Papers by Keyword: Photochromic Effect

Abstract: Photochromic materials are sensitive to light when such a material exposed to the sunlight or UV irradiation, it can change color very quickly and turn back to its original uncolored form by removing light resource. Photochromic powder at different ratios in polymeric gel were prepared and coated on ceramic surfaces by using spray technique. This coating technique provided to form homogeneous layer structure on surface. By using polymeric gel, photochromic coatings were occurred at low temperatures with good adhesion. After heat treatment fast response photochromic coatings were achieved. Surface morphology of coatings on ceramic surfaces were investigated by scanning electron microscopy (SEM), the photochromic effect and optical characterization of coatings were analyzed by using Minolta 3600-d spectrophotometer.

Abstract: EPR and optical absorption measurements have been performed on nearly stoichiometric lithium niobate single crystals with iron in traces and in 0.1% molar nominal amount. Thermal treatments in reducing atmosphere allowed to obtain samples with different Fe2+/Fe3+ ratios. The Fe2+/Fe3+ dynamic has been observed by irradiating the samples with UV and visible light in the temperature range 4-300 K: the photochromic effect resulted to be more evident in the strongly reduced crystals. A simple model to explain the photochromic behavior in nearly stoichiometric LiNbO3:Fe is proposed.