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Proceedings Paper

Transient stress evolution and crystallization in laser-irradiated amorphous titania sol-gel films
Author(s): Gregory J. Exarhos; Nancy J. Hess; Susanne Wood
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Paper Abstract

Amorphous Ti02 sol-gel films are irreversibly transformed to a crystalline anatase phase when heated to temperatures in excess of 575 K or subjected to intense pulsed or CW laser irradiation. The laser-induced transformation is initiated as a result of impurity absorption and subsequent heating, and results in densification and relative changes in compressive stress of the film. Isothermally annealed films exhibit a decrease in compressive stress as crystallization proceeds while an increase in compressive stress followed by a decrease in stress is observed when crystallization is laser-induced. Raman spectroscopy has been used to characterize the crystallization ingrowth kinetics and is used in this work as a real time probe of both film temperature and localized stress which can be evaluated from shifts in lattice phonon frequencies measured in real time during laser irradiation. The laser not only induces the phase transformation but excites inelastic Raman scattering from which film stress and temperature can be estimated. A second approach for the determination of these parameters requires incorporation of a thin ruby film between the titania and silica substrate. Here, the wavelength shift of the laser-induced ruby fluorescence can be used to quantify interfacial stress; the fluorescence lifetime measurements are used to determine temperature. The advantages and limitations of these techniques for evaluating transient stress and temperature evolution in thin titania films subjected to CW laser irradiation will be discussed.

Paper Details

Date Published: 29 July 1992
PDF: 12 pages
Proc. SPIE 1624, Laser-Induced Damage in Optical Materials: 1991, (29 July 1992); doi: 10.1117/12.60094
Show Author Affiliations
Gregory J. Exarhos, Battelle Pacific Northwest Lab. (United States)
Nancy J. Hess, Battelle Pacific Northwest Lab. (United States)
Susanne Wood, Washington State Univ. (United States)


Published in SPIE Proceedings Vol. 1624:
Laser-Induced Damage in Optical Materials: 1991
Harold E. Bennett; Lloyd L. Chase; Arthur H. Guenther; Brian Emerson Newnam; M. J. Soileau, Editor(s)

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