The influence of process parameters on the growth morphology of large-grain Pt-doped YBCO fabricated by seeded peritectic solidification

We report an investigation of the processing of large-grain Y-Ba-Cu-O (YBCO) containing 0.1, 0.2 and 0.5 wt% platinum (Pt) doping using seeded peritectic solidification in a vertical tube furnace. In this study differential thermal analysis of the Pt-doped YBCO powders and careful temperature calibration of the furnace were performed in order to determine optimum values of the thermal process parameters for each composition. The seeded melt process was observed to be extremely sensitive to the melting temperature, peritectic solidification temperature and cooling rate during grain growth, and failure to optimize these parameters can result in various undesirable effects such as incomplete melting, the nucleation of multiple grains and the formation of local regions of impurity concentration within the sample. Scanning electron microscopy and vibrating sample magnetometry were employed to investigate the microstructure and current-carrying capabilities of the samples. From these, 0.1 wt% Pt doping was determined to be sufficient for the fabrication of melt-processed samples containing fine, sub-micron-sized Y-211 particles which exhibited high critical current densities. No improvement in sample properties was observed for higher levels of Pt doping. (author)