Rietveld refinement, electronic structure and ionic conductivity of Sr4La6(SiO4)6F2 and Sr4La6(SiO4)6O ceramics

Abstract In this paper, we report the effect of the tunnel anions on the ionic conductivity of Strontium-Lanthanum silicate apatites. The Sr 4 La 6 (SiO 4 ) 6 F 2 and Sr 4 La 6 (SiO 4 ) 6 O ceramics were prepared by the solid state reaction method. X-ray diffraction, NMR spectroscopy and Raman measurements were performed to investigate the crystal structure and vibrational active modes. Moreover, the electronic structures of the crystals were evaluated by the first-principles quantum mechanical calculation based on the density functional theory. Finally, the ionic conductivity was studied according to the complex impedance method.