Study on photochromism in SrTiO3:Fe ceramic powder

The photochromic effect in Fe-doped SrTiO3 ceramic powder was investigated. The photochromic process for the powder is reversible. Its colour changes very quickly, approximately in 1 s, when exposed to < 485 nm light. The induced coloured state can be completely bleached at room temperature in several days, and the bleaching time shortens with increasing temperature. The coloured state can also be completely bleached with 535-800 nm light; the optical bleaching time is several minutes. The photochromic properties of the powder were studied using an optical technique. It was found that three optical absorption bands peaking at 425 nm, 490 nm and 590 nm appeared in the dopant-induced photochromic spectrum when exposed to UV-vis-NIR light, and two optical absorption bands peaking at 430 nm and 580 nm appeared in the dopant-induced photochromic spectrum when exposed to > 485 nm light. A detailed discussion about the colouring and bleaching processes was provided on the basis of the experimental data and the literature. In addition, the colour characteristics of the powder were also described before and after UV irradiation. (C) 1997 Elsevier Science Limited.