Structural and thermoelectric properties of Cu6Fe4Sn12Se32 single crystal

We present structural and thermoelectric properties of quaternary selenide Cu6Fe4Sn12Se32 single crystal. Single crystal X-ray structural analysis revealed that Cu6Fe4Sn12Se32 has the cubic thiospinel structure. Low-temperature logarithmic electrical resistivity ln ρ exhibits Mott’s T−1/4 dependence, indicating that three-dimensional variable-range hopping (VRH) is the dominant electrical conduction mechanism. Furthermore, Efros’ T−1/2 dependence of ln ρ appears below 30 K. Thermopower S varies as T1/2 at low temperatures, as expected for the VRH conduction, and reaches 150 μV/K at 300 K. Result of Hall measurement indicates that rather low ρ for a VRH conductor and the large S are attributed to high carrier density and large slope of electron density of states, respectively.

► Structural and thermoelectric properties of Cu6Fe4Sn12Se32 single crystal were investigated.
► Cu6Fe4Sn12Se32 has the cubic thiospinel structure.
► Variable-range hopping is a dominant electrical conduction mechanism at low temperatures.
► Thermopower achieves 150 μV/K around room temperature.