Structure and optical properties of PbTiO3-SiO2 nano-composites through sol-gel technique

Transparent glass with a composition of PbO-TiO₂-SiO ₂ have been prepared by hydrolysis and polycondensation of mixed metal alkoxides in solutions containing Pb(Ac)₂3H₂ O, Ti(OC₄H₉)₄, Si(OC₂H ₅)₄, C₄H₁₀O₂ and C₅H₈O₂. The crystallization behaviour in the gels were analyzed by differential thermal and thermogravimetric analyses (DTA-TG), X-ray diffraction (XRD) and infrared spectroscopy (IR) in detail, the linear refractive index was measured by ellipsometer, the refractive index at 632.8 nm was as high as 1.885, the optical energy band gap was estimated as 2.35 eV from the UV-optical absorption spectrum. The third-order nonlinear optical susceptibility (χ⁽³⁾) was determined by the degenerate four-wave mixing (DFWM) method, the χ⁽³⁾ value was as high as 6.63×10^-11 esu. It was shown that the materials exhibit large third-order susceptibility