P.Sarah
Vardhaman College of Engineering, India
Title: Influence of rare earths on the electromechanical coupling factor and operating temperature of strontium bismuth titanate
Biography
Biography: P.Sarah
Abstract
Piezoelectric ceramics are widely studied for numerous electronic functional device applications, e.g. in microprocessors resonators, mobile communications filters, inject printers’ actuators and for detecting shock sensors and hard disc drives, etc. The piezoelectrics used for these applications are commonly Lead based materials because of their good piezoelectric behavior. These Lead based piezoelectrics have two major deficits viz. low operating temperatures and toxicity. Keeping these factors in view, the present study attempts to find alternate environment friendly piezoelectrics with good piezoelectric properties and enhanced operating temperatures. Strontium Bismuth Titanate is a suitable alternate piezoelectric.
Strontium Bismuth Titanate SrBi4Ti4O15 (SBT), a member of the Bismuth Layered Structured Ferroelectric (BLSF), is gaining attention because of its Curie temperature and its ability to be tailored for required applications with suitable composition modifications. The higher Curie temperature (535oC) makes it useful for applications at higher temperature. The electromechanical coupling factor of SBT is around 0.40 while that of PZT is of the order of 0.70. The present study analyses the influence of rare earth substitution and the preparation method on the electromechanical coupling factor and Curie temperature of lead free piezoceramics.
This paper evaluates the impact of Rare Earth (RE) substitution on SrBi4Ti4O15 (SBT), (RE: Zirconium (Zr), Samarium (Sm), Neodymium (Nd), Holmium (Ho), Praseodymium (Pr), Dysprosium (Dy)) and also the impact of processing method on Curie temperature and kp (electromechanical coupling factor) of SBT. The temperature at which phase transition from ferroelectric to paraelectric phase occurs is called the Curie temperature (Tc). In this study, the dielectric constant of La-substituted (SBT), Sm- substituted (SBT), Nd- substituted (SBT) has proved to decrease and the TC increased for all the RE substituted SrBi4Ti4O15 except for that with Zr.
An increase in the Tc is observed due to the rare-earth ions substitution and the piezoelectric behavior is enhanced with the increase in rare-earth ions content making these materials useful for piezoelectric applications at temperatures greater than 550oC.