LARGE CHANGE OF IRREVERSIBLE AND REVERSIBLE MAGNETIC-PROPERTIES BY TI-DOPED IN BI-2212

We demonstrate for the first time that Ti has been partially substitut ed in Bi2Sr2Ca1Cu2O8+X (Bi2212)single crystals by the traveling solven t floating zone method in concentrations of about 1 and 2at%. From hig h resolution electron microscopy (HREM) we discovered that a high dens ity of planar defects is created at ac-plane by the Ti doping. These d efects form effective pinning centers when the field is applied along the c-direction. In addition to dramatically changing the irreversible magnetic properties, it is also shown to significantly affect the rev ersible magnetic properties.