◦ C and large remnant polarizationPr value of 38 μC/cm2 [1]
Based on the X-ray diffraction (XRD) results, the Lotgering 3 of 10 factor (f) of the textured ceramics can be estimated by Lotgering equations [27]
-textured 88NBT (MPB) and 90NBT ceramics with Lotgering factor f~96% were prepared via the template grain growth method (TGG) method

Summary

Introduction

Lead-free piezoelectric materials based on Na0.5 Bi0.5 TiO3 (NBT) have attracted extensive attention, which is considered to be a potential candidate due to their good ferroelectric and piezoelectric properties, with high Curie temperature TC of 320 ◦ C and large remnant polarizationPr value of 38 μC/cm2 [1]. Lead-free piezoelectric materials based on Na0.5 Bi0.5 TiO3 (NBT) have attracted extensive attention, which is considered to be a potential candidate due to their good ferroelectric and piezoelectric properties, with high Curie temperature TC of 320 ◦ C and large remnant polarization. There is still a need to enhance the properties of NBT-based ceramics before they can replace lead-based materials. Na0.5 Bi0.5 TiO3 -SrTiO3 (NBT-ST), Na0.5 Bi0.5 TiO3 -BaTiO3 (NBT-BT), Na0.5 Bi0.5 TiO3 -K0.5 Bi0.5 TiO3 -BaTiO3. It is difficult to increase the piezoelectric performances of NBT-based binary and ternary polycrystalline ceramics further by only composition tuning. Texturing is a promising approach to enhance the piezoelectric performances of ferroelectric ceramics via controlling the microstructure without drastically changing the Crystals 2020, 10, 367; doi:10.3390/cryst10050367 www.mdpi.com/journal/crystals. Crystals 2020, 10, 367 composition [9,10,11] taking advantage of grain alignment along ab specific crystallographic direction, showing unique anisotropic behavior, being analogous to domain engineering reported in ferroelectric single crystals [12,13,14,15].

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