Phase Transitions, Structure Evolution, and Thermoelectric Properties Based on A2MnSb2 (A = Ca, Yb)
Phase Transitions, Structure Evolution, and Thermoelectric Properties Based on A2MnSb2 (A = Ca, Yb)
复制标题
基于 A2MnSb2 (A = Ca, Yb) 的相变、结构演变和热电性能
DOI：
10.1021/acs.chemmater.1c03527
复制
发表时间：
2021
影响因子：
8.6
通讯作者：
Sheng-Qing Xia
中科院分区：
文献类型：
--
作者：
Kefeng Liu;Jian Liu;Qian Liu;Qiqi Wang;Fan Yu;Xiao-Cun Liu;Sheng-Qing Xia
层状结构可以促进“声子-玻璃-电子-晶体（PGEC）”特性，这对于设计最先进的热电材料至关重要。本文首次发现了ca2mnsb2和Yb2MnSb2两种层状结构的含mn亚稳Zintl相。它们的结构与LiZnSb的结构是同型的，过渡金属位部分占据。有趣的是，这些化合物具有非常广泛的均匀性范围，这使得在Mn位点上可以灵活地调谐。此外，通过相探测证实了Yb9Mn4+ xsb9系与先前报道的Yb9Mn4+ xsb9系的密切关系，退火后实验观察到yb2mnsb2到Yb9Mn4+ xsb9的结构转变。通过在Mn位上掺杂Ag，可以明显改善A2MnSb2（A = Ca, Yb）的热稳定性，并在此基础上对其晶体结构和热电性能进行了系统的研究。由于具有复杂的阴离子结构，这些相的导热系数极低，即含镱材料Yb2(Mn0.9Ag0.2) sb2在673 K时具有玻璃样导热系数，最小值为0.42 W·m-1·K - 1，同时在673 K时获得了208 μV·K - 1的塞贝克系数。这种A2MnSb2（A = Ca, Yb）相的发现填补了A - mn - sb三元系中关键缺失的成员，这对于理解这些新相的结构和性能至关重要，随着这些研究的进展，基于这种Zintl相的最先进的热电材料的设计是非常有希望的。
Layered structures can facilitate “phonon-glass, electron-crystal (PGEC)” properties, which are crucial for the design of the state-of-the-art thermoelectric materials. In this report, two Mn-containing metastable Zintl phases with layered structures, Ca2MnSb2and Yb2MnSb2, are discovered for the first time. Their structures are isotypic to that of LiZnSb with transition-metal sites partially occupied. Interestingly, these compounds feature very broad homogeneity ranges, which enable flexible tuning on the Mn sites. In addition, close relationships to previously reported Yb9Mn4+xSb9series have been well established by phase exploration, and structure transition from Yb2MnSb2to Yb9Mn4+xSb9was experimentally observed after annealing. The thermal stability of A2MnSb2(A = Ca, Yb) can be significantly improved through Ag doping on the Mn sites, based on which, systematic investigations on the crystal structures and thermoelectric properties were carried out. Benefited from the complex anionic structures, the thermal conductivity of these phases is extremely low, that is, the Yb-containing material Yb2(Mn0.9Ag0.2)Sb2features glasslike thermal conductivity with a minimum value of 0.42 W·m–1·K–1at 673 K, and meanwhile, a high Seebeck coefficient of 208 μV·K–1was obtained at 673 K. The discovery of such A2MnSb2(A = Ca, Yb) phases completed the critical missing members of the A–Mn–Sb ternary family, which is crucial for understanding the structure and properties related to these novel phases, and with the progress of such studies, the design of the state-of-the-art thermoelectric materials based on such Zintl phases is very promising.