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首页> 外文期刊>European Journal of Glass Science and Technology, PartB. Physics and Chemistry of Glasses >Borophosphosilicate glasses: properties and structure
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Borophosphosilicate glasses: properties and structure

机译：硼磷硅玻璃：特性和结构

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摘要

The properties and structure of xB_2O_3:30-xP_2O_5:70SiO_2 glasses, where x = 0, 2.5 ,5, 7.5, 10, 15, 20, 22.5, 25,27.5 and 30 are examined. In order to minimise P volatilisation losses, ternary glasses were synthesised from mixtures of previously prepared 30P_2O_5:70SiO_2 and 30B_2O_3:70SiO_2 glasses. Chemical analysis confirmed that analysed compositions were within 0.5 percent of nominal values. Although the glass transition temperature (T_g) of the binary P, B silicate glass is 600, 440 deg C, respectively, T_g of ternary glasses attains a maximum value of 695 deg C for intermediate compositions containing approx 12.5 percent B_2O_3. The compositional dependence of the thermal expansion coefficient and refractive index of these glasses is also discontinuous at B/P-1. Structural characterisation was carried out using wideline, magic angle spinning (MAS) and triple quantum MAS NMR spectroscopic techniques. A very small percentage (<= 3 percent) of the total Si is present as both 5- and 6-fold coordinated species in the most P-rich glasses. ~(31)P wideline NMR spectra of the same glasses show an asymmetric lineshape characteristic of an axially symmetric O=PO_(3/2) species, whereas the spectra of B-rich glasses show only the Gaussian resonance typical of symmetric PO_(4/2) tetrahedra. ~(11)B results indicate that, as B is progressively replaced by P, B coordination changes monotonically from fully trigonal to dominantly tetrahedral, with the tetrahedral B fraction ranging from 80 to 95 percent for the most P-rich glasses. Overall the results are consistent with a structural scenario of associated BO_(4/2) and PO_(4/2) tetrahedra comprising a fully polymerised silica-like network for the glasses of intermediate composition. The greater degree of network connectivity caused by the preferential association of B and P to form BPO_4-like groups is the likely origin of the T_g maximum.
机译：研究了xB_2O_3：30-xP_2O_5：70SiO_2玻璃的性质和结构，其中x = 0、2.5、5、7.5、10、15、20、22.5、25、27.5和30。为了使P挥发损失最小，从先前制备的30P_2O_5：70SiO_2和30B_2O_3：70SiO_2玻璃的混合物中合成了三元玻璃。化学分析证实分析的组成在标称值的0.5％以内。尽管二元P，B硅酸盐玻璃的玻璃化转变温度（T_g）分别为600、440℃，但对于含约12.5％B_2O_3的中间组合物，三元玻璃的T_g达到最大值695℃。这些玻璃的热膨胀系数和折射率的成分依赖性在B / P-1处也是不连续的。使用宽线，魔角旋转（MAS）和三重量子MAS NMR光谱技术进行结构表征。在大多数富含P的玻璃中，Si的极小百分比（<= 3％）作为5倍和6倍配位物种存在。相同玻璃的〜（31）P宽线NMR光谱显示了轴对称O = PO_（3/2）物种的不对称线形特征，而富含B的玻璃的光谱仅显示了对称PO_（4）的典型高斯共振。 / 2）四面体。 〜（11）B结果表明，随着B逐渐被P取代，B的配位从完全三角变为占优势的四面体，对于大多数富含P的玻璃，四面体B的比例在80％到95％之间。总体而言，结果与相关的BO_（4/2）和PO_（4/2）四面体的结构方案一致，其中BO_（4/2）和PO_（4/2）四面体包含用于中间成分玻璃的完全聚合的二氧化硅样网络。由B和P优先关联形成BPO_4样基团引起的更大程度的网络连接性可能是T_g最大值的起源。

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