Mössbauer spectroscopy, X-ray diffractometry, ESR and electrical resistivity measurements, were used to study high Tc (above 100 K) superconducting materials in order to get information about the effect of the preparation circumstances as well as about the anomalous behaviour in57Fe and119Sn doped TlBaCaCu(57Fe)O4.5+δ and TlBaCuCu(119Sn)O4.5+δ superconductors. We have found that the Mössbauer parameters strongly depend on the preparation circumstances. In many cases the presence of Mössbauer lines of nonsuperconducting oxide phases indicated that the iron and tin could not entirely built in into the lattice of superconductor. Four valence state tin and four valence state iron sites were identified in the superconducting phases. We have found anomalous temperature dependent changes in the57Fe Mössbauer spectra of TlBaCaCu(57Fe)O4.5+δ samples around the Tc between 105-135 K. In this temperature range the total area of the spectrum temporary increases.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics
- Condensed Matter Physics
- Physical and Theoretical Chemistry