CRYSTAL-GROWTH OF BI-BASED (85-K) HIGH-TC SUPERCONDUCTING COMPOUNDS WITH A MIRROR FURNACE

We have performed crystal growth experiments by travelling solvent floating zone method (TSFZ) on the high-T(c) superconducting 2212 Bi phase. Hi substitutions were performed and the influence on the crystal growth process and physical properties of the crystals were studied. Homogeneous single crystals with compositions Bi2.18Sr1.87Ca0.99Cu1.97O8+x, Bi2.17Sr1.91Ca0.93Cu1.97Ni0.019O8+x and Bi2.16Sr1.97Ca0.85Cu1.98Ni0.036O8+x were grown from a solvent of nominal composition Bi2.6Sr1.9CaCu2.6O(x) using sintered feed starting material of nominal composition Bi2.1Sr1.9CaCu2-yNi(y)O(x) with y = 0, 0.02 and 0.04 respectively. The size of the cleaved Bi2.18Sr1.97Ca0.99Cu1.97O8+x single crystals are up to 15 x 4 x 0.12 mm3; however, Ni doped single crystals are smaller with increasing Ni content. The superconducting transition temperature T(c) measured by AC magnetic susceptibility in a magnetic field of 0.5 G and 90 Hz is 88.3 K (DELTA-T(c) = 2.2 K) for pure 2212, while for Ni-doped single crystal the superconducting transition is suppressed to T(c) = 83.1 K (y = 0.02) and T(c) = 77.8 K (y = 0.04). Powder X-ray and Laue X-ray measurements were performed in order to measure the lattice parameters and to check the quality of the crystals. It was recognized that Ni doping negatively influences the crystal growth behaviour.