About this Journal Submit a Manuscript Table of Contents
Journal of Materials
Volume 2013 (2013), Article ID 702946, 15 pages
http://dx.doi.org/10.1155/2013/702946
Research Article

Dielectric Properties of PbNb2O6 up to 700°C from Impedance Spectroscopy

1Physics Department, Egra SSB College, Egra, Purba Medinipur, West Bengal 721429, India
2Kendriya Vihar, C-4/60, V.I.P. Road, Kolkata 700052, India

Received 28 January 2013; Revised 28 March 2013; Accepted 29 March 2013

Academic Editor: Iwan Kityk

Copyright © 2013 Kriti Ranjan Sahu and Udayan De. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Piezoelectric materials have wide band gap and no inversion symmetry. Only the orthorhombic phase of lead metaniobate (PbNb2O6) can be ferroelectric and piezoelectric below Curie temperature, but not the rhombohedral phase. High temperature piezoelectric applications in current decades have revived international interest in orthorhombic PbNb2O6, synthesis of which in pure form is difficult and not well documented. Second problem is that its impedance spectroscopy (IS) data analysis is still incomplete. Present work attempts to fill up these two gaps. Presently found synthesis parameters yield purely orthorhombic PbNb2O6, as checked by X-ray Rietveld analysis and TEM. Present 20 Hz to 5.5 MHz IS from room temperature to 700°C shows its ferroelectric Curie temperature to be one of the highest reported, >574°C for 0.5 kHz and >580°C for 5.5 MHz. Dielectric characteristics and electrical properties (like capacitance, resistance and relaxation time of the equivalent CR circuit, AC and DC conductivities, and related activation energies), as derived here from a complete analysis of the IS data, are more extensive than what has yet been reported in the literature. All the properties show sharp changes across the Curie temperature. The temperature dependence of activation energies corresponding to AC and DC conductivities has been reexamined.