Physical properties of alkaline-earth and alkali borate glasses prepared over an extended range of compositions
Physical properties of alkaline-earth and alkali borate glasses prepared over an extended range of compositions
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DOI：
10.1016/s0022-3093(01)00768-2
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发表时间：
2001-11
影响因子：
3.5
通讯作者：
N. Lower;J. Mcrae;H. Feller;A. R. Betzen;Shalini Kapoor;M. Affatigato;S. Feller
中科院分区：
文献类型：
--
作者：
N. Lower;J. Mcrae;H. Feller;A. R. Betzen;Shalini Kapoor;M. Affatigato;S. Feller
通过使用快速冷却，我们极大地扩展了已报道的二元镁、钙、锶和硼酸钡系统的玻璃形成范围。我们观察到了低碱土氧化物含量的相分离，通常低于约15摩尔%的碱土氧化物，但我们已经能够将玻璃形成的碱土氧化物极限提高到约60-65摩尔%。我们已经确定了这些系统中大量玻璃的密度和玻璃化转变温度。我们将这些数据与基于光谱学的原子排列研究进行了比较。使用从Greenblatt和Bray的核磁共振数据导出的模型。化学。玻璃8(5)(1967)190-193]我们已经确定了被认为存在于每个体系中的四个基本硼酸盐结构单元的相关体积。这些基团包括具有三个(F1)、两个(F3)和一个桥氧(F4)的三角硼以及四面体硼单元(F2)。我们将这些体积与从二元碱性硼酸盐得到的体积进行了比较。此外，我们还利用Shannon半径和Prewitt半径计算了硼酸盐基的体积。这使我们能够确定和比较碱土和碱性硼酸盐体系中每种硼酸盐排列的堆积分数。TGData显示了两个不同的区域，一个是碱土硼酸盐的高温区，一个是碱性硼酸盐的高温区。这些区域之间的距离约为150°C。
By using rapid cooling we have greatly extended the reported glass-forming ranges in the binary magnesium, calcium, strontium, and barium borate systems. We observed phase separation for low alkaline-earth oxide contents, typically below about 15 mol% alkaline-earth oxide, but we have been able to increase the alkaline-earth oxide limit of glass formation to approximately 60–65 mol%. We have determined the density and the glass transition temperature for a large number of glasses within each of these systems. We compare these data with atomic arrangement studies based on spectroscopy. Using a model derived from the NMR data of Greenblatt and Bray [Phys. Chem. Glasses 8 (5) (1967) 190–193] we have determined the associated volumes of the four basic borate structural units thought to be present in each system. These groups include trigonal borons with three (f1), two (f3), and one bridging oxygens (f4) as well as the tetrahedral boron unit (f2). We compare these volumes with those obtained from the binary alkali borates. In addition, we have calculated the volumes of the borate groups using Shannon and Prewitt radii. This allowed us to determine and compare the packing fractions of each borate arrangement in the alkaline-earth and alkali borate systems. The Tgdata display two distinct regions, a high temperature region for the alkaline-earth borates and one for the alkali borates. These regions are separated by approximately 150 °C.