Multi color density photochromism in reduced tridymite BaMgSiO4 by wavelength of irradiation light

We have investigated the multi color density photochromism in reduced tridymite BaMgSiO4 (BMS-H) semiconductors, which can utilize green light, blue light, sunlight and ultraviolet light. It is found that BMS-H is one of visible light photochromic material with high response. BMS-H changes color from white to pink by sunlight irradiation or 405 nm light. The colored BMS-H is irradiated with 532 nm light, and the sample is substantially bleached. Furthermore, the colored BMS-H changes bright pink by 365 nm light irradiation. The pink color density of BMS-H strongly depends on the wavelength of irradiation lights. After heat treatment of 250 degrees C for three minute in air, the sample is substantially bleached, and the bleached sample regains its color on light irradiation. BMS-H shows high reversibility in the coloring-bleaching processes. The pink color of BMS-H irradiated 365 nm light could be observed by visual confirmation after 22 days. The photogenerated colored state is comparatively stable in air at room temperature. (C)2011 The Ceramic Society of Japan. All rights reserved.