Structural and optical properties of silver-doped zirconia and mixed zirconia-silica matrices obtained by sol-gel processing

The annealing behavior of zirconia and mixed zirconia-silica matrices (With different ZrO2/SiO2 molar ratios) containing silver nanoclusters, synthesi zed by the sol-gel technique has been investigated. The film samples of the general formula (SiO2)(x)(ZrO2)((0.9-x))Ag-0.1 (x = 0, 0.225, 0.45, 0.675, and 0.9) were treated in different atmospheres (air, N-2, and 5%H-2-95%N-2 ) at temperatures ranging from 200 to 900 degrees C. The ZrO2 matrix underg oes a structural phase transition from amorphous to cubic-tetragonal polycr ystalline between 400 and 500 degrees C and on further raising the temperat ure near 600-700 degrees C the monoclinic phase also develops. On the contr ary, the ZrO2:SiO2 system remains amorphous up to similar to 700 degrees C. Ag nanoclusters are formed in all the systems. It has been observed that t he change in the ZrO2/SiO2 molar ratio is an effective way to control not o nly the overall refractive index of the matrix but also the Ag cluster size . The shifting of the surface plasma resonance position of Ag nanoclusters is observed as a function of the refractive indices of the matrix following the Mie theory. Samples where characterized by transmission electron micro scopy, Rutherford backscattering spectrometry, and optical spectrometry to correlate the cluster structure Lo their optical properties.