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首页> 外文期刊>Geochimica et Cosmochimica Acta: Journal of the Geochemical Society and the Meteoritical Society >Silicate-phosphate interactions in silicate glasses and melts: II. Quantitative, high-temperature structure of P-bearing alkali aluminosilicate melts
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Silicate-phosphate interactions in silicate glasses and melts: II. Quantitative, high-temperature structure of P-bearing alkali aluminosilicate melts

机译：硅酸盐玻璃和熔体中硅酸盐-磷酸盐的相互作用：II。含P的碱金属铝硅酸盐熔体的定量高温结构

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摘要

Structural data for glasses along the join 0.1[xNa(2)O-(1-x)Al2O3]-0.9SiO(2) + 2 mol.% P2O5, obtained from multinuclear NMR and ab initio shielding calculations, have been combined with Raman spectroscopic data on the glasses at 25 degreesC and melts to temperatures above 1200 degreesC. The structural interpretation of those data is consistent with isolated PO4 and P2O7 complexes together with Q(P)(n) (n = 1-4) species to be present in both glasses and melts. The Q(P)(n) species consist of one PO4 group linked to the silicate network by I to 4 oxygen bridges (corresponding to n = 1-4 in the Q(P)(1) species). The principal solution mechanism of phosphorus in these glasses;md melts can be described with a total of six different schematic expressions. These expressions are consistent with the observation from Si-29 and P-31 MAS-NMR that, for constant P2O5 content, increasing the alumina/alkali ratio leads to a decreased effect of phosphorus on silicate polymerization. Temperature-dependent interactions between phosphate solute and silicate solvent above the glass transition temperature have been identified. The types of interactions were separated into three composition ranges. For peralkaline melts, the phosphate species become more polymerized and the silicate species less polymerized, with increasing temperature: 2PO(4) + Q(Si)(4) double left right arrow P2O7 + Q(Si)(3), and P2O7 + 5Q(Si)(4) double left right arrow 2Q(P)(1) + 3Q(Si)(3), where Q(Si)(n) denotes speciation of silicate and Q(P)(n) speciation of phosphate. The DeltaH for these two reactions are 140 to 190 kJ/mol and similar to 65 kJ/mol, respectively. For compositions near meta-aluminate, the abundance of individual Q(P)(n) species is temperature-dependent at temperatures above the glass transition, 2Q(P)(3) double left right arrow Q(P)(2) + Q(P)(4), with DeltaH = 13 to 19 kJ/mol. The abundance of silicate species is not affected by temperature for those compositions. For peraluminous melts, the phosphate species become less polymerized and the silicate species more polymerized with increasing temperature above the glass transition, Q(P)(4) + Q(Si)(3) double left right arrow Q(P)(3) + 2Q(Si)(4), with DeltaH = 13 to 23 kJ/mol. The structural data obtained in the high-temperature regime indicate that the melt structures resemble those of the glasses, although the abundance of individual melt species is temperature-dependent. Therefore, for peralkaline and peraluminous melts, properties that depend on melt polymerization become more pronounced if melt data, rather than structural data of glasses, were employed. For compositions near meta-aluminate, where neither phosphate nor silicate polymerization varies with temperature, properties that depend on melt polymerization are likely less sensitive to temperature. Copyright (C) 2001 Elsevier Science Ltd. [References: 27]
机译：从多核NMR和从头算屏蔽计算获得的沿连接[0.1 [xNa（2）O-（1-x）Al2O3] -0.9SiO（2）+ 2 mol。％P2O5的玻璃的结构数据已与拉曼结合在25摄氏度时眼镜上的光谱数据，并融化到1200摄氏度以上的温度。这些数据的结构解释与玻璃和熔体中都存在的孤立的PO4和P2O7配合物以及Q（P）（n）（n = 1-4）种一致。 Q（P）（n）物种由一个通过I至4个氧桥与硅酸盐网络相连的PO4基团组成（对应于Q（P）（1）物种中的n = 1-4）。这些玻璃中的磷的主要溶解机理; md熔体可以用总共六个不同的示意图表示。这些表达式与Si-29和P-31 MAS-NMR的观察结果一致，对于恒定的P2O5含量，增加氧化铝/碱金属比会导致磷对硅酸盐聚合的影响降低。已经确定了高于玻璃化转变温度的磷酸盐溶质和硅酸盐溶剂之间的温度依赖性相互作用。相互作用的类型分为三个组成范围。对于高碱性熔体，随着温度的升高，磷酸盐物质变得更加聚合，而硅酸盐物质变得更少聚合：2PO（4）+ Q（Si）（4）左向右箭头P2O7 + Q（Si）（3）和P2O7 + 5Q（Si）（4）左双向右箭头2Q（P）（1）+ 3Q（Si）（3），其中Q（Si）（n）表示硅酸盐的形态，Q（P）（n）磷酸盐的形态。这两个反应的DeltaH分别为140至190 kJ / mol，与65 kJ / mol相似。对于偏铝酸盐附近的成分，单个Q（P）（n）种类的丰度在高于玻璃化转变温度2Q（P）（3）时向左取决于双Q（P）（2）+ Q （P）（4），DeltaH = 13至19 kJ / mol。对于那些组合物，硅酸盐种类的丰度不受温度的影响。对于高铝熔体，随着玻璃化转变温度以上的温度升高，磷酸盐物质变得较少聚合，硅酸盐物质变得更加聚合，Q（P）（4）+ Q（Si）（3）double left right right Q（P）（3） + 2Q（Si）（4），DeltaH = 13至23 kJ / mol。在高温状态下获得的结构数据表明，熔体的结构类似于玻璃的熔体，尽管单个熔体种类的丰度与温度有关。因此，对于高碱性和高铝熔体，如果采用熔体数据而非玻璃的结构数据，则取决于熔体聚合的性能会变得更加明显。对于偏铝酸盐附近的组合物，其中磷酸盐和硅酸盐的聚合都不随温度变化，取决于熔融聚合的性质可能对温度不太敏感。版权所有（C）2001 Elsevier Science Ltd. [引用：27]

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