Y2BaCuO5 particle coarsening during melt processing of YBa2Cu3O7−x
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Quenching experiments were carried out to study the coarsening phenomena of Y2BaCuO5 (211) particles in liquid (Ba3Cu5O8) which form as a result of the peritectic decomposition of YBa2Cu3O7−x (123) above 1010°C. The morphology of 211 particles was observed to become more acicular as the time of hold increased at 1040°C, showing an anisotropic growth rate of the 211 particles in the liquid. Also, the coarsening rate was found to be increased in the presence of excess added liquid phase (Ba3Cu5O8) in the 123. Externally added 211 particles were found to act as heterogeneous nucleation sites for the peritectically formed 211. The observed cored 211 morphology development in the Er 211 doped, melt textured, Y 123 pellets was explained on the basis of ripening of 211 particles. Reduced coarsening of 211 particles was observed in the presence of 0.5 wt.% Pt doping.
Key words123 superconductors coarsening melt processing second phase additions solidification
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