Constantina Andreouli

UV laser beam/YBCO target interaction for optimum preablation for the growth of YBCO thin films

The morphological and compositional changes which take place during the laser irradiation of YBCO targets are discussed. The understanding of the evolution of target composition, will lead to better control of film quality. In the case stated here, a XeCl excimer laser was used to irradiate rotated and also non-rotated YBa2Cu3O7-x targets. The modified surface of these targets was systematically studied by scanning electron microscopy and energy dispersive x-ray microanalysis. It was observed that some crucial deposition parameters, such as the number of pulses and fluence has a strong effect on the roughening of the target. A comparative study was done on the derived High-Tc superconducting thin films. It was shown that the conditions during the preablation procedure which affect the target surface morphology correlate closely with the appearance of laser droplets on the film surface.

Processing effect on microstructure and superconducting properties of sintered ReBa2Cu3Oy ceramics — the role of ionic radius

Abstract A comparison study of the processing parameters for the production of single phase sintered ReBa 2 Cu 3 O y samples (Re=Nd, Eu, Gd, Dy, Ho, Er), with good superconducting properties was carried out. The relationships between the microstructure of sintered ReBa 2 Cu 3 O y superconductors and processing variables (sintering time, sintering temperature) were examined. It was found that the superconducting properties and microstructural parameters such as density, mean grain size and the presence of secondary phases are strongly dependent upon the processing conditions and the Re-ion size of the ReBa 2 Cu 3 O y systems.