Inhaltszusammenfassung

Niobium films on sapphire were reacted in tin-vapour to Nb~3Sn with resistance ratios R(297K)/R(18.3K) up to 6 and resistively measured superconducting transition temperatures T~ up to 17.93 K. The composition Nbs+~Snl_=Hx of electrolytically hydrogenated samples was determined depth dependent by Rutherford backscattering of 30MeV 32S and simultaneous detection of recoiled protons. Considerable concentration gradients in the thin layers (~ 0.27 gin) were detected. The increase of resisti...Niobium films on sapphire were reacted in tin-vapour to Nb~3Sn with resistance ratios R(297K)/R(18.3K) up to 6 and resistively measured superconducting transition temperatures T~ up to 17.93 K. The composition Nbs+~Snl_=Hx of electrolytically hydrogenated samples was determined depth dependent by Rutherford backscattering of 30MeV 32S and simultaneous detection of recoiled protons. Considerable concentration gradients in the thin layers (~ 0.27 gin) were detected. The increase of resistivity p with hydrogen content and the change in the temperature dependence of p is analyzed. A correlation between T~ and p0=p(18.3K) is found: An increase of AT~=0.2K at po~25gf2cm and x~0.03 is followed by a drastic decrease to T~<I.IK at Po ~ 80 gf~ cm and x~ 1. The T~ vs. Po and T~ vs. p(T) characteristic correlations are different from "universal" irradiation or preparation induced correlations. The discrepancies can be interpreted by a stiffening of phonon modes and a band-shifting caused by the hydrogen.» weiterlesen» einklappen

Autoren

Klassifikation

DFG Fachgebiet:
Physik der kondensierten Materie

DDC Sachgruppe:
Physik