The glass transition temperature of silicate and borate glasses
The glass transition temperature of silicate and borate glasses
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DOI：
10.1016/j.jnoncrysol.2005.01.044
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发表时间：
2005-03-15
影响因子：
3.5
通讯作者：
Penkov, I
中科院分区：
文献类型：
--
作者：
Avramov, I;Vassilev, T;Penkov, I
讨论了玻璃化转变温度对硅酸盐组合物和硼酸盐组合物的依赖性。结合文献资料，对硼硅酸盐玻璃釉的一些新的实验结果进行了整理。结果表明，在玻璃化转变区间内，粘流活化能E（T-g）与玻璃化转变温度有关。粘性流动的活化能由E（T-g）= 260 T（g）+/- 10% [J/mol]给出。在硅酸盐的情况下，玻璃化转变温度几乎与网络改性剂的摩尔分数x呈线性下降，NM。在0.01 < x < 0.6的区间内，玻璃化转变温度为：T-g（x）=（1080 - 626 x）+/- 5% [K]对于（Na 2 O + MgO）（x）（Al 2 O3 + SiO2）（1-x）T-g（x）=（967 - 626 x）+/- 5% [K]对于（PbO）（x）（SiO2）（1-x）T-g（x）=（895 - 626 x）+/- 5% [K]对于（Na 2 O）（x）（SiO2）（1-x）这很容易解释，假设粘性流动是由一个氧桥已经断裂的SiO 4四面体的运动控制的。同时，碱性阳离子施加一些空间位阻，因此，阳离子越大，位阻越高。硼酸盐的玻璃化转变温度的组成x依赖性更复杂。它具有约30%的网络改性剂的最大值。这是因为NM的引入改变了硼酸盐结构，从由共享边缘的BO 3三角形组成的结构变为与硅酸盐中的SiO 4四面体类似的BO 4四面体。(c)2005 Elsevier B. V.保留所有权利。
The dependence of the glass transition temperature on silicate composition as well as on borate composition is discussed. Some new experimental results on borosilicate glass-enamels are put together with the existing literature data. It is demonstrated that in the glass transition interval the activation energy E(T-g) for viscous flow is related to the glass transition temperature. The activation energy for viscous flow is given by E(T-g) = 260T(g) +/- 10% [J/mol]. In the case of silicates, the glass transition temperature decreases almost linearly with the molar fraction x of network modifier, NM. In the interval 0.01 < x < 0.6 the glass transition temperature is:T-g(x) = (1080 - 626x) +/- 5% [K] for (Na2O + MgO)(x)(Al2O3 + SiO2)(1-x)T-g(x) = (967 - 626x) +/- 5% [K] for (PbO)(x)(SiO2)(1-x)T-g(x) = (895 - 626x) +/- 5% [K] for (Na2O)(x)(SiO2)(1-x)This is easily explained assuming that viscous flow is controlled by the motion of SiO4 tetrahedra with one oxygen bridge already broken. In the same time the alkaline cations impose some spatial hindrance, therefore, larger is the cation the higher is the hindrance. The composition, x, dependence of the glass transition temperature of borates is more complicated. It has a maximum at about 30% of network modifier. This happens because introduction of NM changes borate structure from one consisting of BO3 triangles sharing edges to BO4 tetrahedra similar to SiO4 tetrahedra in silicates. (c) 2005 Elsevier B.V. All rights reserved.