Abstract
Large crystals have been grown by a melt-processing technique from material with the starting composition that had been doped with , Pt and . The crystals have been investigated using a number of different techniques and for the undoped and those doped with Y/Nd(211) and/or Pt there is no evidence for substituting on sites. Crystals doped with show a second peak on the magnetization curve but in all cases the highest critical current densities measured with was and at 0 and 1 T, respectively. To enhance at high magnetic fields further doping materials and changed melt-processing conditions are being studied to bring about either substitution and/or a homogeneous distribution of very small Y/Nd(211) particles.