HOMOGENEITY OF BI2SR2CA1CU2O8+DELTA CRYSTAL BOULES GROWN BY THE TRAVELING SOLVENT FLOATING-ZONE METHOD

We have grown Bi2Sr2Ca1Cu2O8+delta single crystals by the travelling solvent floating zone (TSFZ) method and measured the superconducting properties of various parts of grown crystal boules through Laue photographs, X-ray diffraction, resistivity and magnetization measurement. Generally, a part grown in an early stage shows metallic resistivity behavior, while a later part shows semiconducting behavior in a normal state and a lower superconducting transition temperature. However, after an,appropriate one-day annealing under nearly the same conditions as when it was grown, we could obtain a homogeneous Bi2Sr2Ca1Cu2O8+delta crystal boule by the TSFZ method.