Phototropic Glasses Activated by TlCl |
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Authors: | SUMIO SAKKA J D MACKENZIE |
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Affiliation: | Department of Industrial Chemistry, Mie University, Tsu, Mie-Ken, Japan;Materials Department, University of California, Los Angeles, California 90024 |
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Abstract: | Phototropic glasses in which TlCl crystallites play an active role were developed. When glasses containing Tl and Cl were reheated at 420° to 480°C for 3 to 20 h, phototropic glasses were obtained which were transparent, translucent, or opaque, depending on the temperature and time of heat treatment. X-ray powder diffraction patterns of these glasses indicated the presence of TlCl crystallites. The optical absorption in the visible region which developed in the glass after uv exposure was similar to that developed in TlCl crystals prepared by melting TlCl powder. These facts suggest that the phototropy is caused by TlCl crystallites precipitated in the glass by heat treatment. Optical absorption was measured during both darkening and bleaching of the glass. |
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