A STUDY OF FREE-VOLUME HOLE DISTRIBUTIONS IN XTIO(2)CENTER-DOT(1-X)SIO2 BY POSITRON-ANNIHILATION SPECTROSCOPY

Positron annihilation spectroscopy has been used to obtain information about the small-pore structure of the system xTiO(2) .(1 - x)SiO2 (x = 10, 30 mol%). The pore radius probability distribution functions hav e been obtained from the ortho-positronium lifetime probability distri bution functions, determined from lifetime spectra using the CONTIN (P ALS-2) program. The linearity of the variation of S versus W has been used to check the similarity of (or difference between) the defect str uctures of the samples prepared under different experimental condition s.