Thermal and Electrical Characterization of (1-x)Na2O-xAl2O3-P2O5 System Glasses

Phosphate glass with different Al2O3 and Na2CO3 content [80NaH2PO4-(20-x) Na2CO3-xAl2O3 with a step of 0 to 4] were prepared through melt quenching technique furnace at 900°C. In order to determine the structure and microstructure modification of the samples after heat treatment the IR and Raman spectroscopy were performed. The X-ray diffraction (XRD) result indicated the amorphous nature of the as prepared glass. The result obtained by differential scanning calorimetry (DSC) revealed a good thermal stability in the temperature range of 25 to 400°C. The impedance Nyquist diagrams were investigated and modeled by resistors and constant phase elements (CPE) equivalent circuits. These measurements showed a non-Debye type dielectric relaxation. Both the AC and DC conductivity, dielectric constant, and loss factors were determined. Thermal activation energies were also calculated. A change in the electrical conductivity and activation energy with changes in the chemical composition were observed. Also, a transition in the conduction mechanism from ionic to mixed ionic polaronic was noted. In the same line, electrical modulus and dielectric loss parameters are also deduced. Their frequency and temperature dependency exhibited relaxation behavior. Likewise, activation energies value obtained from the analysis of M’’ and those obtained from the conductivity were in close agreement, indicating the optimal character of the preparation conditions.