Thermoelectric transport properties of CuFeInTe3

• Polycrystalline CuFeInTe3 alloys were successfully synthesized using the melt and anneal technique.
• Thermolectric behavior was investigated from room temperature to 450 K.
• Both crystal structure as well as electronic structure are altered by the inclusion of Fe2+ ions.
• The zT value of CuFeInTe2 reaches 0.126 at 450 K.

In this paper we report on the preparation of CuFeInTe3 and its thermoelectric properties. Optical diffuse reflectance and Raman scattering spectroscopies, as well as X-ray powder diffraction were also carried out. Unprecedented for CuFeInTe3, a direct and an indirect band gap were found from its absorption spectrum. From Hall effect measurements at 300 K the carrier concentration (n), electrical conductivity (σ) and mobility (μ) were determined. In order to investigate whether this material is suitable for thermoelectric applications, the Seebeck coefficient (S), the thermal conductivity (κ) and σ as a function of temperature were measured. The measurements of Hall and Seebeck coefficients showed that alloying CuInTe2 with Fe2+ produces a change from the original p-type to n-type conductivity and causes a decrease in the κ value, while leaving σ unchanged. Relatively large S values were found for CuFeInTe3, with respect to CuInTe2, which were explained on the basis of a probable electron effective mass increase due to Fe2+ incorporation. It was also found, that thermal and electrical conductivities decrease with increasing temperature in the range between 300 and 450 K, while the figure of merit (zT) reaches values of 0.075 and 0.126 at 300 and 450 K respectively. Thus, the zT of CuFeInTe3 increases with temperature, reaching values larger than those reported for CuInTe2.

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