Investigation of conductivity in the Sr(Fe1−xTix)Oy system by iron-57 Mössbauer spectroscopy

On the basis of our previous work electrical conductivity in the Sr(Fe1−xTix)Oy system (0.0≤x≤0.9,y≤3) has been further studied by means of Mossbauer spectroscopy. When 0.0≤x≤0.6, the concentration of Fe3+ (II) doublet relates to the final firing temperature and electrical conductivity of the materials is sensitive to the concentration of Fe3+ (II). Atx=0.25, the curve of the resistivity versus Ti contentx shows a local minimum which is observed for the first time. The results indicate that the coexistence of Fe4+ and Fe3+ in the same lattice leads to high conductivity; the conductivity increases when the Fe4 concentration approaches to that of the Fe3+ one. When the temperature is at 260 K and 230 K, the presence of the intermediate state showing quadrupole splitting has an effect on the conductivity of the materials.