Use of the ac inductive method to assess the quality of bulk melt texturedsuperconductors

Through a measurement of flux profiles, the inductive method of Campbell ha s not only been used for determining the hulk critical current density of l arge sized samples but has also been extended to study the coupling strengt h of the domains in melt textured NdBa2Cu3O7 - delta superconductors. An an alysis of the profiles measured for the slow (1 degrees C/h) and fast coole d (40 degrees C/h) samples through peritectic temperature, T-p clearly show ed that the domain boundaries in the fast cooled samples are decoupled in t he presence of external de fields. The observed features of flux profiles a re correlated to the microstructural features of the samples. It is propose d that this technique can be used routinely to assess the quality of large size melt textured samples for high current applications Like magnetic bear ings or quasi permanent magnets. (C) 2000 Elsevier Science B;V. All rights reserved.