Evolution of Thermoelectric Properties in the Triple Cation Zintl Phase: Yb 13–x Ca x BaMgSb 11 ( x = 1–6)
Evolution of Thermoelectric Properties in the Triple Cation Zintl Phase: Yb 13–x Ca x BaMgSb 11 ( x = 1–6)
复制标题
三重阳离子 Zintl 相中热电性能的演变：Yb 13−x Ca x BaMgSb 11 ( x = 1−6)
DOI：
10.1021/acs.chemmater.1c02584
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发表时间：
2021
影响因子：
8.6
通讯作者：
Kauzlarich, Susan M.
中科院分区：
文献类型：
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作者：
Perez, Christopher J.;Cerretti, Giacomo;Wille, Elizabeth L.;Devlin, Kasey P.;Grewal, Navtej S.;Justl, Andrew P.;Wood, Maxwell;Bux, Sabah K.;Kauzlarich, Susan M.
yb14mgsb11的能带结构是通过在四个晶体学上不同的Yb位点（Yb13-xCaxBaMgSb11 (x= 1,2,3,4,5,6)）上取代地球上更丰富的阳离子Ca和Ba来调整的。在锡熔剂中生长出Yb9.7(2)Ca3.85(5)Ba0.29(4)Mg1.13(3)Sb11.0(1)组成的单晶。对该晶体的磁测量显示出与~ 0.85 Yb3+的存在一致的顺磁性行为。采用球磨法和火花等离子烧结法制备了成分接近Yb13-xCaxBaMgSb11 （x= 1-6）的高纯度样品（>98%）。对于所有样品，随着Yb3+的存在，载流子浓度可以合理化，并且在室温下作为xin的函数以系统的方式降低，并且在x= 3-6时，在~ 600 K以上增加。载流子浓度的温度依赖性可以理解，考虑到电子结构的轻带和重带价带对性能的贡献，并表明局域化的平带或杂质态的参与随着Ca的增加而活跃。温度的影响导致持续的高塞贝克系数和低电阻率，这是由于载流子的局域化从轻带过渡到重带富钙成分的平坦带或杂质态。声速测量表明，晶格随着x的增大而变硬。尽管晶格变硬，但导热系数一直减小，直到x= 3,4，此时导热系数略有增加。该x= 4样品在1273 K时达到了1.32的峰值品质值（zT），而与yb14mnsb11相比，其摩尔质量轻了16%，从而提供了更高的功率密度材料。
The band structure of Yb14MgSb11is tuned by substituting the more earth-abundant cations, Ca and Ba, on the four crystallographically distinct Yb sites (Yb13–xCaxBaMgSb11(x= 1, 2, 3, 4, 5, 6)). Single crystals of composition Yb9.7(2)Ca3.85(5)Ba0.29(4)Mg1.13(3)Sb11.0(1)were grown from Sn flux revealing the cation site preferences. Magnetic measurements on this crystal show paramagnetic behavior consistent with the presence of ∼0.85 Yb3+. High-purity samples (>98%) with compositions close to nominal of Yb13–xCaxBaMgSb11(x= 1–6) were prepared by ball milling and spark plasma sintering. The carrier concentration can be rationalized with the presence of Yb3+for all samples and decreases as a function ofxin a systematic fashion at room temperature and increases above ∼600 K forx= 3–6. The temperature dependence of the carrier concentration can be understood considering the electronic structure with a light and heavy band valence band contributing to the properties and suggests the involvement of a localized flat band or impurity state that is active with increasing amounts of Ca. The effect of temperature leads to sustained high Seebeck coefficients with low electrical resistivity arising from the transitioning of the light to heavy band with localization of carriers in the flat band or impurity state for Ca-rich compositions. Speed of sound measurements show that the lattice stiffens with increasingx. Despite the stiffening lattice, the thermal conductivity decreases untilx= 3, 4 at which point it increases slightly. Thex= 4 sample reaches a peak figure of merit (zT) of 1.32 at 1273 K while being 16% lighter by the molar mass compared to Yb14MnSb11thereby providing a more power dense material.