A dependence of structural transformation and iron exsolution on chemical environment and reducing conditions is proven for the perovskite La0.6Sr0.4FeO3−δ.

Although γ/η-Mo4O11 and Mo2Ta2O11 are used in a variety of industrial applications and can easily be synthesized in a chemical vapour transport (CVT) process or reactions in silica ampoules, respectively, only few data are available concerning their physical properties. In this paper, we further explore the properties of the three compounds with respect to their thermal and magnetic behavior, surface composition, and Raman spectroscopic properties.

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The iron exsolution behavior of lanthanum strontium ferrite under reducing conditions is investigated using multiple ex situ and in situ methods. During heating experiments, an irreversible phase transition in oxygen-deficient environments from the rhombohedral to the cubic polymorph is witnessed in the form of a non-linear shift of the reflexes prior to the exsolution of metallic iron. Since this is not the case in oxidative environments, it leads to the conclusion that oxygen vacancies in the lattice stabilize the cubic phase. Also, the exsolution is shown to exhibit an Avramilike behavior, suggesting a diffusion-limited process, where the transport of iron to the Fe-depleted surface-near region is the slowest step.

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