Synthesis And Characterization Of Two New Antimony Phosphates Co0,5alsb(PO4)3 And Mg0,5fesb(PO4)3
H. Sinouh, A. EL Bouari, S. Benmokhtar, L. Bih, A. Faik
Abstract
Two new antimony phosphates Co0,5AlSb(PO4)3 and Mg0,5FeSb(PO4)3 were synthesized for the first time by the solid-state reaction method. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Co0,5AlSb(PO4)3 crystallizes in the space group R-3c (N°167) (ah = 8.23±0.01Ǻ, ch = 21.94±0.02Ǻ). Mg0,5FeSb(PO4)3 crystallizes in the monoclinic space group P21/n (N°14) (am =11.54 Ǻ, bm = 8.83± 0.02 Ǻ, cm = 8.39± 0.01 Ǻ, β = 96.67°± 0.09). Raman and infrared spectra were recorded and assignments of the stretching and bending vibrations of the PO43- tetrahedra were made. The number of the peaks observed is in good agreement with that predicted by the factor group analysis of the R-3c et P21/n space group respectively. Vibrational spectral studies of two antimony phosphates were collected in-situ at room-pressure and at elevated temperatures, up to 430 oC. At elevated temperatures in air, Mg0,5FeSb(PO4)3 seems to be stable, but
Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC).
Co0,5AlSb(PO4)3 show a transition at 380°C and decomposes at 930°C. This result has been confirmed by differential scanning calorimetric study (DSC).