Raman scattering study of barium borate glasses and melts
Raman scattering study of barium borate glasses and melts
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DOI：
10.1016/j.jpcs.2013.02.014
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发表时间：
2013-07
影响因子：
4
通讯作者：
A. Osipov;L. Osipova
中科院分区：
文献类型：
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作者：
A. Osipov;L. Osipova
制备了xBaO-（100-x）B2 O3（x=20，25，30，35，40，45，50，55，60和67摩尔%）组成的玻璃和熔体，并用高温拉曼光谱进行了研究。结果表明，玻璃态和熔融态样品在氧化钡浓度相对较低（x=20-35mol%）时的结构由[B <$4]−带电四面体（B <$4是桥氧原子）、B <$2O −不对称三角形（O−是非桥氧原子）和B <$3中性单元组成。[B 4]−四面体（N4）的浓度随熔体中BaO含量的增加而单调降低，而在玻璃态样品中，N4在x ≤ 40mol%时出现最大值。 【配方：当x≥ 40mol%时，熔体结构中出现了焦硼酸根结构单元，当x=60和67mol%时，熔体结构中也形成了正硼酸根阴离子。由温度变化产生的结构重组的主要机制取决于熔体组成。短程有序（SRO）结构的变化可以用25<x<40时的[B 4]−惠B 2 O −异构化反应来描述，而x>50时熔体中结构单元之间的动态平衡最有可能用[式：见正文]异构化反应来描述。在这两种情况下，随着温度的升高，平衡向右移动。低浓度氧化钡（x≤20mol%）熔体的局部结构没有明显变化。
Glasses and melts of xBaO–(100−x)B2O3(x=20, 25, 30, 35, 40, 45, 50, 55, 60 and 67mol%) composition have been prepared and studied using high-temperature Raman spectroscopy. It was shown that the structure of the glassy and molten samples with relatively low concentrations of barium oxide (x=20–35mol%) consists of [B∅4]−charged tetrahedra (∅ is a bridging oxygen atom), B∅2O−asymmetric triangles (O−is a non-bridging oxygen atom) and B∅3neutral units. The concentration of [B∅4]−tetrahedra (N4) monotonously decreases with increasing BaO content in the melts structure, whereas N4demonstrates a maximum at x≈40mol% in the glassy samples. [Formula: see text] pyroborate units appear at x≥40mol%, and [Formula: see text] orthoborate anions are also formed in the melts structure when x=60 and 67mol%. The dominant mechanisms for the structural reorganizations generated by changes in temperature depend on the melt composition. The changes in the short range order (SRO) structures can be described by the [B∅4]−⇔B∅2O−isomerization reaction at 25<x<40, whereas the dynamic equilibrium between structural units in the melts with x>50 is most likely described by the [Formula: see text] disproportionation reaction. In both cases, the equilibrium shifts to the right with an increase in temperature. Significant changes in the local structures of melts with a low concentration of barium oxide (x≤20mol%) were not found.