Microwave and optical properties of monoclinic Bi₂Zn_2/3Nb_4/3O₇ thin films

¹ Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro 3810-195, Portugal
² Center of Material Science, University of Allahabad, Allahabad 221 006, India
³ School of Physics, University of Hyderabad, Hyderabad 500 046, India

^a sudhi_skp@yahoo.co.in

Received: 25 November 2010
Revised: 7 June 2011
Accepted: 21 November 2011
Published online: 23 April 2012

Abstract

Bismuth zinc niobate (Bi₂Zn_2/3Nb_4/3O₇) thin films were deposited by PLD on fused silica substrates at different oxygen pressures. The structural, microwave dielectric, optical and Raman characteristics of these thin films were systematically studied for both the as-deposited films and films annealed at 600 °C. The microwave dielectric constant at a frequency of 10 GHz of the annealed m-BZN films varied from 56 to 71, whereas the dielectric loss tangent varied from 1.8 × 10⁻⁴ to 3.5 × 10⁻⁴ as a function of deposition pressure. The as-deposited films exhibit refractive index in the range of 2.06–2.15 with an optical absorption edge value between 3.59 and 3.67 eV. The observed Raman scattering in m-BZN thin films was slightly shifted toward the higher frequency which reveals that the local lattice disorder changes whereas the structure remains the same monoclinic in thin film as well as in bulk.