TOP-SEEDED SOLUTION GROWTH OF YBA2CU3O6+D SUPERCONDUCTIVE CRYSTALS

YBa2Cu3O6+d superconductive crystals are formed by top-seeded solution growth under a temperature gradient in which the nutrient is a Y2BaCu O5 phase on the bottom and the solvent is molten barium cuprate with t he cation ratio of Ba:Cu = 3:5. The crystal misorientation (< 0.2 degr ees) was determined by neutron diffraction. The superconducting transi tion temperature was about 90 K after appropriate oxygenation. Praseod ymium-substituted crystals, (PrxY1+/-x)Ba2Cu3O6+d, were also grown by adding PrBaO3 + BaCuO2 . 2CuO into the solution. We observed different types of growth steps on crystallographically different surfaces. The growth steps on the (001) face were formed by one lattice constant of c-axis height, while those on the (100) face were composed of macrost eps 60 nm high and microsteps about 1 nm high.