A Study Of The Single-Crystals With Nominal Composition Of Bi2sr2cacu2oy By Stem And Single-Crystal X-Ray-Diffraction

The structure and the composition of single crystals with the nominal composition Bi2Sr2CaCu2Oy have been studied by EDX and single crystal X-ray diffraction. The A.C. magnetic susceptibility measurements indicated that the superconducting transition temperature of these single crystals were ranging from 30K to 90K. The EDX elemental analysis showed that in general the actual composition of the single crystals deviated from the ideal composition Bi2Sr2CaCu2Oy. Partly substitution of Ca by Bi was frequently observed and, with the decreasing of the Ca content, the Tc of the single crystals decreased progressively from 90K to 30K. Single crystal x-ray diffraction indicated that the unit cell parameters of the single crystal, a, b and c, increase with the decrease of the Tc in the range of 65-90K.