Role of added fluorine to enhance the electromagnetic properties of superconducting Y-Ba-Cu-O compounds

Abstract

An experimental study was carried out on the role of a small quantity of fluorine which leads to an increment of the critical current density at 77 K of an Y-Ba-Cu-O compound. Such a small quantity of fluorine did not change its crystal structure according to x-ray diffraction analysis. From the comparison of the magnetization curves of both a bulk and a powder sample, we recognized that the added fluorine plays the role of strengthening superconductive connections among the grains. To clarify the growth mechanism of those grains, we also observed the feature of the grown grains in the fluorine-diffused sample which had an interface between Y1Ba2Cu3Oy and Y1Ba2Cu3F4Oy compounds before sintering.