INVESTIGATION OF THE ELECTRICAL-RESISTIVITY BEHAVIOR BETWEEN THE KOSTERLITZ-THOULESS TEMPERATURE AND THE GINZBURG-LANDAU TEMPERATURE IN SPRAY-DRIED BULK BI2SR2CACU2O8- THE ROLE OF 2-DIMENSIONAL FLUCTUATIONS AND DEFECTS(D )

The resistive transition R(T) between the Kosterlitz-Thouless temperat ure and the Ginzburg-Landau temperature was studied in spray-dried bul k Bi2Sr2CaCu2O8+d superconductors for a magnetic-field range between 0 and 0.3 T. The samples were prepared by the spray-drying technique wi th Bi2+xSr2-x-yCa2+yCu2O8+d for x = y = 0.05 or 0.1 as a starting comp osition here. The data analysis was performed assuming various resisti ve laws previously proposed. When numerically analyzed in terms of a t wo-dimensional Kosterlitz-Thouless theory the results lead to remarkab le quantitative agreement. This implies that the R(T) behavior can be described within a picture of a highly two-dimensional behavior of mac roscopic fluctuations of vortex-antivortex depairing type. The role of defects or inhomogeneities in the resistive behavior is outlined.