The effects of Ce-based additions (CeO2andBaCeO3) in combination with MgO additions on the magnetic properties of melt texturedYBa2Cu3O7−&dgr;have been investigated. The additions lead to improvements in the magnetic properties ofYBa2Cu3O7−&dgr;compared to samples with either addition alone or with no additions. The Ce–Mg addition combination produces a “peak effect” in the magnetic hysteresis loop without significantTcdegradation. This is postulated to be due to the formation of a new type of pinning center. Both Ce and Mg ions are thought to substitute in theYBa2Cu3O7−&dgr;lattice, creating defects that produce a peak effect in the magnetic hysteresis loop. Mg additions alone lead to a reduced Tc, while Ce additions restore the Tc and enhance the magnitude of the peak. ©1997 American Institute of Physics.