Metallic properties of Ba₂Cu₃P₄ and BaCu₂Pn₂ (Pn=As, Sb)

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• 作者：Bayrammurad Saparov ; ^{saparovbi@ornl.gov} ; Athena S. Sefat
• 关键词：Copper pnictide ; Polymorphism ; Thermal conductivity ; Crystal structure ; Superconductivity
• 刊名：Journal of Solid State Chemistry
• 出版年：2012
• 期刊代码：130_00224596
• 类别：ch
• 出版时间：July, 2012
• 卷：191
• 期：Complete
• 页码：213-219
• 文件大小：733 K

摘要

We report the synthesis of ternary barium copper pnictides, Ba₂Cu₃P₄ and BaCu₂Pn₂ (Pn=As, Sb), and their structural, magnetic, and transport properties. They all crystallize in different structures shown by X-ray diffraction, although their structures reveal close relations. The body-centered tetragonal BaCu₂As₂ adopts ThCr₂Si₂-type (I4/mmm) structure, whereas Ba₂Cu₃P₄ is a copper-deficient derivative of this phase, crystallizing in the body-centered orthorhombic space group, Ibam. There are two polymorphs of BaCu₂Sb₂: 伪-BaCu₂Sb₂ that adopts CaBe₂Ge₂-type structure; 尾-BaCu₂Sb₂ that is a 2:1 combination of CaBe₂Ge₂- and ThCr₂Si₂-type structural segments. All phases are metallic and non-magnetic. The room temperature thermal conductivity for polycrystalline BaCu₂As₂ is 鈮?2 W/(m K) and the Seebeck coefficient is 鈮?15 渭V/K, which result in a small (鈮?.03) thermoelectric figure of merit.