Embedding of 211 particles in NEG-123 superconductors

We report on the embedding of insulating 211 particles into ternary 123 superconductors of the type (Nd0.33Eu0.33Gd0.33)Ba2Cu3Oy (NEG). It is found that the externally added 211 particles can act as nucleation sites in order to control the 211 particle size and distribution. As the composition of the added 211 particles also affects the superconducting NEG matrix, we varied the composition of the light rare earth (LRE) elements within the 211 particles while keeping the composition of NEG and the oxygenation procedure constant. Measurements of magnetization loops reveal that the position of the secondary peak can be shifted towards higher values on increasing the Gd content within the 211 particles, whereas the nominal largest J(c) values are achieved in the sample with an even LRE ratio. From a pinning force scaling analysis, we find that the peak in the pinning force diagrams can be shifted even up to 0.53, which indicates a further strengthening of the delta T-c-pinning mechanism.