Room-temperature structure of the 90-K bulk superconductor YBa2Cu3O8-x

High Tc Superconductors using Solution Techniques

We have investigated different solution techniques to synthesize the Cu-based superconductors in the thick film form. Thick films of YBa2Cu3O7 have been produced using controlled precipitation techniques. Bi-based and Tl-based materials have been deposited by spraying of ionic solutions. The numerous difficulties encountered during each process are analyzed in order to propose new synthesis procedures such as a new method, based on the precipitation of hydroxides only, which is described as a prospective for lowering the synthesis temperature and shortening the reaction time.

Application of Direct Methods to powder data. A weighting scheme for intensities in the optimal symbolic addition program SIMPEL88

Application of Direct Methods to reflection intensities obtained by powder diffraction is often obstructed by the fact that not all intensities are reliable. In this paper a weighting scheme is proposed to overcome this problem. The scheme is implemented in the Direct Methods program SIMPEL88 in such a way that phase relations containing overlapping reflections are less probable than they would have been containing very reliable reflections only. Preliminary test results show that this way of tackling the problem is very promising.