CONTROL OF Y2BACUO5 MORPHOLOGY IN MELT-TEXTURED Y-BA-CU-O OXIDES WITH PTO2-CENTER-DOT-H2O ADDITION

The influence of precursor composition (YBa2Cu3Ox and Y1.6Ba2.3Cu3.3Ox) and a procedure of PtO2 . H2O addition on Y2BaCuO5 morphology was investigated in melt-textured Y-Ba-Cu-O oxides. It is found that the 2-1-1 morphology sensitively depends not only on the composition of the starting material but also on the adding procedure of PtO2 . H2O powder. In YBa2Cu3Ox, coarse/plate-like Y2BaCuO5 particles are produced, while fine/equiaxed 2-1-1 particles are produced in Y1.6Ba2.3Cu3.3Ox. On the other hand, needle-like 2-1-1 particles are produced when 1 wt.% PtO2 . H2O was added to Y2O3-BaCO3-CuO while granular 2-1-1 particles are produced when PtO2 . H2O was added to YBa2Cu3Ox-Y2BaCuO5 powder. Y2BaCuO5 morphologies developed from precursors with/without PtO2 . H2O addition are discussed on the basis of the growth behavior of Y2BaCuO5 particles at the reaction stages (the solid-state, incongruent melting and peritectic reaction) of melt-texture processing.