Microstructure of YBCO bulk superconductors with CeO2 addition

The refinement of Y2BaCuO5 (Y211) particles by CeO2 in the single-grain YBa2Cu3O7/Y2BaCuO5 (Y123/Y211) bulk superconductors of nominal composition Y1.5Ba2Cu3Ox prepared by top-seeded melt-growth process with Y2O3 addition has been studied by polarised light microscopy. It is shown that cerium is active in the Y211 particle refinement when it is solved in the peritectic melt, Lp. Observed growth of Y211 particles during sintering stage is ascribed to higher amount of melt induced by CeO2 reaction with Y123 phase producing barium cerate and CuO.