Ca1鈥?i>xRExAg1鈥?i>ySb (RE = La, Ce, Pr, Nd, Sm; 0 鈮?x 鈮?; 0 鈮?y 鈮?): Interesting Structural Transformation and Enhanced High-Temperature T

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• 作者：Jian Wang ; Xiao-Cun Liu ; Sheng-Qing Xia ; Xu-Tang Tao
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：August 14, 2013
• 年：2013
• 卷：135
• 期：32
• 页码：11840-11848
• 全文大小：492K
• 年卷期：v.135,no.32(August 14, 2013)
• ISSN：1520-5126

文摘

For materials used in high-temperature thermoelectric power generation, the choices are still quite limited. Here we demonstrate the design and synthesis of a new class of complex Zintl compounds, Ca_1鈥?i>xRE_xAg_1鈥?i>ySb (RE = La, Ce, Pr, Nd, Sm) (P6₃mc, No. 186, LiGaGe-type), which exhibit a high figure of merit in the high-temperature region. Compared with the parent structure that is based on CaAgSb (Pnma, No. 62, TiNiSi-type), an interesting structural relationship is established which suggests that important size and electronic effects govern the formation of these multinary phases. According to theoretical calculations, such a structural transformation from the orthorhombic TiNiSi-type to the hexagonal LiGaGe-type also corresponds to an obvious modification in the electronic band structure, which explains the observed significant enhancement of the related thermoelectric properties. For an optimized p-type material, Ca_0.84Ce_0.16Ag_0.87Sb, a figure of merit of 0.7 can be achieved at 1079 K, which is comparable to that of Yb₁₄MnSb₁₁ at the same temperature. In addition, due to the excellent thermal stability and high electrical conductivity, these materials are very promising candidates for high-temperature thermoelectric power generation.