Synthesis and Characterization of Homovalent and Heterovalent Substituted Strontium Bismuth Titanate Ceramic

Abstract

Bismuth layer structure ferroelectrics also known as Aurivillius family of oxides are currently attracting significant attention due to their interesting fundamental physics as well as the potential applications. Strontium Bismuth Titanate (SrBi4Ti4O15 (SBT)) is a well-known member of the bismuth oxide layer structure ferroelectric material and has the potential for applications such as non volatile ferroelectric random access memory, high temperature piezoelectric sensors acting as force, noise, and vibration sensors operated at operating temperatures. However the physical properties and the phase transition of this material vary as a function of intensive parameters (i.e., temperature, frequency, pressure, electric field). In the present dissertation we have prepared SBT at various calcinations and sintering temperatures to optimize the synthesis condition. Again to improve the electrical behaviour, A-site and B-site homo-valent/hetero-valent element has been substituted in SrBi4Ti4O15 ceramic and their detail structural and electrical properties are studied. In his regard Sr1-xBaxBi4Ti4O15, SrBi4-xLaxTi4O15, Sr1-xGd2x/3Bi4Ti4O15, SrBi4Ti4-xZrxO15, SrBi4-(2x/3)Ti4-xWxO15 ceramics has been prepared by optimized synthesis condition. The structural, micro structural and electrical properties of the modified system were carried and analysed in detail. The homo(iso)-valent substitution in the A-site decreases the transition temperature where as the hetero(alio)-valent substitution increases the transition temperature. The homo-valent modification in the B-site slightly increases the transition temperature but the hetero-valent modification decreases the transition temperature. The ferroelectric and piezoelectric properties are carried out at room temperature. Both the hetero and homo-valent substitution enhances the ferroelectric and piezoelectric behaviour. The conduction behaviour of the all the compositions are studied with respect to impedance study at various temperatures and frequencies. The activation energy was calculated for conduction mechanism and correlated with the oxygen vacancies. It can be observed that substitution in SBT ceramic enhances the dielectric, ferroelectric and piezoelectric behaviour, so that the materials can be used as high temperature piezoelectric and memory application.