Transport and Electromechanical Properties of Ca3TaGa3Si2O14 Piezoelectric Crystals at Extreme Temperatures

Yuriy Suhak,Hagen Schmidt,Ward L Johnson,Holger Fritze,Andrei Sotnikov

doi:10.1557/adv.2019.16

Abstract

Transport mechanisms in structurally ordered piezoelectric Ca3TaGa3Si2O14 (CTGS) single crystals are studied in the temperature range of 1000-1300 °C by application of the isotope 18O as a tracer and subsequent analysis of diffusion profiles of this isotope using secondary ion mass spectrometry (SIMS). Determined oxygen self-diffusion coefficients enable calculation of oxygen ion contribution to the total conductivity, which is shown to be small. Since very low contributions of the cations have to be expected, the total conductivity must be dominated by electron transport. Ion and electron conductivities are governed by different mechanisms with activation energies (1.9±0.1) eV and (1.2±0.07) eV, respectively. Further, the electromechanical losses are studied as a function of temperature by means of impedance spectroscopy on samples with electrodes and a contactless tone-burst excitation technique. At temperatures above 650 °C the conductivity-related losses are dominant. Finally, the operation of CTGS resonators is demonstrated at cryogenic temperatures and materials piezoelectric strain constants are determined from 4.2 K to room temperature.

Highlights

Piezoelectric components have broad potential for applications at extreme temperatures
Piezoelectric crystals of the langasite (LGS, La3Ga5SiO14) family are recognized as excellent candidates for low and high temperature applications as these crystals can be piezoelectrically excited from cryogenic temperatures to 1300 °C or more
The properties of CTGS have been investigated in a broad temperature range from cryogenic temperatures to about 1300 °C

Summary

Introduction

Piezoelectric components have broad potential for applications at extreme temperatures. The mass sensitivity of resonant sensors at high temperatures. Piezoelectric crystals of the langasite (LGS, La3Ga5SiO14) family are recognized as excellent candidates for low and high temperature applications as these crystals can be piezoelectrically excited from cryogenic temperatures to 1300 °C or more. They have been shown to have a high degree of thermal stability [2,3], which enables their application as gravimetric sensors [4,5,6]. CTGS (Ca3TaGa3Si2O14) is a relatively new compound of the langasite family, which has a fully ordered structure with lower conductivity and damping than LGS [7,8,9]

Methods

Results

Conclusion