YBCO films were prepared by pulsed laser deposition from nanocrystalline targets doped with different concentrations of BaZrO 3 ranging from c = 0.9 to 9.0 wt%. The critical temperature of the films decreases almost linearly with increasing BaZrO 3 content whereas the critical current density shows a maximum near 3.9 wt%. In comparison with undoped YBCO films the accommodation field B * is considerably enhanced and the critical current density is improved in high fields in the films doped with BaZrO 3 , e.g. for c = 3.9 wt% by factor of 4.5 in a field of 5 T at 5 K. In the doped films the BaZrO 3 particles grow epiaxially with YBCO. Transmission electron microscopy results show that the density of the BaZrO 3 particles increases with increasing doping but the particle size remains practically the same (5-10 nm).
The plume generated by a pulsed XeCl laser from a novel nanostructured YBaCuO target (n target) is investigated by methods of optical emission spectroscopy and atomic force microscopy. While the spectral positions of the emission lines are the same, stronger line intensities, pertinent to higher kinetic energy of the particles, are observed in the plumes generated from the n target than from a target having micron size grains (m target). The size of small clusters captured on Si plates assembled inside the plume grows in directions perpendicular to the axis of the plume. As shown by x-ray photoelectron spectroscopy investigations, in the particles deposited on a SrTiO3 substrate at Ts=700 °C in oxygen the correct 1-2-3 composition is achieved. The average ratio of the heights of the particles deposited from the n target and from the m target is hn/hm=0.6, both in the plume and on SrTiO3. This can explain the smoothness of YBaCuO films prepared by laser deposition from the n targets.
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