Thermoelectric performance of Cu1−x−δAgxInTe2 diamond-like materials with a pseudocubic crystal structure

Abstract

Multiple degenerate band engineering has been established as an effective approach to maximize electrical transport in thermoelectric materials. A series of polycrystalline samples of chalcopyrite Cu_1−x−δAg_xInTe₂ (x = 0–0.5, δ = 0.02–0.05) was synthesized, to achieve multiple degenerate bands. A pseudocubic structure is realized when x is around 0.2. As a result, the degenerate valence bands influence electrical transport significantly. In addition, the lattice thermal conductivity is significantly depressed in the solid solution due to the strong phonon scattering by strain-field fluctuations, since Ag substitution brings significant anharmonicity to the crystal structure. The highest ZT of 1.24 was obtained at the composition Cu_0.75Ag_0.2InTe₂. This study provides an example how the pseudocubic crystal structure is applied to design and evaluate the TE properties in diamond-like compounds.

Scientific collaboration between the Shanghai Institute of Ceramics and the Institutes of the Max-Planck Society has a long history. In 2001, the Max-Planck Institute for Chemical Physics of Solids in Dresden and SIC CAS in Shanghai established research cooperation. At the beginning it was focused on the field of solid state chemistry, and later was extended to the studies on thermoelectric materials. Currently this cooperation is intensively realized by the research groups of Prof. Lidong Chen in Shanghai and Prof. Yuri Grin in Dresden. Several publications in journals like Inorganic Chemistry, Dalton Transactions and Chemistry of Materials, as well as numerous presentations in the national and international conferences present the results of the common studies.