Growth and characterization of superconducting single crystals of layered 1212 PbSrYCaCu oxide

High quality single crystals of Pb1−ySr2Y1−xCaxCu2+yOz have been grown by spontaneous nucleation from a self-flux and by a semiceramic method from partially molten material. Crystals up to 2×2×1 mm3 have tetragonal symmetry with 3.819 < a < 3.826 Å and 11.823 < c < 11.851 Å. Some of the crystals are partially superconducting “as grown”, others become superconducting after annealing in oxygen with Tonsetc = 40–65 K. These differences are probably caused by inhomogeneous distribution of oxygen and/or calcium in the crystal lattice. The crystals have been characterized by EDAX, EPMA and Guinier powder X-ray diffraction and their uniformity, as well as the influence of annealing on their superconducting properties are discussed.