Balthes, EduardBreining, AngelaKahlich, SiegfriedMoldenhauer, JörgSchweitzer, DieterBele, PetraBrunner, HermannHeinen, IlsabeNuber, BernhardKeller, Heimo J.2011-08-162016-03-312011-08-162016-03-31199335417603Xhttp://nbn-resolving.de/urn:nbn:de:bsz:93-opus-65736http://elib.uni-stuttgart.de/handle/11682/5064http://dx.doi.org/10.18419/opus-5047Investigations of the transport properties of single crystals and polycrystalline pressed samples of K-( BEDT-TTF)2I3 are presented. In contrast to polycrystalline pressed samples of K-(BEDT-TTF)2Cu(NCS)2 and K-(BEDT-TTF)2Cu [N(CN)2]Br those of K-(BEDT-TTF)2I3 show bulk superconductivity indicating that the loss of superconductivity in the first two types of samples is not due to the special structure of the K-phase, but probably due to a disproportionation of Cu1+ under the anisotropic pressure during the preparation of the samples. Annealing the single crystals as well as the polycrystalline pressed samples of K-(BEDT-TTF)2I3 at 75°C for a few days results in a structural transfomation with an increase in the transition temperature for superconductivity (about 8 K for the crystals). IR-spectra indicate a transfomatlon into a structure which is identical with αt-(BED-TTF)2I3 which seems to be the thermodynamically most stable phase of the several (BEDT-TTF)2I3 phases.eninfo:eu-repo/semantics/openAccessTetrathiafulvalen , Organischer Supraleiter530article2011-08-16