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首页> 外文期刊>Zeitschrift fur Anorganische und Allgemeine Chemie >Synthesis, characterization, and chemical vapor transport of solid solutions in the MgMoO_4-NiMoO_4 system
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Synthesis, characterization, and chemical vapor transport of solid solutions in the MgMoO_4-NiMoO_4 system

机译：MgMoO_4-NiMoO_4系统中固溶体的合成，表征和化学气相传输

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摘要

Two solid solution series exist in the system MgMoO_4-NiMoO_ 4. The α-Ni__(1-y)Mg_yMoO_4 solution series, isostructural to α-NiMoO_4, is thermodynamically stable at ambient conditions for compositions between 0 % and about 75 % magnesium content. The solution series β-Mg_(1-x)Ni_xMoO_ 4, isostructural to MgMoO_4 and the high temperature β modification of NiMoO_4, is thermodynamically stable at ambient conditions for compositions with < 25 % nickel content. A complete solid solution series β-Mg_(1-x)Ni_xMoO_4 exists at higher temperatures (> 823 K). The transition temperature for the α → β transition decreases with increasing magnesium content. The coexistence of both polymorphs at room temperature in samples with a wide range of composition is a result of the kinetic inhibition of the phase transition β → α. The chemical vapor transport of β-Mg_ (1-x)Ni_xMoO_4 solid solutions with chlorine was investigated. Crystals with a nickel content up to 25 % were synthesized in temperature gradients 1273 K → 1223 K or 1273 K → 1173 K. Deposited nickel richer crystals are destroyed during cooling down to room temperature due to the phase transition. The observed distinctive nickel enrichment during the transport process is in good agreement with predictions by thermodynamic modeling.
机译：MgMoO_4-NiMoO_4系统中存在两个固溶系列。α-Ni__（1-y）Mg_yMoO_4与α-NiMoO_4同构的溶液系列在环境条件下对镁的含量在0％至75％之间是热力学稳定的。对于镍含量小于25％的成分，溶液系列β-Mg_（1-x）Ni_xMoO_ 4，与MgMoO_4等价的结构以及NiMoO_4的高温β修饰在环境条件下是热力学稳定的。完全固溶体系列β-Mg_（1-x）Ni_xMoO_4在较高温度（> 823 K）下存在。 α→β转变的转变温度随镁含量的增加而降低。组成范围很广的样品中两种多晶型物在室温下共存是相变β→α动力学抑制的结果。研究了含氯的β-Mg_（1-x）Ni_xMoO_4固溶体的化学气相迁移。在温度梯度1273 K→1223 K或1273 K→1173 K下合成了镍含量最高为25％的晶体。由于相变，冷却至室温时会破坏沉积的富镍晶体。在运输过程中观察到的独特的镍富集与热力学模型的预测非常吻合。

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