Growth of the superconducting phase in ceramic Y sub(1.2)Ba sub(0.8)CuO sub(y) samples

Differently prepared samples with the nominal composition Y sub(1.2)Ba sub(.0.8)CuO sub(y) are examined via microscopy, energy dispersive x-ray analysis, x-ray diffraction, and measurements of resistivity and susceptibility. Various phases are identified directly. Essentially these are Y sub(2)BaCuO sub(5), which forms a matrix with semiconducting and antiferromagnetic properties and YBa sub(2)Cu sub(3)O sub(7-x), which is present in a dendritic morphology. The dendritic appearance indicates that YBa sub(2)Cu sub(3)O sub(7-x) is formed by nucleation and growth during sintering.