Conductivity and Complex Electrical Formalism of the Iron-Doped PbLaTiO 3 Ferroelectric Relaxor

Abstract

Polycrystalline perovskite nanomaterials (Pb 0.88 La 0.12 ) ( Fe x Ti 1 - x ) 0.97 O 3 were prepared by sol-gel reaction method. The crystal structure examined by X-ray powder diffraction indicates that the material was single phase with pseudocubic structure. EDX and SEM studies were carried out in order to evaluate the quality and purity of the compounds. The crystal symmetry, space group, and unit cell dimensions were determined from Cell-Ref software, whereas crystallite size was estimated from Scherrer’s formula. A correlation between grain size and diffuse character for the samples has been observed. Dielectric studies exhibit a diffuse phase transition characterized by a strong temperature and frequency dispersion of the permittivity and a relaxor behaviour. We have observed that dielectric constant decreases and ac conductivity increases with the frequency. The dielectric relaxation has been modeled using the Curie-Weiss and modified Curie-Weiss laws. The calculated activation energy E a for x = 1 % and 3% was between 0.91–2.1 eV and 0.425–1.08 eV, respectively. The relaxation times were estimated from the Arrhenius law.