CuInTe₂ and CuAlTe₂, which are ternary chalcogenide compounds with the same tetragonal structure, are considered as thermoelectric materials owing to high Seebeck coefficients with large bandgaps of ∼1.08 and 1.96 eV, respectively. In this study, the electrical, thermal, and thermoelectric properties of a CuInTe₂–CuAlTe₂ solid solution alloy system were systematically investigated by synthesizing a series of CuIn_1−xAl_xTe₂ (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) compositions. CuInTe₂ and CuAlTe₂ form the complete solid solutions as reported, and the electrical conductivity and Seebeck coefficient decrease simultaneously to x = 0.8 due to a significant reduction in carrier mobility, thereby reducing the power factor. For CuAlTe₂, the power factor suddenly increased owing to its very high electrical conductivity. On the other hand, the total and lattice thermal conductivity is greatly reduced by additional phonon scattering originating from solid-solution alloying. For instance, the largely reduced lattice thermal conductivity was measured to be 1.8 and 1.9 W m⁻¹ K⁻¹ for the sample with x = 0.4 and x = 0.6 at 300 K, whereas those for CuInTe₂ and CuAlTe₂ were 4.8 and 5.6 W m⁻¹ K⁻¹, respectively. Nevertheless, the thermoelectric figure of merit zT was significantly reduced by the solid solution alloying due to a significant reduction of power factors despite the reduction in thermal conductivity.

中文翻译：

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在 CuInTe2-CuAlTe2 固溶体合金中观察到晶格热导率显著降低


CuInTe₂ 和 CuAlTe₂ 是具有相同四方结构的三元硫系化合物，由于塞贝克系数高，带隙分别为 ∼1.08 和 1.96 eV，因此被认为是热电材料。在本研究中，通过合成一系列 CuIn_1−xAl_xTe₂ （x = 0、0.2、0.4、0.6、0.8 和 1.0） 成分，系统研究了 CuInTe 2-CuAlTe ₂ 固溶体合金系统的电、热和热电性能。CuInTe₂ 和 CuAlTe₂ 构成了报道的完整固溶体，由于载流子迁移率显著降低，电导率和 Seebeck 系数同时降低到 x = 0.8，从而降低了功率因数。对于 CuAlTe₂，由于其非常高的导电性，功率因数突然增加。另一方面，固溶体合金化产生的额外声子散射大大降低了总热导率和晶格热导率。例如，在 300 K 时，对于 x = 0.4 和 x = 0.6 的样品，测得大幅降低的晶格热导率为 1.8 和 1.9 W ^{m-1 K-1}，而 CuInTe₂ 和 CuAlTe₂ 的晶格热导率分别为 4.8 和 5.6 W ^{m-1 K-1}。 然而，尽管热导率降低，但由于功率因数显著降低，固溶体合金化导致热电品质因数 zT 显著降低。