H. Dwelk
Humboldt University of Berlin
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Publication
Featured researches published by H. Dwelk.
Superconductor Science and Technology | 1991
A. Krapf; G Lacayo; G Kastner; W. Kraak; N. Pruss; H Thiele; H. Dwelk; R. Herrmann
Fibrous single crystals of Bi-Sr-Ca-Cu-O have been grown from the melt of the corresponding oxides and carbonates. The crystals are mostly flat ribbon-like whiskers with the long edge in the a direction and the c axis perpendicular to the face. There exists a superstructure in the b direction. Dislocations observed are mainly parallel in the a axis. The whiskers are elastic and they can be bent with a radius of curvature of down to 0.02 mm. The whiskers show a single-phase behaviour in the temperature dependence of the electrical resistivity with a critical temperature Tcm=81.5 K.
Physica C-superconductivity and Its Applications | 1988
R. Herrmann; N. Kubicki; H.-U. Müller; H. Dwelk; N. Pruss; A. Krapf; L. Rothkirch
In order to study the influence of fluorine on the superconductivity of YBa 2 Cu 3 O 7−y we have prepared samples of YBa 2 Cu 3 O 7−y with x = 0 – 2.5. For all samples the onset temperature is 91 K. The zero lesistence temperature To for samples with large x values decreases strongly and the lattice parameter c increases for about 0.5 %.
Physica Status Solidi B-basic Solid State Physics | 1988
R. Herrmann; N. Kubicki; H.-U. Müller; H. Dwelk; N. Pruss; A. Krapf; L. Rothkirch
Physica Status Solidi B-basic Solid State Physics | 1974
U. Preppernau; R. Herrmann; L. Rothkirch; H. Dwelk
Physica Status Solidi (a) | 1990
W. Kraak; A. Krapf; G. Nachtwei; M.-U. Müller; H. Schötz; H. Dwelk; R. Herrmann; P. Vasek; P. Svoboda
Physica Status Solidi B-basic Solid State Physics | 1987
R. Herrmann; N. Kubicki; Th. Schurig; H. Dwelk; U. Preppernau; A. Krapf; H. Krüger; H.-U. Müller; L. Rothkirch; W. Kraak; W. Braune; N. Pruss; G. Nachtwei; F. Ludwig; E. Kemnitz
Physica Status Solidi B-basic Solid State Physics | 1978
L. Rothkirch; R. Herrmann; H. Dwelk; U. Preppernau
Physica Status Solidi B-basic Solid State Physics | 1989
N. Pruss; W. Kraak; N. Kubicki; H. Dwelk; R. Herrmann
Physica Status Solidi B-basic Solid State Physics | 1989
R. Herrmann; U. Preppernau; Ch. Rellin; A. Krapf; H. Dwelk
Physica Status Solidi (a) | 1989
N. Pruss; W. Kraak; H.-U. Müller; A. Jacobi; H. Dwelk; R. Herrmann
