Chethana, B K and Reddy, C Narayana and Rao, K J (2012) Thermo-physical and structural studies of sodium zinc borovanadate glasses in the region of high concentration of modifier oxides. In: MATERIALS RESEARCH BULLETIN, 47 (7). pp. 1810-1820.
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This paper reports investigation of Na2O and ZnO modified borovanadate glasses in the highly modified regime of compositions. These glasses have been prepared by microwave route. Ultraviolet (UV) and visible, infrared (IR), Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) and Electron Paramagnetic Resonance (EPR) spectroscopies have been used to characterize the speciation in the glasses. Together with the variation of properties such as molar volume and glass transition temperatures, spectroscopic data indicate that at high levels of modification, ZnO tends to behave like network former. It is proposed that the observed variation of all the properties can be reasonably well understood with a structural model. The model considers that the modification and speciation in glasses are strongly determined by the hierarchy of group electronegativities. Further, it is proposed that the width of the transitions of glasses obtained under same condition reflects the fragility of the glasses. An empirical expression has been suggested to quantify fragility on the basis of width of the transition regions. (C) 2012 Elsevier Ltd. All rights reserved.
|Item Type:||Journal Article|
|Additional Information:||Copy right for this article belongs to Elsevier B.V.|
|Keywords:||Glasses;Nuclear magnetic resonance;Differential scanning calorimetry;Specific heat|
|Department/Centre:||Division of Chemical Sciences > Solid State & Structural Chemistry Unit|
|Date Deposited:||14 Jul 2012 08:10|
|Last Modified:||14 Jul 2012 08:10|
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