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Photoconductivity in sol-gel TiO2 thin films with and without ammonia treatment

Vomvas A., Pomoni K., Trapalis C., Todorova N.

Materials Science Poland

2007

Vol. 25, No. 3

809--816

Thin TiO2 sol-gel films, with and without ammonia treatment, were prepared using the dip-coating technique and then heat treated at 500 oC. The time dependences of the photoconductivity at various light intensities were studied in vacuum and in air at 27 oC. The transient photoconductivity is very sensitive to the environment and dramatically higher than the dark one for samples both in vacuum and in air. The results are discussed in terms of the competition of the photogeneration, recombination, thermal release, and the influence of NH3 treatment.

Oxynitride glasses prepared by densification of nitrided silica aerogels.

Szaniawska K., Murawski L., Pastuszak R., Walewski M.

Optica Applicata

2000

Vol. 30, nr 4

529-536

Silica aerogels were nitrided by ammonia treatment at temperatures ranging from 700 degrees C to 1300 degrees C. It was found that the amount of nitrogen incorporated in silica aerogel depends on the final temperature of ammonolysis and on the time of heat treatment. The specific surface area of nitrided aerogels remains large and decreases with the temperature of ammonolysis and with nitrogen content. Nitrided aerogels can be converted into dense homogeneous oxynitride glasses containing 8.4-13.0 wt% of nitrogen by heat treatment at 1600 degrees C in vacuum or in nitrogen atmosphere. The spectra of the Fourier transform infrared spectroscopy (FTIR) reveal that Si-N bonds exist in nitrided aerogels as well as in oxynitride glasses.