${\mathrm{Yb}}_{14}\mathrm{Mn}{\mathrm{Sb}}_{11}$ is a magnetic Zintl compound as well as being one of the best high temperature $p$-type thermoelectric materials. According to the Zintl formalism, which defines intermetallic phases where cations and anions are valence satisfied, this structure type is nominally made up of 14 ${\mathrm{Yb}}^{2+}$, 1 ${\mathrm{MnSb}}_4^{9-}$, 1 ${\mathrm{Sb}}_3^{7-}$, and 4 ${\mathrm{Sb}}^{3-}$ atoms. When Mn is replaced by Mg or Zn, the Zintl defined motifs become 13 ${\mathrm{Yb}}^{2+}$, 1 ${\mathrm{Yb}}^{3+}$, 1 (Mg, Zn)${\mathrm{Sb}}_4^{10-}$, 1 ${\mathrm{Sb}}_3^{7-}$, and 4 ${\mathrm{Sb}}^{3-}$. The predicted existence of ${\mathrm{Yb}}^{3+}$ based on simple electron counting rules of the Zintl formalism calls the Yb valence of these compounds into question. X-ray absorption near-edge structure, magnetic susceptibility, and specific heat measurements on single crystals of the three analogs show signatures of intermediate valence Yb behavior and in particular, reveal the heavy fermion nature of ${\mathrm{Yb}}_{14}{\mathrm{MgSb}}_{11}$. In these isostructural compounds, Yb can exhibit a variety of electronic configurations from intermediate ($M=\mathrm{Zn}$), mostly 2+ ($M=\mathrm{Mn}$), to 3+ ($M=\mathrm{Mg}$). In all cases, there is a small amount of intermediate valency at the lowest temperatures. The amount of intermediate valency is constant for $M=\mathrm{Mn}$, Mg and temperature dependent for $M=\mathrm{Zn}$. The evolution of the Yb valence correlated to the transport properties of these phases is highlighted. The presence of Yb in this structure type allows for fine tuning of the carrier concentration and thereby the possibility of optimized thermoelectric properties along with unique magnetic phenomena.

中文翻译：

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Zintl相的中间Yb价Yb14MSb11（M = Zn，Mn，Mg）：XANES，磁性和热容

$b_{14}锰{锑}_{11}$ 是一种磁性Zintl化合物，也是最好的高温之一 $p$型热电材料。根据Zintl形式主义，该形式定义了满足阳离子和阴离子化合价的金属间相，该结构类型名义上由14个组成$b^{2+}$，1 ${\mathrm{锰锑}}_4^{9-}$，1 ${锑}_3^{7-}$和4 ${锑}^{3-}$原子。当Mn被Mg或Zn取代时，Zintl定义的基序变为13$b^{2+}$，1 $b^{3+}$，1（镁，锌）${锑}_4^{10-}$，1 ${锑}_3^{7-}$和4 ${锑}^{3-}$。预测的存在$b^{3+}$基于Zintl形式主义的简单电子计数规则，这些化合物的Yb价受到质疑。在三个类似物的单晶上的X射线吸收近边缘结构，磁化率和比热测量结果显示了中间价Yb行为的特征，特别是揭示了重金属的费米子性质。$b_{14}{\mathrm{镁锑}}_{11}$。在这些同构化合物中，Yb可以从中间体（$\mathrm{中号}=锌$），大部分为2+（$\mathrm{中号}=锰$），到3+（$\mathrm{中号}=镁$）。在所有情况下，最低温度下都有少量中间价。中间价的量对于$\mathrm{中号}=锰$，镁和温度取决于 $\mathrm{中号}=锌$。突出了与这些相的输运性质相关的Yb价的演变。在这种结构类型中，Yb的存在允许对载流子浓度进行微调，从而可以优化热电性能以及独特的磁现象。