The effect of iron doping in La0.8Sr0.2Fe0.05Co0.95O3-δ perovskite

La0.8Sr0.257Fe0.05Co0.95O3-δ perovskite is investigated by 57Fe transmission and emission Mössbauer spectroscopy, X-ray diffraction, AC magnetic susceptibility and magnetotransport measurements. Temperature dependence of the 57Fe Mössbauer isomer shift, quadrupole splitting, magnetic hyperfine field, line broadening, and relative spectral area is presented in a detailed manner for La0.8Sr0.257Fe0.05Co0.95O3-δ . The oxidation state of iron is determined to be Fe3+, and the presence of preferential electronic charge compensation Fe3+ ↦  Fe4+ over that of Co3+ ↦ Co4+ is excluded. Relaxation of iron magnetic moments reflected by the 57Fe Mössbauer spectra of La0.8Sr0.257Fe0.05Co0.95O3-δ are interpreted as evidence for the existence of superparamagnetic like Co clusters and a corresponding cluster glass magnetic phase formed below T ≈65 K. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005