Y2BaCuO5 Particle Distribution in YBa2Cu3O7-y Grains of Melt Growth Processed YBCO Oxides

Abstract Y 2 BaCuO 5 (Y211) particle distribution within YBa 2 Cu 3 O 7-y (Y123) grains of YBCO samples melt growth (MG) processed was examined. To understand the processing variables on the Y211 distribution, a cooling rate ( R C =1 K/h to R C =20 K/h) through a peritectic temperature ( T p = 1010 °C), a precursor powder size and composition were changed. Two different Y211 distributions (a linear x-like track and planar butterfly-like pattern) were observed, depending on the processing variables. The linear x-like Y211 tracks were observed in the Y123 samples prepared using a stoichiometric Y123 precursor, whereas the planar butterfly-like Y211 patterns were observed in the Y 1.8 Ba 2.4 Cu 3.4 O 7-d (Y1.8) samples prepared using an Y211-excess composition precursor. The track and planar Y211 patterns were clearer at lower R C (slower growth rate of Y123 grains) and for the smaller Y211 particles. In contrast, the random Y211 distribution was dominant at the higher R C and for the larger Y211 particles. The Y211 distribution patterns in the Y123 grains were explained in terms of the interfacial energy difference among growing Y123 fronts.