Electrical and thermal transport properties of layered Bi2YO4Cu2Se2

Abstract

Bi2YO4Cu2Se2 possesses a low thermal conductivity and high electrical conductivity at room temperature, which was considered as a potential thermoelectric material. In this work, we have investigated the electrical and thermal transport properties of Bi2YO4Cu2Se2 system in the temperature range from 300K to 873K. We found that the total thermal conductivity decreases from ~1.8Wm−1K−1 to ~0.9Wm−1K−1, and the electrical conductivity decreases from ~850S/cm to ~163S/cm in the measured temperature range. To investigate how potential of Bi2YO4Cu2Se2 system, we prepared the heavily Iodine doped samples to counter-dope intrinsically high carrier concentration and improve the electrical transport properties. Interestingly, the Seebeck coefficient could be enhanced to ~+80μV/K at 873K, meanwhile, we found that a low thermal conductivity of ~0.7Wm−1K−1 could be achieved. The intrinsically low thermal conductivity in this system is related to the low elastic properties, such as Young's modulus of 70–72GPa, and Grüneisen parameters of 1.55–1.71. The low thermal conductivity makes Bi2YO4Cu2Se2 system to be a potential thermoelectric material, the ZT value ~0.06 at 873K was obtained, a higher performance is expected by optimizing electrical transport properties through selecting suitable dopants, modifying band structures or by further reducing thermal conductivity through nanostructuring etc.