Hansen, Anna-LenaAnna-LenaHansenDankwort, TorbenTorbenDankwortGroß, HendrikHendrikGroßEtter, MartinMartinEtterKönig, Jan D.Jan D.KönigDüppel, ViolaViolaDüppelKienle, LorenzLorenzKienleBensch, WolfgangWolfgangBensch2022-08-192022-08-192017https://publica.fraunhofer.de/handle/publica/25120310.1039/c7tc02983gWe report on the structural alterations of the thermoelectric material CuCrS2 introduced by the removal of 1/3 of the Cu+ ions which are located between CrS2 layers. X-ray diffraction (XRD) and pair distribution function (PDF) analyses revealed a newly formed Cu0.66CrS2 phase with monoclinic symmetry and a 3a superstructure. Simultaneously, a distortion of CrS6 octahedra is observed strongly indicating the oxidation of Cr3+ RT Cr4+ leading to a Jahn-Teller distortion. The structural features extracted from XRD indicate a pronounced disorder in the cationic sub-lattice at moderate temperatures (400 K). Transmission electron microscopy (TEM) examination elucidates the formation of a second Cu0.66CrS2 phase without the superstructure, caused by incipient Cu+ mobility upon beam irradiation. The synergetic combination of high temperature XRD and TEM investigations unveiled the complete mechanism of the phase transition occurring at 503 K, where a transformation into the spinel CuCr2S4 and stoichiometric CuCrS2 occurs.enthermoelectric materialtransmission electron microscopy621541journal article