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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >High-temperature calorimetric study of glass-forming fluorozirconates
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High-temperature calorimetric study of glass-forming fluorozirconates

机译：形成玻璃的氟锆酸盐的高温量热研究

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Using high temperature calorimetric techniques, enthalpies of mixing of melts, enthalpies of formation of glasses and enthalpies of formation of crystals have been measured in binary systems ZrF4-BaF2, ZrF4-NaF, ZrF4-LaF3 and selected compositions in the system ZrF4-BaF2-LaF3-AlF3-NaF. The system ZrF4-LaF3 shows essentially zero enthalpies of mixing of melts. In the other systems, then are strongly exothermic enthalpies of mixing. In the binary systems ZrF4-BaF2 and ZrF4-NaF, the enthalpy of mixing of melts and the enthalpy of formation of crystals show minima at the same compositions, Ba2ZrF8 and Na3ZrF7, respectively, indicating the stoichiometric complexes ZrF84- and ZrF73-. These results are discussed in relation to energetics, structure, speciation and acid-base chemistry and suggest the following: ZrF4, LaF3 and AlF3 are anionic complex-formers, while BaF2 and NaF are ionized in the molten state. The coordination number of the zirconium fluoride anionic complex varies with the amount of alkali or alkaline earth fluoride. A model is proposed in which glass-forming melts are dominated by ZrF5- species and lie near deep eutectics. Therefore, glass formation in fluorozirconates involves a substantial structural change, which is dominated by short-range atomic arrangements, from the melt with predominantly ZrF5- to the glass where zirconium is 7 or 8 coordinated by fluorine. (C) 1997 Elsevier Science B.V.
机译：使用高温量热技术，已在二元体系ZrF4-BaF2，ZrF4-NaF，ZrF4-LaF3中测量了熔体混合焓，玻璃形成焓和晶体形成焓，以及在ZrF4-BaF2-系统中选择了某些成分。 LaF3-AlF3-NaF。 ZrF4-LaF3系统显示出熔体混合焓基本上为零。在其他系统中，则是强烈的放热混合焓。在二元体系ZrF4-BaF2和ZrF4-NaF中，熔体混合焓和晶体形成焓在相同的组成Ba2ZrF8和Na3ZrF7处分别显示出最小值，表明化学计量的配合物ZrF84-和ZrF73-。讨论了有关能量，结构，形态和酸碱化学的这些结果，并提出以下结论：ZrF4，LaF3和AlF3是阴离子络合物形成剂，而BaF2和NaF在熔融状态下被电离。氟化锆阴离子络合物的配位数随碱金属或碱土金属氟化物的量而变化。提出了一个模型，其中形成玻璃的熔体受ZrF5物种支配，并位于深共晶附近。因此，氟锆酸盐中的玻璃形成涉及从短程原子排列起主要的结构变化，从主要是ZrF5的熔体到锆是7或8的氟配位的玻璃。 （C）1997年Elsevier Science B.V.

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