The study on melting behavior of precursor powders for powder melting processed YBa2Cu3O7−x superconductors

We have investigated the melting behavior of precursor powder for YBa2Cu3O7−x superconducting bulks prepared by powder melting process (PMP). The phase transition and the melting process have been studied by high temperature X-ray powder diffractometer and differential analyzer. The results have shown that the PMP precursor powders including Y2BaCuO5, BaCuO2 and CuO can transform into the YBa2Cu3O7−x phase if the heating rate is not very high, whereas the YBa2Cu3O7−x would not appear when the fast heating rate is used. The microstructure of these samples prepared by different heating rates has been also investigated by scanning electron microscopy. The results are available to understanding the mechanism of powder melting process.