Stable tetragonal HTSC Fe-doped 1-2-3 phase with oxygen excess

Mössbauer study was performed on the YBa2Cu2.95Fe0.05Oy compound prepared in three different states: orthorhombic phase with y?7, tetragonal non-superconducting phase with oxygen deficiency, and a new tretragonal superconducting phase with oxygen excess (y>7). The new synthesis method was used for preparation of the Fe-doped YBa2Cu3Oy (named 1-2-3) compound. The comparison of Mössbauer spectra of three different states allowed us to identify the oxygen environments of the Fe atoms in the Cu1 positions.