2017 : The influence of local distortion on the electrical properties of the (1-x)(K0. 5Na0. 5) NbO3-x (Ba0. 8C0. 2) TiO3 system

Prof. Dr. Suasmoro


Abstract

In this work, the composition of (1-x)(K0.5Na0.5)NbO3-x(Ba0.8Ca0.2)TiO3 and the so-called (1-x)KNN-xBCT were successfully synthesised using a combination of solid-state reaction and co-precipitation oxalate methods. Phase identification and crystal structure determination were carried out by means of XRD pattern analysis. Local distortion due to the dopant was studied by XANES at the Nb L3-edge, XANES at the Ti K-edge, and EXAFS at the Ti K-edge. Electrical characterisation of dielectric properties and conductivity were investigated to elucidate the changes in local distortion. XRD analysis at room temperature concluded that while x=0 has an orthorhombic structure, x=0.1 and x=0.2 have as tetragonal structure. Furthermore, EXAFS analysis using Artemis revealed the oxygen octahedral distortion and distance of to its surroundings. Conductivity measurements at various temperatures showed that at …