Microstructure and superconductivity of YBCO by the melt-spun-texture-growth method

The Y-Ba-Cu-O (YBCO) superconducting material prepared by the melt-spun-texture-growth method has been examined with transmission electron microscopy (TEM). Its volume density nearly approaches the theoretical value and the grain boundaries are clear and narrow. TEM images revealed that there exists a competitive relationship between dislocations and {110} twins in the superconducting phase, and that there are few dislocations but a lot of twins around the Y2BaCuO5 phase. It is also detected that the critical current density J(c) is lower when the YBCO material has a lower oxygen content, but J(c) could be increased tremendously by prolonging the time of diffusing oxygen into grains.