EFFECTS OF 230 MEV AU-14 IRRADIATION ON BI2SR2CACU2OX

Bi2Sr2CaCu2Ox tapes were irradiated using 230 MeV Au14+ ions. Columnar defects were presumably produced due to irradiation. Zero-field-cooli ng (ZFC) magnetization increased up to a fluence of 1.6 X 10(11) Au+/c m(2), but field-cooling (FC) magnetization decreased, indicating the s trong pinning effects resulting from the columnar defects. The critica l current density as well as the irreversibility field, obtained from the hysteresis loops, were enhanced. Irreversibility fields are fitted by H-irr = A exp(-T/T-A). An effective activation energy for flux mot ion was obtained from the measurements of magnetization relaxation. Th e features of flux pinning as a result of the columnar defects were co mpared with those of point defects brought about by 120 MeV O7+ irradi ation.