Abstract
Microstructures of high-Jc YBaCuO material fabricated by Melt-Powder-Melt-Growth process were studied by transmission electron microscopy to clear the most effective pinning center in the material. It turns out that the interface between the YBa2Cu3O7 matrix and Y2BaCuO5 inclusion is sharp. Such an interface may act as a strong pinning center, and the large Jc value of the MPMG processed material is thought to be brought by the 211 inclusions with sharp interfaces.