Crystal structure characterization and AC electrical conduction behavior of sodium cadmium orthophosphate

Sodium cadmium orthophosphate NaCdPO4 was prepared by solid-state reaction method at high temperature under air atmosphere. Structural, morphology and electrical properties have been investigated. X-ray powder diffraction analysis indicated that the sample is well crystallized in the orthorhombic maricite structure with Pmnb space group. The composition and morphology of the compound were performed by energy dispersive spectroscopy coupled with scanning electron microscope. Electrical properties were carried out in the frequency range 209 Hz-1 MHz at various temperatures 595-700 K using impedance spectroscopy technique. Nyquist plots analysis revealed the presence of two contributions at different temperatures associated with grain and grain boundary. In order to explain the impedance results an equivalent circuit has been proposed. The AC conductivity was analyzed by Jonscher's power law of frequency (sigma (ac) (omega) a A omega (s) ). At high frequency, the conduction mechanism was well interpreted in term overlapping large polaron tunneling.