Effect of X-ray irradiation on solarization and crystallization of photosensitive glasses containing Ce, Sb, Sn and Ag M.H. Imanieh a , B. Eftekhari Yekta a, * , V. Marghussian a , A. Aghaei b a Ceramic Division, Department of Materials, Iran University of Science and Technology, Tehran, Iran b Ceramic Division, Material and Energy Research Center, Tehran, Iran article info Article history: Received 21 August 2007 Received in revised form 5 March 2008 Available online 27 May 2008 Keywords: Glass-ceramics Optical spectroscopy abstract The effect of X-ray irradiation on the solarization and crystallization of a lithium silicate glass was inves- tigated in this research. The results showed that the X-ray power has a significant effect on the amount of solarization, and the crystallization temperature of the glass. Applying an X-ray power of 2400 W on glass containing the photosensitive elements of Ce, Sb, Sn and Ag led to reduction of the DTA crystallization peak temperature from 704 to 590 °C. UV spectroscopy showed that solarization of irradiated glasses containing Ce, Sb and Sn ions was responsible for formation of Ag clusters and reduction of crystallization temperature of glasses. Microstructural analysis also showed that the solarized glasses had a finer micro- structure relative to that of the non-irradiated one. These differences attributed to changes in crystalliza- tion mechanism observed in the non-irradiated glass. Ó 2008 Elsevier B.V. All rights reserved. 1. Introduction Photosensitive glasses are sensitive to electromagnetic radia- tion; therefore, exposing them to an electromagnetic radiation leads to ejection of photoelectrons and oxidation of Ce 3+ to Ce 4+ (Eqs. (1) and (2)) and Sn 2+ to Sn 4+ (Eq. (3)), reduction of Ag + ions to its atoms (Eq. (4)) and subsequently formation of Ag clusters in the heat-treated glasses (Eq. (5)) [1–3], 2Ce 4þ + Sb 3þ $ 2Ce 3þ + Sb 5þ , ð1Þ Ce 3þ + hm ! Ce 4þ + e, ð2Þ Sn 2þ + hm ! Sn 4þ + 2e, ð3Þ Ag þ +e ! Ag, ð4Þ xAg  ! heat-treatment Ag x ; ð5Þ where x is the number of silver atoms aggregated into clusters. Radiation produces some direct and indirect measurable changes in the glasses. In some cases, the effect is readily observa- ble immediately upon irradiation. In other cases, thermal treat- ment is required to bring about the observed changes. On the whole, the result of the mentioned reactions will be atomic silvers and/or silver clusters which act as nucleant for precipitation of lithium-meta-silicate during post heat-treatment of irradiated glass [1–4]. Similar to other glass-ceramic systems, the more nucleation sites leads to more reduction of crystallization temper- ature and finer crystalline size. Therefore, to attain the above-men- tioned condition, various energetic radiation such as UV [2,3,5], laser beam [6,7], x [8], c [4] and proton [9,10] radiations have been used for different photosensitive glasses until now. As indicated in the above-mentioned equations, the mechanism of silver cluster- ing is well known; however, it seems that the role of irradiation beam on the extension of solarization, crystallization temperature and the microstructure for various glasses needs to be studied more. In this work, the effect of X-ray irradiation on solarization of photosensitive lithium silicate based glasses containing cerium, antimony, tin and silver elements were studied. In this way, eval- uation of the DTA crystallization peak temperature of glasses, their optical absorbance, and microstructures of heat-treated glasses be- fore and after X-ray irradiation, were considered. 2. Experimental Glasses were prepared by melting reagent grade chemi- cals(extra pure) in alumina crucibles at 1450 °C in an electric kiln for 1 h. Exception was silica, which was prepared through acid washing of an commercially grade silica powder. The purity of re- sulted silica powder was more than 99.8 wt%. Our major experiments were performed on two different glass compositions; their main chemical composition was the same, but they differ in their photosensitive elements. The base glass named G B contained 75.00 wt% SiO 2 , 5.00 wt% Al 2 O 3 , 12.00 wt% Li 2 O, 0022-3093/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2008.04.007 * Corresponding author. Tel.: +98 9121593292; fax: +98 2177240480. E-mail address: beftekhari@iust.ac.ir (B. Eftekhari Yekta). Journal of Non-Crystalline Solids 354 (2008) 3752–3755 Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/locate/jnoncrysol