Spectroscopic studies and Rietveld refinement of strontium-britholites

Abstract Strontium-britholites whose chemical formula was Sr 10− x La x (PO 4 ) 6− x (SiO 4 ) x F 2, where x =0, 1, 2, and 4 were prepared by solid state reaction. The structural refinement carried out using the Rietveld method indicated that La 3+ ions were located into the two sites with a strong preference for metal (2) sites especially for low contents. A progressive shift of the F − position along the c -axis outside the centre of the triangle formed by metal (2)-atoms was observed with the increase of x . The infrared and Raman spectra exhibited the characteristic vibration modes of PO 4 and SiO 4 groups confirming the incorporation of this last group into the apatite structure. The 29 Si MAS-NMR spectra exhibited one resonance peak confirming the data obtained by X-ray diffraction, indicating that P and Si were located in the same crystallographic site.