CRYSTAL-GROWTH OF HIGH-T-C SUPERCONDUCTORS PR2-XCEXCUO4+DELTA WITH SUBSTITUTIONS OF NI AND CO FOR CU

We report the crystal growth of the electron-doped high-T-C supercondu cting Pr2-xCexCuO4+delta by a modified CuO self-flux flow method. We f ound that for the crystal growth process at different Ce concentration s the maximum growth temperature is the most important parameter and r eport about optimized crystal growth procedures for the Ce-concentrati on range x=0-0.18. Using this flux growth method only Ni and Co atoms can be substituted for Cu in the Pr2-xCex(Cu(1-y)M(y))O-4+delta crysta ls, the other substitutional elements that we have tested (M = Fe, Zn, Ga, and Sn) do not dissolve in the T' phase. We introduce a new reduc tion treatment for single crystalline samples which ensures a homogene ous and variable oxygen stoichiometry over the whole crystal.