The systems YbAu2-xGex and CaAu2-xGex with 0.7<x<1.3 were structurally examined by X-rays on powders and single crystals. In this range of composition nine phases occur, belonging to six closely related structure types: CeCu2, AlB2, EuAuGe (occupation derivative), SrAgGe, α-YbAuGe and β-YbAuGe (the last two being centrosymmetric variants of the CaCuGe type). The equiatomic compound CaAuGe shows a phase transition at 1238 K. YbAuGe crystallizes in three different structural modifications as a function of temperature: α-YbAuGe up to 1003 K, β-YbAuGe in the range 1003 to 1308 K and γ-YbAuGe at T>1308 K. Resistance measurements carried out in the range 14-400 K for the high-temperature forms of YbAuGe and CaAuGe show normal metallic behaviour. Magnetic susceptibility data of YbAuGe are in agreement with the occurrence of divalent ytterbium. © 1998 Elsevier Science S.A.
Phases around the 1:1:1 composition in the Yb-Au-Ge and Ca-Au-Ge systems
PANI, MARCELLA;CANEPA, FABIO MICHELE;
1998-01-01
Abstract
The systems YbAu2-xGex and CaAu2-xGex with 0.7<x<1.3 were structurally examined by X-rays on powders and single crystals. In this range of composition nine phases occur, belonging to six closely related structure types: CeCu2, AlB2, EuAuGe (occupation derivative), SrAgGe, α-YbAuGe and β-YbAuGe (the last two being centrosymmetric variants of the CaCuGe type). The equiatomic compound CaAuGe shows a phase transition at 1238 K. YbAuGe crystallizes in three different structural modifications as a function of temperature: α-YbAuGe up to 1003 K, β-YbAuGe in the range 1003 to 1308 K and γ-YbAuGe at T>1308 K. Resistance measurements carried out in the range 14-400 K for the high-temperature forms of YbAuGe and CaAuGe show normal metallic behaviour. Magnetic susceptibility data of YbAuGe are in agreement with the occurrence of divalent ytterbium. © 1998 Elsevier Science S.A.
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