Studies of Structural Properties and Their Relationship to Critical Parameters in Superconducting Materials

摘要

The project comprised an experimental study of the electronic and vibrational properties of superconducting materials by means of Mossbauer spectroscopy. From the temperature dependence of the Mossbauer parameters of tin in the oxide superconductor Ba(Pb0.67Sn0.03)Bi0.3O3, phonon softening, characteristic of displacive transitions, was found to take place above the superconducting transition temperature. This observation is hence important for understanding the superconducting properties of the perovskite compounds. The Mossbauer effect at Sb121 in BaPb1-x(Bi,Sb)xO3 shows that Sb is 5+. The range of stability of the perovskite compounds was determined in the ternary systems Ba(Pb-Sn-Bi)O3 and Ba(Pb-Sb-Bi)O3. The composition dependence of the superconducting transition temperature was determined for both ternary systems. Conversion Electron Mossbauer Spectroscopy has been applied to the study of Nb3Sn superconducting films. This total has been found to provide a unique probe of the electronic and vibrational properties of thin film materials.