The role of coordination and valance states of tungsten ions on some physical properties of Li₂O–Al₂O₃–ZrO₂–SiO₂ glass system

详细信息    查看全文

• 作者：Ch. Srinivasa Rao^a ; V. Ravikumar^a ; T. Srikumar^a ; Y. Gandhi^a ; N. Veeraiah ; ^a ; ^{nvr8@rediffmail.com"" rel=""nofollow}
• 关键词：Li₂O– ; Al₂O₃– ; ZrO₂– ; SiO₂ glasses ; Tungsten ions ; Spectroscopic properties ; Dielectric properties
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2011
• 出版时间：August 2011
• 年：2011
• 卷：357
• 期：16-17
• 页码：3094-3102
• 全文大小：822 K

文摘

A series of Li₂O–Al₂O₃–ZrO₂–SiO₂ glasses doped with different concentrations of WO₃ (0 to 5.0 mol. % ) have been synthesized. Differential thermal analysis of the samples indicated increasing glass forming ability with the increasing concentration of WO₃ in the glass matrix. A variety of spectroscopic (optical absorption, IR, Raman and ESR) and dielectric properties (over a range of frequency and temperature) of these glasses have been investigated. The optical absorption and ESR spectral studies have pointed out that a part of tungsten ions do exist in W⁵⁺ state in addition to W⁶⁺ state especially in the samples containing low concentration of WO₃. The IR and Raman spectral studies have suggested that there is a decreasing degree of disorder in the glass network with increase in the concentration of WO₃. The values of dielectric parameters viz., dielectric constant, loss and ac conductivity at any frequency and temperature are observed to decrease as the concentration of WO₃ is increased. Such changes have been attributed to decrease of redox ratio or decreasing proportions of W⁵⁺ ions that act as modifiers in the glass network. The quantitative analysis of the results of ac conductivity and dielectric properties have indicated an increase in the insulating character of the glasses with the concentration of WO₃; this is attributed to the presence of tungsten ions largely in W⁶⁺ ions that participate in the glass network forming with WO₄ structural units.