Structure–property relationships along the Fe-substituted CuInS2 series: Tuning of thermoelectric and magnetic properties

• Published in: Materials chemistry and physics Vol. 147; no. 1-2; pp. 17 - 27
• Main Authors: Burnett, Johanna D., Gourdon, Olivier, Ranmohotti, Kulugammana G.S., Takas, Nathan J., Djieutedjeu, Honore, Poudeu, Pierre F.P., Aitken, Jennifer A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2014
• Subjects: Inorganic compounds; Magnetic materials; Neutron diffraction; Powder diffraction; Thermal conductivity; Thermoelectric effects; Thermal conductivity; Magnetic materials; Powder diffraction; Inorganic compounds; Thermoelectric effects; Neutron diffraction
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2014.03.034

CuIn1−xFexS2 (x = 0–0.15) was synthesized via high-temperature, solid-state synthesis. Rietveld refinements using the neutron and synchrotron powder diffraction data indicate that all Fe-substituted materials are phase pure with the exception of the CuIn0.85Fe0.15S2 sample, which contains a minute secondary phase. These refinements also verify that iron resides on the indium site in the CuIn1−xFexS2 materials. CuIn0.875Fe0.125S2 displayed the lowest total thermal conductivity of the series, 1.37 W m−1 K−1 at 570 K, as well as the highest thermopower, −172 μV K−1 at 560 K. The electrical conductivity increases over six times upon going from CuInS2 to CuIn0.875Fe0.125S2. These improved properties result in an increase in the thermoelectric figure of merit (ZT) of CuInS2 by over an order of magnitude for the x = 0.125 sample. Magnetic measurements reveal the x = 0–0.10 samples to be paramagnetic, while the sample in which x = 0.125 displays ferromagnetic ordering below 95 K. [Display omitted] •Up to 12.5% of the In3+ is replaced with Fe3+ in CuInS2.•Rietveld refinements using powder diffraction data show iron on the indium site.•CuIn0.875Fe0.125S2 is ferromagnetic below 95 K.•The thermal conductivity of CuIn0.875Fe0.125S2 is 1.37 W m−1 K−1 at 570 K.•The ZT of CuInS2 increased by over an order of magnitude with iron substitution.