Synthesis, crystal structure, dielectric and optical properties of a new rare earth double perovskite: Ca2CeNbO6

In order to develope and understand the phenomena involved in producing advanced materials, a rare earth double perovskite oxide calcium cerium niobate, Ca2CeNbO6 (CCN) is synthesized for the first time. The x-ray diffraction pattern of CCN at room temperature (300 K) shows orthorhombic perovskite structure, with the lattice parameters, a = 9.36 angstrom, b = 6.61 angstrom and c = 5.88 angstrom and alpha = beta = gamma = 90 degrees. A scanning electron micrograph shows the formation of grains with average size similar to 2 mu m. Impedance spectroscopy and Fourier transform infrared spectroscopy are applied to investigate the dielectric and optical properties of CCN. The frequency-dependent electrical data are analyzed in the framework of the conductivity and modulus formalisms. The experimental data of real part of dielectric permittivity (epsilon' and imaginary part of electric modulus (M '') are fitted with Davidson-Cole equation to explore the idea of dielectric relaxation (conduction) mechanism in CCN. The frequency-dependent conductivity spectra follow a power law. The scaling behaviour of imaginary electric modulus (M '') suggests that the relaxation describes the same mechanism at various temperatures. (C) 2011 Elsevier B.V. All rights reserved.