Spectroscopy and structural state of V4+ ions in lithium aluminosilicate glass and glass-ceramics

The optical property of LAS glass and the structural states of V4+ ions were studied by use of kinds of spectra (UV-visible, IR, Raman and EPR) in LAS glass and glass-ceramics containing V2O5. It was found that the V4+ ions formed by reduction of V5+ ions, and existed as the VO2+ complex in octahedral coordination with a tetragonal compression with C-4v symmetry in LAS glass. Additionally, the V4+ ions partially replaced Li+ and occupied tetrahedral sites in beta-quartz solid solution crystal phase. The color of the glasses drastically changed from light yellow-green to claret during crystallization. and the optical absorption in visible range attribute to the transitions of B-2(2g) -> B-2(1g) and B-2(2g) -> E-2(g) of V4+ ions in high crystal field, which was affected by the above structural variation of V4+. Moreover, the addition of V2O5 in LAS glass decreased crystallization temperature of main beta-quartz solid solution crystal phase. (C) 2009 Elsevier B.V. All rights reserved.