Crystal Structure Analysis using Rietveld Refinement and Investigation of Electrical Properties of NaNbO3 Substituted CaTiO3 Ceramics.

Polycrystalline samples (1-x)CaTiO₃-xNaNbO₃ (x = 0, 0.10, 0.20, 0.30 and 0.40) were synthesized using solid state reaction method. Powder X-ray diffraction at room temperature showed that all of the samples' crystal structures were orthorhombic with Pbnm space group. Low Χ² values were obtained and there was good agreement between the computed and observed XRD patterns according to the Rietveld refinement. Impedance spectroscopy of the samples was investigated over a broad frequency and temperature range. Nyquist plots of the samples depicted a thermally activated non-Debye type relaxation mechanism. A decrease in dispersive nature of dielectric constant (ε') and tangent loss (tan δ) at low frequencies is noticed in the NaNbO₃ substituted samples rendering them a better stability. The samples became more resistive with NaNbO₃ substitution in CaTiO₃ lattice. Correlation between charge carriers and lattice has been established using modulus formalism. Imaginary impedance (Z'') and imaginary modulus (M'') have been employed to comprehend the conduction process in all the samples. [ABSTRACT FROM AUTHOR]