Crystal growth and characterization of superconducting lead cuprates

High quality single crystals of Pb2Sr2(R/Ca)Cu3O8 + y (R = Nd, Sm, Gd, Dy, Er, Tm, Yb, Lu and Y), the 2213 phase of the lead cuprate family, have been grown by PbO/NaCl flux and seed crystal methods. The role of NaCl and the pseudobinary phase diagrams of the crystal growth system are investigated. A correlation between crystal quality and superconducting properties of Pb2Sr2(R/Ca)Cu3O8 + y is observed. The 1212 lead cuprate phase has also been prepared in single crystal form by a semi-ceramic method. The oxygen partial pressure seems to be the key to the determination of the product compound in the crystal growth process; the 2213 lead cuprate phase can be prepared under low oxygen partial pressure while the 1212 phase requires an oxidizing atmosphere.