Structural and electrical characterization of cadmium phosphate glasses doped with different concentration of sodium chloride

Abstract

Abstract
The electrical characteristics of cadmium phosphate glasses doped with varying concentrations of sodium chloride[Cd3(PO4)2]1-x[NaCl]x, where x = 0%, 2%, 4%, and 6%, were investigated with respect to both dopant levels and temperature. Electrical impedance spectroscopy was employed, and impedance measurements were taken across the frequency spectrum from 102 Hz to 106 Hz using a Solartron 1260 Impedance/Gain-phase Analyzer. The samples were characterized by scanning electron microscopy–energy dispersive X-ray spectroscopy, X-Ray diffraction analysis and
Fourier Transform Infrared Spectroscopy. The findings revealed a decrease in bulk resistance with increasing temperature and dopant concentration, indicating a rise in DC-conductivity and suggesting a semiconducting behavior in the material. Moreover, the activation energy values were noted to decrease as dopant concentration increased. Conversely, the relaxation peak diminished and shifted towards higher frequencies with escalating dopant concentration and temperature, suggesting that at elevated temperatures, defects and vacancies play a more significant role in the relaxation behavior of the material. Analysis of the AC-conductivity variation with frequency delineated two distinct regions: a low-frequency region where AC-conductivity increased with frequency, indicative of a "pumping force" effect aiding charge carrier movement through various conduction states, and a high-frequency region or frequency-independent zone signifying a transition towards a more ohmic behavior in the material. The study highlighted a decrease in both the dielectric constant and dielectric loss with rising temperature and frequency across all dopant concentrations. This decrease was attributed to the enhanced movement of particles and atoms within the material at higher temperatures, resulting in reduced internal charge relaxation and electrode polarization, as well as increased scattering that impedes the effect of the electric field. Furthermore, the Reaction Coefficient "s" was found to be less than one, suggesting that the conduction mechanism can be elucidated in terms of the Correlated Barrier Hopping (CBH) model.