Abstract
High quality stoichiometric brownmillerite-type oxide single crystals have been successfullygrown by the floating zone method using a mirror furnace. We report here on the growth conditionsand structural characterization of two model compounds: Ca2Fe2O5 and Sr2ScGaO5. Both showoxygen deficiency with respect to the average perovskite structure, and are promising candidates foroxygen ion conductivity at moderate temperatures. While Sr2ScGaO5 single crystals were obtainedin the cubic oxygen-deficient perovskite structure, Ca2Fe2O5 crystallizes in the brownmilleriteframework. Having no cubic parent high temperature counterpart, Ca2Fe2O5 crystals were found tobe not twinned. We report on structural characterization of the as-grown single crystals by neutronand X-ray diffraction, as well as scanning electron microscopy (SEM) coupled with EDX (EnergyDispersive X-Ray Spectroscopy) analysis and isotope exchange experiments.