PREPARATION AND PROPERTIES OF PT / SiO_2 FINE COMPOSITES
PT／SiO2精细复合材料的制备及其特性

T ultrafine Powders dispersed in SiO2 (PT / SiO2) were prepared by two step hydrolysis method. Si(OC2H5)4 was at first partically hydrolyzed by dropping it into a mixed solution of H2O, C2H5OH and HCl for first hydrolysis 1 hour. The resultant homogeneous solution was hydrolyzed with the second hydrolysis solution. In the second hydrolysis reaction, NH4OH was used as a catalyst instead of HCl, PT dispersed in solution such as H2O or C2H5OH was mixed.After stirring about three minutes, the solution was Poured into Polystyrene containers,covered and left for 2-3 days to form a stiff gel, followed by drying, and heated at lower temperture, PT / SiO2 fine composites were obtained. Structure changes of PT / SiO2 were analyzed by XRD, results indicated that grain size of PT particle in matrix was decreased with increased temperature. Dielectric properties and Raman spectra were analyzed. The third-order nonlinear optical susceptibility(X(3)) was determined by the degenerate four-wave mixing(DFWM) method, the X(3) value was as high as 10-11 esu. It was shown that the material exhibits large third order susceptibility.