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In this paper we report on the preparation of CuFeInTe 3 and its thermoelectric properties. Optical diffuse reflectance and Raman scattering spectroscopies, as well as X-ray powder diffraction were also carried out. Unprecedented for CuFeInTe 3 , a direct and an indirect bang 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 CuInTe 2 with Fe 2+ produces a change from the original p-type to n-type conductivity and causes a decrease in κ value, while leaving σ unchanged. Relatively large S values were found for CuFeInTe 3 , with respect to CuInTe 2 , which were explained on the basis of a probable electron effective mass increase due to Fe 2+ 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, zT of CuFeInTe 3 increases with temperature, reaching values larger than those reported for CuInTe 2 .

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The temperature dependencies of DC magnetic susceptibilities, x(T), of CuFeInTe 3 and CuFeGaTe 3 alloys were measured in a SQUID apparatus using the protocol of field cooling (FC) and zero FC (ZFC). The FC curves of both samples reflect a weak ferromagnetic (or ferrimagnetic) behavior with a nearly constant value of x(T) in the measured temperature range (2-300 K) indicating that the critical temperatures (T c ) are >300 K. The ZFC curves diverges from FC, showing irreversibility temperatures (T irr ) of $250 K for CuFeInTe 3 and >300 K for CuFeGaTe 3 , suggesting that we are dealing with cluster-glass systems in a superparamagnetic state.

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