Improvement of critical current density in Y-Ba-Cu-F-O compounds by addition of platinum

Platinum added Y-Ba-Cu-F-O compounds with nominal composition YBa2Cu3F0.4OxPty {y=0, 0.3, 0.5} were prepared by a partial melt process performed at lower temperature than the conventionalmelt process. Optical micrograph observations showed that Y2BaCuO5(211) particles increase in density and are dispersed finely when increasing the doping of Pt up to 0.3 wt%. For the 0.5 wt% Pt sample, however, the size of the 211 particles became larger than in the samples containing less than 0.3 wt% Pt. The magnetization was measured using a SQUID magnetometer in the temperature range 20-77 K under magnetic fields Be up to 1 T. The magnetization M also increased with increasing quantity of platinum up to 0.3 wt%. The Jc values estimated from the width of the magnetization curves were 9.8 x 107 A/m2 for the 0.3 wt% Pt sample and 5.4 x 107 A/m2 for the undoped sample at 77 K and Be=0.8 T. In addition, the whereabouts of the platinum in the quenched samples was investigated by using electron spectroscopy for chemical analysis (ESCA). (orig.)