Observation of n-type behavior in Fe-doped tetrahedrite at low temperature
Weller, D.P.; Kunkel, G.E.; Ochs, A.M.; Morelli, D.T; Anderson, M.E. Observation of n-type behavior in Fe-doped tetrahedrite at low temperature. Materials Today Physics.2018, 7.1, 1-6.
Tetrahedrite exhibits favorable thermoelectric properties, while also being composed of non-toxic and earth-abundant elements. Although tetrahedrite has been studied extensively as a p-type thermoelectric, n-type behavior in this material has not yet been observed. We report the first findings of n-type conductivity in tetrahedrite observed over a temperature range of 80 to 310 K, with typical p-type conductivity found at higher temperatures. Herein, we characterize electrical and thermal transport properties on these samples from 80 to 673 K. Mechanical alloying and modified polyol synthesis methods were used to synthesize Fe-doped samples (Cu12-xFexSb4S13 with x = 1, 1.3, and 1.5) by solid-state and solution-phase approaches, respectively. Elemental analysis by energy-dispersive X-ray spectroscopy was conducted to investigate the relationship between thermoelectric properties and chemical composition. A maximum ZT = 0.67 at 673 K was obtained for Cu10.5Fe1.5Sb4S13 synthesized by the modified polyol process. Our observation of negative Seebeck coefficient values in the low-temperature regime should serve as a foundation for further study of n-type behavior in tetrahedrite materials.
Materials Today Physics