Investigation of Ba and Ti sites occupation effects on structural, optical and dielectric properties of sol gel processed Y-doped BaTiO3 ceramics

Abstract

Incorporation of chemical elements into the A and/or B sites of the ABO3 perovskite structure generates disorder (topological disorder, oxygen vacancies, …) in this structure which gives rise to effects more or less important on its chemical and physical properties. In particular, the structure, microstructure and the dielectric properties are affected under the effect of doping. In this regard, we investigate the above mentioned effects on BaTiO3 (BT) compounds doped with different percentages of Y. Indeed, X-Ray Diffraction (XRD) and Raman analyses show that Yttrium (Y) may replace both Ba and Ti atoms, and noticeably reduces the grain size of the sintered samples in conformity with Scanning Electron Microscopy (SEM) images. We show that the generated disorder consecutive to incorporation of Yttrium is also evidenced by the values of Urbach energy. We obtain relatively high values of the permittivity under doping without relaxation effect of this parameter but with the presence of a weak diffuse character of the ferro-to-paraelectric transition. Moreover, we show that resonances may be induced in BT under doping with Yttrium, and that the Positive Temperature Coefficient of Resistivity (PTCR) is present in the undoped (BT) and Y-doped BT samples.