Heavy ions irradiation effects in high Tc superconductors: Mossbauer study of Fe-doped 1.2.3 phases YBa2Cu3−xFexO7−δ irradiated by 3.5 GeV–xenon ions

3.5 GeV-Xenon ions-induced defects in Fe-doped 1.2.3 phases YBa2Cu3-xFexO7−δ with x = 1, 0.3 and 0.45 have been investigated by means of in situ resistance measurements at 100 K and Mossbauer spectroscopy at 300 K. Beside the exponential dependence of the resistance with Xe-fluence, the radiation effects result in the appearance on the Mossbauer absorption spectra of a fourth quadrupole doublet D4 (δ≈0.3 mm/s, ΔQ4 ≈ 1.1 mm/s) whose relativeintensity increases with dose i.e. with latent track density. Concerning the distribution of Fe Species on Cu sites in the unperturbed part of the sample, a strong interrelation between the variations of the relative areas of quadrupole doublets D1 (ΔQ1 ≈ 1.1 mm/s) and D3 (ΔQ3 ≈ 0.3 mm/s) under irradiation lead us to assign the corresponding Fe species substituted on Cu(1) sites ([CuO2]∞ chains of corner sharing CuO4 groups), in agreement with heat treatment analysis.