Impedance spectroscopy study of Na2Nb4O11 ceramic matrix by the addition of Bi2O3

The effects of different additions of Bi2O3 (0, 2, 5 and 10 wt.%) on Na2Nb4O11 ceramics have been studied by complex impedance spectroscopy analysis. The structural and dielectric properties of Na2Nb4O11-ceramics with Bi2O3 additions are also discussed as a possible material for microwave and radio frequency applications. Solid state reaction method was used for producing the target compound. The present work also reports on sample preparation, where polyvinyl alcohol was used as a binder to reduce the brittleness and the organic binder was burnt out during sintering process. X-ray diffraction at room temperature was used to identify phases formed as well as optimum calcinations conditions the production of Na2Nb4O11 powder. Analysis was carried out to identify the pure-phase specimen by Rietveld refinement method. Based on this method a structure with the lattice parameters (a = 10.840 angstrom, b = 6.162 angstrom and c = 12.745 angstrom; alpha = 90 degrees, beta = 106.4 degrees and gamma = 90 degrees) was found. The dielectric and electrical properties of Na2Nb4O11 for appropriate amounts of Bi2O3 additions has showed a considerable enhancement and overriding applications for microwave and radio frequency communications. The electrical behavior (complex impedance Z*, complex modulus M*) were studied over a frequency range (1 Hz to 1 MHz) and temperature (553-713 K). (C) 2013 Elsevier B. V. All rights reserved.