Synthesis, characterization and ionic conductivity of Ca8−xSrxBi2(PO4)6O2 for x = {3, 4, 5}

Solid solutions in the Ca8−xSrxBi2(PO4)6O2 system were synthesized using the solid-state reaction method. The structures were refined by Fullproof program which is based on Rietveld method formalism. The Sr2+ ions were noted to occupy two sites (4f) and (6h), with a strong preference for (6h) sites. The heavy atoms Bi3+ preferentially occupied the (6h) site. The charge distributions (CD) (through CHARDI-it method) were used to validate the structures. The frequencies observed in the Raman and infrared spectra were explained and discussed and comparisons with Fluoroapatites and other oxyapatites. The electrical properties of the samples were also studied by the complex impedance method between 600 and 725 °C. The results revealed that electrical conductivity increased with increasing strontium content.