Structural and ac conductivity studies of sodium tetralead triphosphate compound

Sodium tetralead triphosphate NaPb4(PO4)3 compound was synthesized by the solid-state reaction method, characterized through X-ray powder diffraction, Raman and electrical impedance spectroscopy. A Rietveld analysis of powder X-ray diffraction has shown that the title compound crystallizes in the hexagonal system at room temperature, space group P63/m. A pellet of 92% density was used for the electrical measurements. All electrical measurements of real and imaginary components of the impedance parameters were made over a wide range of temperature (598-720) K and frequency (209 Hz-1 MHz) using a Tegam 3550 impedance analyzer interfaced to a compatible computer. Ac conductivity data affirm that for high frequencies σac is proportional to ωs. The frequency exponent values increase with increasing temperature revealing that the non-overlapping small polaron tunneling is the appropriate conduction mechanism.