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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses
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Thermal stability and heat capacity changes at the glass transition in K2O-WO3-TeO2 glasses

机译：K2O-WO3-TeO2玻璃在玻璃化转变时的热稳定性和热容变化

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The thermal stability and heat capacity changes in the glass transition region of K2O-WO3-TeO2 glasses (glass formation range 20-90 mol% TeO2) have been studied to examine the structural relaxation behavior. The glasses with 60-70 mol% TeO2 and with both K2O and WO3 are thermally stable against crystallization. It is proposed from Raman spectral analyses that TeO4 trigonal bipyramids change to TeO3 trigonal pyramids with the addition of K2O and that Te-O-W bonds are formed in the substitution of WO3 for TeO2. Heat capacity changes of Delta C-p = 48-58 J mol(-1) K-1 (Delta C-p = C-pl - C-pg, C-pg and C-pl are the heat capacities of the glasses and supercooled liquids, respectively), and ratios C-pl/C-pg = 1.6-1.8 are obtained for xK(2)O . xWO(3). (100 - 2x)TeO2 glasses. The Delta C-p and C-pl/C-pg increase with decreasing TeO2 content, indicating an increase in thermodynamic fragility with decreasing TeO2 content. But, the kinetic fragility estimated from the activation energy for viscous flow is almost constant irrespective of TeO2 content. These behaviors have been analyzed using the configurational entropy model proposed by Adam and Gibbs. The results indicate that in K2O-WO3-TeO2 glasses, Te-O-Te bonds are weak and bond breakings occur easily in the glass transition region, leading to large configurational entropy changes and thus large Delta C-p. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 32]
机译：研究了K2O-WO3-TeO2玻璃（玻璃形成范围为20-90 mol％TeO2）的玻璃化转变区域的热稳定性和热容变化，以研究其结构弛豫行为。具有60-70摩尔％TeO2以及同时具有K2O和WO3的玻璃对结晶具有热稳定性。根据拉曼光谱分析提出，通过添加K 2 O，TeO 4三角双锥体转变为TeO 3三角锥体，并且在用WO 3代替TeO 2时形成Te-O-W键。 Delta Cp = 48-58 J mol（-1）K-1的热容变化（Delta Cp = C-pl-C-pg，C-pg和C-pl分别是玻璃和过冷液体的热容），则xK（2）O的比率C-pl / C-pg = 1.6-1.8。 xWO（3）。 （100-2x）TeO2眼镜。随着TeO2含量的减少，ΔC-p和C-pl / C-pg会增加，这表明随着TeO2含量的减少，热力学脆性也会增加。但是，由粘性流的活化能估算的动力学脆性几乎恒定，与TeO2含量无关。这些行为已使用Adam和Gibbs提出的构型熵模型进行了分析。结果表明，在K2O-WO3-TeO2玻璃中，Te-O-Te键很弱，并且在玻璃化转变区域中很容易发生键断裂，从而导致较大的结构熵变化，从而使Delta C-p大。 （C）1998 Elsevier Science B.V.保留所有权利。 [参考：32]

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