Structure and Polar Properties of SrTiO3-xNa0.5Bi0.5TiO3 Ferroelectric System

Abstract

Ferroelectric materials exhibit interesting dielectric and piezoelectric properties. While for over six decades, lead-zirconate titanate (PZT) has been the most sought after piezoelectric material for actuator, transducer, and sensing applications, the toxicity associated with Pb has spurred research in lead-free alternatives in the last two decades. Na0.5Bi0.5TiO3 (NBT) and its solid solutions with other perovskite materials have attracted a great deal of interest. Majority of the studies thus far have focussed on the solid solution of NBT with BaTiO3 (BT) and Ka0.5Bi0.5TiO3 (KBT) as these systems exhibit morphotropic phase boundary similar to that of PZT. In this thesis, the focus is on the solid solution of NBT with SrTiO3 (ST). Unlike BT and KBT, ST is a quantum paraelectric. A comprehensive investigation of this system was carried out using a variety of experimental techniques like X-ray diffraction, Neutron diffraction, Electron diffraction, Raman spectroscopy, Eu+3 photoluminescence, etc. Together with physical properties measurements like dielectric, ferroelectric and electrostrain, we revealed several interesting phenomenon not known before.