Optical and Nonlinear Optical Properties of Nanostructured Aluminum Oxyhydroxide: The Effect of Thermal Treatmentстатья
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Дата последнего поиска статьи во внешних источниках: 19 декабря 2017 г.
Аннотация:We studied effect of thermal annealing at temperatures from 100 to 900 °C on the light scattering, photoluminescence and nonlinear optical properties of nanoporous aluminum oxyhydroxide, prepared by selective oxidation of the surface of liquid-metal fusion at room temperatures. A significant increase of the photoluminescence intensity accompanied by the spectrum expansion to longer wavelength was found in all annealed samples. The blue-shift behavior for the photoluminescence peaks and an appearance of new low-energy peak at 2.28 eV have been observed after annealing of the native material at 100 °C. This fact is explained by annealing-induced structural transformations of the material, which lead to redistribution of the luminescent oxygen-related centers. We consider that the annealing results in the formation of oxygen vacancies and divacancies, which gives the enhanced photoluminescence in the wide energy range. An impact of the annealing on photoinduced absorption variation under self-action of picosecond range laser pulses was observed. The water desorption and phase transformations after annealing at different temperatures result in modifications of the nonlinear optical response, which can be used for the optical diagnostics of structural reorganization of ultraporous media under thermal treatment. The study of both the liner optical and nonlinear optical properties reveals the morphological structure transformations in the investigated transition aluminas.