Valence and Structural Transitions in the Pseudo-Ternary Germanide Ce(Rh0.69Ir0.31)Ge

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• 作者：Etienne Gaudin ; Bernard Chevalier ; Birgit Heying ; Ute Ch. Rodewald ; and Rainer P&ouml ; ttgen
• 刊名：Chemistry of Materials
• 出版年：2005
• 出版时间：May 17, 2005
• 年：2005
• 卷：17
• 期：10
• 页码：2693 - 2700
• 全文大小：283K
• 年卷期：v.17,no.10(May 17, 2005)
• ISSN：1520-5002

文摘

Ce(Rh_0.69Ir_0.31)Ge has been investigated by magnetization measurements, differential scanningcalorimetry, and X-ray diffraction on a single crystal at 300, 150, and 100 K. For the first time, a decreaseof the valence of cerium with decreasing temperature has been observed. This first-order valence transitionevidenced at 236-258 K by magnetization measurements is correlated to the occurrence of a structuraltransition appearing between 300 and 150 K. The structural properties versus temperature of Ce(Rh_0.69Ir_0.31)Ge are discussed in relation to those determined on single crystals on the antiferromagnet CeRhGeand on the intermediate valence compound CeIrGe. The structure refinements revealed significantlydifferent distortions for the [RhGe] and [IrGe] polyanionic networks, which are a direct consequence ofthe different electron densities at the rhodium and iridium sites, respectively. The crystal chemicalpeculiarities of the CeRhGe, Ce(Rh_0.69Ir_0.31)Ge, and CeIrGe structures are discussed.