Electric properties of Holmium substituted SrBi4Ti4O15ceramic for High Temperature Piezoelectric Applications

Abstract

Piezoelectric ceramics have been widely used for several applications, such as those in filters for mobile communications; resonators for microprocessors, actuators for inject printers and sensors for detecting shock and hard disc drives (HDDs). Recently the family Aurivillius Bismuth Layer-Structure Ferroelectrics (BLSFs) has received attention for their use in the nonvolatile Ferroelectric Random Access Memory (FeRAM). In addition BLSFs have their application in electronic functional devices such as resonators and high temperature sensors etc. In the case of resonator applications, piezoelectric elements are used as inductors. Furthermore BLSFs generally have higher Curie temperature than PZT based materials. Therefore BLSFs are an attractive alternative to PZT based materials for high temperature piezoelectric sensor applications. The Electric properties of the SrBi4Ti4O15 (SBT) compound, which is a member of the family of Aurivillius Bismuth Layer-Structure Ferroelectrics, are studied using a rare earth, Holmium dopant. SrBi4-xHoxTi4O15 (x=0.00, 0.02, 0.04 and 0.06) (SHBT-x) sample is prepared by solid state sintering method. The crystal structure of SBT remains orthorhombic even after Ho substitution. The microstructure and grain size of the samples were studied using Scanning Electron Microscopy (SEM). Studies of dielectric constant and dielectric loss with temperature at different frequencies have been carried out. Introduction of Holmium increased the Curie temperature of SBT thus making this ceramic suitable for sensor applications at higher temperatures. The electromechanical coupling factor also is studied.