Solid solution phases from thermally crystallized Li2O-MgO-Al2O3-SiO2 glasses |
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Authors: | S.M. Salman A.A. Omar S.N. Salama |
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Affiliation: | Glass Research Laboratory, National Research Centre, Dokki, CairoEgypt;X-Rays Division, Central Services Laboratory, National Research Centre, Dokki, CairoEgypt |
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Abstract: | Phase transformations have been studied in glasses related in composition to Li2O-MgO-SiO2 (930° C) eutectic glass modified by replacement on a cation per cation basis. Crystallization processes and changes in the solid solutions of the mineral phases developed during the controlled heating of the glasses have been followed using X-ray and microscopic techniques.Solid solutions of lithia aluminosilicate phases (B-eucryptite and/or B-spodumene s.s.) are the essential minerals that crystallize in glasses through most of the heat treatment applied. Lithium metasilicate, disilicate, clinoenstatite and cordierite are also encountered.B-eucryptite s.s. is formed in early stage of crystallization of the glass which transforms into B-spodumene s.s. at higher temperature (800° C). However, in some cases, it persists at temperatures as high as 1000° C.Metastable B-eucryptite-B-quartz s.s. can accomodate considerable amounts of Mg2+ and Al3+ ions in its lattice especially at lower temperature. At higher temperature for long duration, a redistribution of the elements takes place, and the cordierite phase then developed. |
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