Abstract: 58SiO₂-(38-x) CaO-(x+4) P₂O₅ dried gels (x=0, 5, 10 and 15mol%) dried gel samples were synthesized at drying temperature 130°C by conventional sol-gel method. For synthesis used precursors are Tetraethyl ortho-silicate (TEOS), Tri ethyle phosphate (TEP), Calcium nitrate tetra hydrate for SiO₂, CaO and P₂O₅ compositions. Structural properties were studied for synthesized dried gels using X-Ray diffraction (XRD), Fourier Transform Infrared (FTIR), Raman spectroscopic analysis and Field Emission Scanning Electronic Microscopy (FESEM) with Energy dispersive X-ray diffraction (EDX) analysis. XRD pattern indicated that all dried gel samples have amorphous nature. FTIR spectroscopic analysis show that more P₂O₅ content leads to increasing degree of polymerization. Raman spectroscopic analysis indicates that increasing P₂O₅ content decreases the intensity of orthophosphate structures i.e., increasing P₂O₅ decreases orthophosphate structural units. Using FESEM average pore sizes of synthesized dried gels are calculated as 143.51, 149.54, 173.25, 182.81 micrometers for corresponding P₂O₅ mol% of 4, 9, 14 and 19 respectively. From all these observations increasing P₂O₅ decreases number of orthophosphate units and increases degree polymerization, it leads to increasing pore size on dried gel surface.

Keywords: Sol-gel; P₂O₅ composition; Calcium oxide; Pore size.