M. Krupska

Hydrogen storage in Ti, V and their oxides-based thin films*

We have investigated the hydrogen storage ability and the effect of hydrogenation on structure and physical properties of Ti/V and their oxides-based thin films. A series of Ti–TiO2 and VOx–TiO2 thin films with different layer structures, geometries and thicknesses have been prepared by the sputtering technique on different (Si(111), SiO2, C) substrates. For the Ti–TiO2–Ti films up to 50 at.% of hydrogen can be stored in the Ti layers, while the hydrogen can penetrate without accumulation through the TiO2 layer. A large hydrogen storage was also found in some V2O5–TiO2 films. Hydrogen could also remove the preferential orientation in the Ti films and induce a transition of V2O5 to VO2 in the films.

Superconductivity in the splat-cooled UMo alloys

We have investigated the superconductivity in splat-cooled UMo alloys by low-temperature resistivity and specific-heat measurements down to 0.4 K. The γ-U materials, such as U-Mo15 (with 15 at.% Mo doping), exhibit a conventional BCS superconductivity with Tc = 2.1 K and upper critical field exceeding 5 T, much higher than that for α-U materials. The alloys with <10 at.% Mo doping consist of a mixed γ + α-U phase. The superconducting transition in the U-Mo6 revealed by a smooth decrease below 1.5 K and a sharp drop at 0.6 K in the resistivity indicating that γ-U grains are embedded in the α-U matrix. The superconductivity transition was revealed by λ-type peak at Tc in the C(T) curve only for U-Mo15, while only one broad peak at Tc in the C(T) curves were observed for other UMo splats. With applying the magnetic fields, the resistivity jumps and specific-heat peaks move to lower temperatures.