Dielectric constant and electrical study of solid-state electrolyte lithium phosphate glasses

A detailed analysis of dielectric response and electrical properties of lithium phosphate glasses (LiPO3) as a function of temperature from 20 °C (room temperature) to 170 °C and frequency from 4 Hz to 4 MHz was done using impedance spectroscopy technique. X-ray diffraction (XRD) and differential scanning calorimetry were used to study the structure phase and thermal analysis of the material under investigation, respectively. XRD pattern confirms the amorphous nature of the material. The total conductivity shows two distinct regions, dc conductivity and ac conductivity (σtot(ω) = σdc + A ωr). The ac conductivity’s exponent factor r was found invariant at low-temperature zone and temperature dependent at high-temperature zone. The frequency exponent factor values and its temperature dependence suggested that the jump relaxation model is the best model that can describe the conduction mechanism. Various parameters such as bulk conductivity, dc conductivity, dielectric relaxation time, transition time and the associated activation energies were calculated and discussed. The activation energy of bulk conductivity, dc conductivity and the dielectric relaxation was found to have similar value (0.29 eV). Thermodynamic parameters, such as free energy of activation (ΔF), enthalpy of activation (ΔH) and entropy of activation (ΔS), have been calculated and discussed as well.