Role of zirconium on the structural film evolution and on the optical properties of sol-gel hybrid organic/inorganic glass films

The growing and curing dependence of structural and optical properties of sol-gel Si- and Zr-based films was studied by using the fast Fourier Transform IR (FTIR) spectroscopy in the 500-5000 cm(-1) range. Samples are prepared by means of a spin-coating technique with different ratios between the precursor fraction. The introduction of Zirconium in the starting solution confers both rigidity and high refractive index to the films. The IR spectra are characterized by three main absorption regions: from 700 to 1250 cm(-1) the ZrO and Si-O-Si stretching modes are dominant, from 1250 to 1800 cm(1)(-) the absorption is strongly dependent on the Zr content and the region from 2750 to 3500 cm(-1) is characterized by the CH2 and CH3 vibrational peaks and by the OH broad band. The curing process is monitored after isochronal thermal treatments in the range 50-500degreesC.