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首页> 外文期刊>European Journal of Glass Science and Technology, PartB. Physics and Chemistry of Glasses >Crystalline borosilicates of alkali and alkaline earth metals: hierarchy, fundamental building blocks and thermal expansion
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Crystalline borosilicates of alkali and alkaline earth metals: hierarchy, fundamental building blocks and thermal expansion

机译：碱和碱土金属的结晶硼酸盐：等级，基本构建块和热膨胀

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摘要

A brief review is presented of the structure hierarchy, main fundamental building blocks (FBBs) and some thermal characteristics of crystalline alkali and alkaline earth borosilicates. Low-dimensional borosilicate anions are typical for borosilicates with considerable contents of non-tetrahedrally coordinated cations. There are only six types of borosilicate anions containing boron in BO3 triangles, which are almost never connected to silicon tetrahedra. The lower the ratio "non-tetrahedral/tetrahedral cation", the higher the dimension of the layered and framework anions that form. Most Si-dominant borosilicates (B/Si <= 1) with a low content of non-tetrahedrally coordinated cations have 3D framework structures formed by boron and silicon atoms in tetrahedral coordination only. As with aluminosilicates, 3D-borosilicate structures contain a great variety of rings of tetrahedra, which are the main FBBs of borosilicate structures. The most common rings of tetrahedra are 4-, 6- and 8-membered. An ordered distribution of Si and B is typical for borosilicates. There are many OH-containing borosilicates, especially among the structures with 0D-, 1D- and 2D-anions; conversely, they almost never have H2O molecules in the crystal structure. OH-groups are often involved in the coordination of boron. Non-tetrahedral alkali and alkaline earth cations are coordinated by oxygen or hydroxyl groups with usual coordination numbers: lithium is 4-coordinated, sodium is mostly 6-coordinated, and 8-coordination is typical for calcium. Other large cations have irregular coordinations with more than eight oxygen atoms. Thermal expansion coefficients (TECs) determined for 31 natural and synthetic compounds have relatively low values independent of the dimensionality of the structure. The linear TECs of crystals are slightly higher than those of glasses of corresponding composition; the average values are 10x10(-6) and 8x10(-)(6) degrees C-1 for crystals and glasses, respectively.
机译：简要介绍了结构层次结构，主要基本构建块（FBBS）以及结晶碱和碱土硼酸盐的一些热特性。低维硼硅酸盐阴离子是硼硅酸盐的典型，具有相当大的非四面体配位阳离子。只有六种类型的硼硅酸盐阴离子含有硼在Bo3三角形中的硼，几乎从未连接到硅Tetrahedra。比率“非四面体/四面体阳离子”的比例越低，形式的层状和框架阴离子的尺寸越高。具有低含量的非四面体协调阳离子的大多数Si-占优势硼硅酸盐（B / Si <= 1）具有仅由硼和硅原子形成的3D框架结构，仅在四面体配位中形成。与硅硅酸盐一样，3D-硼硅酸盐结构含有各种各样的四面体环，这是硼硅酸盐结构的主要FBBS。 Tetrahedra最常见的环是4-，6-和8元。 Si和B的有序分布对于硼硅酸盐是典型的。含有许多含OH的硼硅酸盐，尤其是具有0d-，1d-和2d阴离子的结构;相反，它们几乎从未在晶体结构中具有H2O分子。 OH-GROUP往往涉及硼的协调。非四面体碱和碱土阳离子由氧气或羟基配位，常规配位数量：4配位，钠主要是6-协调，钙的8-配位是钙的典型。其他大型阳离子具有超过八个氧原子的不规则配位。为31种天然和合成化合物测定的热膨胀系数（TECS）具有与结构的维度无关的相对低的值。晶体的线性TECs略高于相应组成的眼镜;对于晶体和玻璃，平均值为10×10（-6）和8×10（ - ）（6）摄氏度C-1。

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