Effects of nanosize MgO additions to bulk Bi2.1Sr1.7CaCu2Ox

Nanosize MgO particles were added to Bi2.1Sr1.7CaCu2Ox (Bi-2212) powder in various molar fractions. Bulk samples were made from the MgO/Bi-2212 and heat treated by partial-melt processing. Scanning electron microscopy and energy-dispersive X-ray spectra were used to study the phases present in the samples. The effects of the MgO additions on the flux pinning behavior as a function of magnetic field and temperature were investigated by magnetization hysteresis measurements obtained with a SQUID magnetometer and a 33 T vibrating sample magnetometer. It was found that the nanosize MgO addition did not affect T-c of Bi-2212, while significantly expanding the magnetization hysteresis loops and increasing the irreversibility field. X-ray and SEM analysis suggested that MgO is inert with respect to Bi-2212. (C) 1998 Elsevier Science B.V.