Mössbauer spectroscopy on57Fe in highT c superconductor Bi2Sr2Ca1Cu2O y

Mössbauer measurements were performed on polycrystalline⁵⁷Fe: Bi₂Sr₂Ca₁Cu₂O _y , super-conductor in the temperature range of 77–296 K. The samples were obtained in a solid phase synthesis using 0.01, 0.03, 0.1 and 0.5 mol fractions of α-Fe₂O₃ (96% enriched in⁵⁷Fe). A prevailing quadrupole doublet practically independent of temperature and iron concentration characterizes the obtained Mössbauer spectra. The corresponding hyperfine parameters suggest the presence of high spin Fe¹¹¹ ions in a strongly distorted octahedral symmetry which indicates a probable copper substitution by iron in the system.