Oxygen-ion and electron conductivity in Sr2(Fe1−xGax)2O5

High-temperature electrical conductivity measurements, structural data from powder X-ray diffraction and 57Fe Mössbauer spectroscopy were combined to study the interrelationship of oxygen ion transport and p- and n-type transport in Sr2(Fe1−xGax)2O5, where x=0x=0, 0.1 and 0.2. Although gallium substitution generally decreases the total ion-electron transport, the transition of the orthorhombic brownmillerite structure to a cubic phase on heating results in the recurrence of the conductivity to the same high level as in the parent ferrite (x=0x=0). The changes of the partial contributions to the total conductivity as a function of x are shown to reflect a complicated interplay of the disordering processes that develop in the oxygen sublattice on heating in response to replacement of iron with gallium.

The 57Fe Mössbauer spectra for Sr2(Fe1−xGax)2O5 at 80 K: =0=0 (a) and =0.2=0.2 (b).Figure optionsDownload as PowerPoint slide