Nickel deficiency in RE

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• 作者：Svilen Bobev< ; lk type=""email"" key=""bobev@udel.edu""> ; Sheng-qing Xia ; Eric D. Bauer ; Filip Ronning ; Joe D. Thompson ; John L. Sarrao
• 关键词：PrNi₂P₂ ; CeNi₂P₂ ; Crystal structure ; Single-crystal X-ray diffraction ; Structural disorder
• 刊名：Journal of Solid State Chemistry
• 出版年：2009
• 出版时间：June 2009
• 年：2009
• 卷：182
• 期：6
• 页码：1473-1480
• 全文大小：492 K

文摘

Large single crystals from RENi_2–xP₂ (RE=La, Ce, Pr) were synthesized from the pure elements using Sn as a metal flux, and their structures were established by X-ray crystallography. The title compounds were confirmed to crystallize in the body-centered tetragonal ThCr₂Si₂ structure type (space group I4/mmm (No. 139); Pearson's symbol tI10), but with a significant homogeneity range with respect to the transition metal. Systematic synthetic work, coupled with accurate structure refinements indicated strong correlation between the degree of Ni-deficiency and the reaction conditions. According to the temperature dependent dc magnetization measurements, LaNi_2–xP₂ (x=0.30(1)), as expected, is Pauli-like paramagnetic in the studied temperature regime, while the Ce-analog CeNi_2–xP₂ (x=0.28(1)) shows the characteristics of a mixed valent Ce³⁺/Ce⁴⁺ system with a possible Kondo temperature scale on the order of 1000 K. For three different PrNi_2–xP₂ (x0.5) samples, the temperature and field dependence of the magnetization indicated typical local moment 4f-magnetism and a stable Pr³⁺ ground state, with subtle variations of T_C as a function of the concentration of Ni defects. Field-dependent heat capacity data for CeNi_2–xP₂ (x=0.28(1)) and PrNi_2–xP₂ (x=0.53(1)) are discussed as well.