Identification of superconducting phases in ceramic particles by magnetic field induced forces using a magnetized wire

A new equipment for minority phase analysis of superconducting (SC) phases within chemically inhomogeneous ceramic grains using a high gradient magnetic field or field induced effect of torque is presented. Single grains down to 20 mu m are either captured by a magnetized iron wire or identified because of their torque movement in a pulsed magnetic field. An assembly of many hundreds of grains can be investigated for minor quantities of SC phases from 80 K up to room temperature. A maximum field of up to 100-140 mT allows us to reliably identify SC grains and evaluate their SC critical temperatures T(c). Localization of SC grains allows us to extract them for further analysis. Experiments with YBa(2)Cu(3)O(2-delta) grains demonstrated that T(c). values evaluated in such a way are rather close to those, which are determined by magnetization measurements. (C) 2010 American Institute of Physics. [doi:10.1063/1.3449326]