Spontaneous Growth of CaBi4Ti4O15 Piezoelectric Crystal Using Mixed Flux Agents

Mengdi Fan,Xian Zhao,Lili Li,Xiufeng Cheng,Fapeng Yu,Guangda Wu,Yanlu Li

doi:10.3390/cryst10080698

Abstract

The bismuth layer-structured ferroelectrics (BLSFs) materials have potential for high-temperature piezoelectric applications. Among these piezoelectric materials, the CaBi4Ti4O15 (CBT) piezoelectric ceramic with a high decomposition temperature of about 1250 °C attracts a lot of attention. Achieving a CBT single crystal is a significant way to improve its piezoelectric properties. For this purpose, the flux system for growing CBT crystal was explored in this study. The optimum flux composition ratio was found to be PbO:B2O3:CBT = 3:3:1 in mol%, where the PbO–B2O3 mixtures were used as a flux system. Millimeter size flake-shaped CBT crystals were obtained using the spontaneous growth process for the first time. The relationship between the crystal structure and flake growth habit was analyzed. In addition, the bandgap was evaluated by the combination of transmittance spectrum and first-principle calculations. Besides, the piezoelectric property was predicted from the perspective of polyhedral distortion, which indicated the potential of CBT crystal for piezoelectric applications.

Highlights

Since the discovery of the piezoelectric effect, piezoelectric materials have been widely explored as sensors, transducers, actuators, energy harvesting devices, etc
Prior to single crystal growth, the CaBi4 Ti4 O15 polycrystalline compound was synthesized by a solid-state reaction method
According to the principle of selecting the flux agent, we studied the fluxing behaviors of two kinds of flux systems for crystallizing CBT crystal, i.e., Bi2 O3 and PbO–B2O3 flux agents (PbO)–B2 O3 flux systems

Summary

Introduction

Since the discovery of the piezoelectric effect, piezoelectric materials have been widely explored as sensors, transducers, actuators, energy harvesting devices, etc. Piezoelectric materials that can maintain the electromechanical and piezoelectric properties at high temperatures and even harsh environments are needed, especially in aerospace industries, oil exploitation, and power plant fields [1,2,3]. The ever-increasing demands on operational temperature have stimulated a great deal of research effort on exploring piezoelectric materials with a high curie temperature (TC ) or high melting point, prior to which the electromechanical and piezoelectric properties should be maintained. Several kinds of piezoelectric crystals with high melting points have been studied as the candidates for high-temperature piezoelectric applications [4,5,6]. The RECa4 O(BO3 ) (ReCOB) crystals with good temperature stability and high electrical resistivity were studied for high-temperature vibration sensing applications [6].

Methods

Results

Conclusion