Mechanochemistry for Energy Materials: Impact of High‐Energy Milling on Chemical, Electric and Thermal Transport Properties of Chalcopyrite CuFeS(2) Nanoparticles

Chalcopyrite CuFeS(2), a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste‐free and inexpensive. The synthesized nano‐powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS(2) powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano‐powders are corroborated by the universal evolution of the parameter S(BET)/X (S(BET) ‐specific surface area, X‐crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non‐doped semiconducting CuFeS(2) enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.