Influence of crystal growth regimes on the structure and properties of Cu-intercalated Ta1+yS2

Ta1+yS2 and Cu-intercalated Ta1+yS2 crystals with high Cu concentration were grown by the chemical vapour transport method with different crystal growth regimes. Depending on the cooling process either 2H-type or 6R-type CuxTa1+yS2 crystals were grown. Transformation of 2H-CuxTa1+yS2 polytype crystals to 6R-CuxTa1+yS2 takes place during a low cooling process, whereas during air quenching 2H-type crystals result. It was shown that cooling process and additional annealing steps in crystal growth regimes have an essential influence on the structure of the samples and their physical properties such as superconductivity. The samples were examined by X-ray diffraction, energy dispersive X-ray spectroscopy and electrical resistivity measurements.