High Temperature Thermoelectric Properties of the Solid-Solution Zintl Phase Eu11Cd6鈥?i>xZnxSb12

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• 作者：Nasrin Kazem ; Antonio Hurtado ; Fan Sui ; Saneyuki Ohno ; Alexandra Zevalkink ; Jeffrey G. Snyder ; Susan M. Kauzlarich
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：June 23, 2015
• 年：2015
• 卷：27
• 期：12
• 页码：4413-4421
• 全文大小：452K
• ISSN：1520-5002

文摘

Solid-solution Zintl compounds with the formula Eu₁₁Cd_6鈥?i>xZn_xSb₁₂ have been synthesized from the elements as single crystals using a tin flux according to the stoichiometry Eu:Cd:Zn:Sb:Sn of 11:6鈥?i>x_p:x_p:12:30 with x_p = 0, 1, 2, 3, 4, 5, and 6, where x_p is the preparative amount of Zn employed in the reaction. The crystal structures and the compositions were established by single-crystal as well as powder X-ray diffraction and wavelength-dispersive X-ray analysis measurements. The title solid-solution Zintl compounds crystallize isostructurally in the centrosymmetric monoclinic space group C 2/m (No. 12, Z = 2) as the Sr₁₁Cd₆Sb₁₂ structure type (Pearson symbol mC58). There is a miscibility gap at 3 鈮?x_p 鈮?4 where the major product crystallizes in a disordered structure related to the Ca₉Mn₄Bi₉ structure type; otherwise, for all other compositions, the Sr₁₁Cd₆Sb₁₂ structure is the majority phase. Eu₁₁Cd₆Sb₁₂ shows lower lattice thermal conductivity relative to Eu₁₁Zn₆Sb₁₂ consistent with its higher mean atomic weight, and as anticipated, the solid-solution samples of Eu₁₁Cd_6鈥?i>xZn_xSb₁₂ have effectively reduced lattice thermal conductivities relative to the end member compounds. Eu_11.0(1)Cd_4.5(2)Zn_1.5(2)Sb_12.0(1) exhibits the highest zT value of >0.5 at around 800 K which is twice as large as the end member compounds.