Microstructure And Dielectric Relaxation Of BT And ST Doped Ba(Fe0.5Nb0.5)O3 ceramics For Sensor Applications

¹University Department of Physics, V. K. S. University, Ara 802 301 Bihar, India

²Directorate of IE & IPR, DRDO, DRDO Bhawan, New Delhi 110011, India

Adv. Mater. Lett., 2012, Current Issue, 3 (3), pp 181-187

DOI: 10.5185/amlett.2012.3325

Publication Date (Web): Jun 10, 2012

Copyright © IAAM-VBRI Press

E-mail: singh_nk_phy27@yahoo.com

Abstract

Recently a new wave of interest has risen on complex perovskite structure due to their wide use in fabrication of multilayer ceramic capacitors, electrostrictive actuators, and electromechanical transducers. The polycrystalline ceramics of Ba(Fe_0.5Nb_0.5)O₃ (BFN) and its solid solutions 0.89Ba(Fe_0.5Nb_0.5)O₃-0.11BaTiO₃ (BFN-BT₁₁) and 0.89Ba(Fe0.5Nb0.5)O₃-0.11SrTiO₃ (BFN-ST11) were fabricated by a solid-state reaction Method. Processing parameters such as calcination temperature, sintering temperature and sintering durations were optimized to get best dielectric properties. It was found that the above ceramics sintered at 1250°C for 6 hours exhibited maximum density and uniform microstructure. X-ray diffraction studies of the compound showed the formation of single-phase monoclinic crystal structure at room temperature. Surface morphology of the compounds was studied by Scanning electron microscope (SEM). The effects of BaTiO₃ and SrTiO₃ substitution on the structure and on the electrical and ferroelectric properties of Ba(Fe_0.5Nb_0.5)O₃ samples have been studied by performing x-ray diffraction and dielectric measurements. The electrical properties of the samples were investigated in a frequency range of 100 Hz - 1 MHz and temperature range of 30-350 °C using complex impedance spectroscopic technique. The frequency-dependent electrical data are also analyzed in the framework of conductivity and impedance formalisms.

Keywords

Perovskite oxides, dielectric constant, electrical properties, scanning electron micrographs.