Based on the electronic structure, the physical properties of Ca1−xYbxZn2Sb2 (x = 0, 0.25, 0.5, 0.75, 1) Zintl compounds are studied. The transport properties can be significantly changed by varying the composition x. The materials under study are more metallic with increasing x and behaves like a semiconductor when x decreases. It is found that CaZn2Sb2 exhibits a larger thermopower magnitude (S = 241μV/K at T = 700 K) and the Seebeck coefficient decreases as x increases. The calculated figure of merit factor of YbZn2Sb2 is found to be low, this is explained by the fact that its structure is very compact and its bandgap is small which lead to high electrical and thermal conductivity due to high carrier concentration (n = 1.25 ⋅ 1020 cm−3 at T = 300 K). On other hand a narrow-gap (0.46 eV for CaZn2Sb2), provides a balance between a high Seebeck coefficient and low electronic thermal conductivity, with a slight increase in the carrier concentration when the temperature increases (3.87 ⋅ 1019 cm−3 at 600 K). As a consequence, CaZn2Sb2 compound is predicted to have good performance for thermoelectric applications. The electrical (σ) and the thermal (K) conductivity for CaZn2Sb2 compound in both directions (along x and z-axes) are calculated. It is obtained that (σxx) is 120% of (σzz) at high-temperature, whereas Szz Seebeck coefficient was higher than Sxx especially at T = 300K (Szz = 246μV/K,Sxx = 213 μV/K). The large value of Szz showed that the transport is dominated by zz-axis.

中文翻译：

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Ca1−xYbxZn2Sb2 (x = 0, 0.25, 0.5, 0.75, 1) Zintl 化合物的结构、电子和热电特性研究

根据电子结构，物理性质钙1-X镱X锌2锑2(X = 0, 0.25, 0.5, 0.75, 1) 研究了 Zintl 化合物。通过改变成分可以显着改变传输特性X. 正在研究的材料随着增加而更具金属性X并且表现得像一个半导体，当X减少。发现钙锌2锑2表现出更大的热电势（小号 = 241μV/K在吨 = 700 ķ)塞贝克系数随着X增加。计算的品质因数镱锌2锑2被发现很低，这是因为它的结构非常紧凑，带隙很小，由于高载流子浓度导致高电导率和热导率（n = 1.25 ⋅ 1020 厘米-3在吨 = 300 ķ）。另一方面，窄间隙（0.46 eV钙锌2锑2），在高塞贝克系数和低电子热导率之间提供平衡，当温度升高时载流子浓度略有增加（3.87 ⋅ 1019 厘米-3在 600 K）。作为结果，钙锌2锑2预计该化合物在热电应用中具有良好的性能。电气(σ)和热(ķ)电导率钙锌2锑2双向复合（沿X和z-轴）计算。得到的是(σXX)是 120%(σzz)在高温下，而小号zz塞贝克系数高于小号XX特别是在吨 = 300ķ(小号zz = 246μV/K,小号XX = 213 μV/K). 大的价值小号zz表明运输主要由Z Z-轴。