Significant improvement of trapped flux in bulk Gd–Ba–Cu–O grains fabricated by a modified top-seeded melt growth process

Abstract

The seeded infiltration and growth of Gd–Ba–Cu–O single grains using a YBa2Cu3Oy pressed pellet as the liquid source has successfully solved the liquid source leakage problem even at Tmax ∼ 1100 °C. As a development of this process, a simple but essential modification to insert a liquid source pellet at the bottom of the pre-form was made to the top-seeded melt growth process. The present method resulted in a significant enhancement of the trapped flux density of the Gd–Ba–Cu–O grains. In the growth kinetics, we interpreted that the enriched liquid source surrounding the growth front leads to a more uniform distribution of Gd2BaCuO5 in the matrix and an enlarged c-orientation growth area, which help suppress the formation of high angle grain boundaries. Furthermore, we demonstrated that the present method is of great advantage in multi-seeded processes.