DETERMINATION OF TRANSITION CURVES OF HIGH-T(C) SUPERCONDUCTORS BY PHASE-CONTRAST MICROSCOPY

A new method which allows the detection of the superconducting phase t ransition of high-T(c) superconductors (HTSC) on a microscopic scale i s reported. Micro-size holes in thin foils of superconducting material are examined in a transmission electron microscope at varying tempera tures. The superconducting transition induces small changes in the ima ge intensity within the holes, which can be detected by using electron ic image analysis. Superconducting transition curves are then obtained for various types of high-T(c) superconductors and for given values o f the applied magnetic field.