Oxygen-deficient perovskites

Grenier JC, Pouchard M, Hagenmuller P (1981) Vacancy Ordering in Oxygen-Deficient Perovskite-Related Ferrites. 47 1-25 Grice ME, see Politzer P (1993) 80 101-114... 

The magnetic properties of the new solid solution series SrFe Rui 3 3, (0 < X < 0.5) with distorted perovskite structure, where iron substitutes exclusively as Fe(in) thereby causing oxygen deficiency, has also been studied by Greenwood s group [147] using both u and Fe Mossbauer spectroscopy. Iron substitution was found to have little effect on the magnetic behavior of Ru(IV) provided that X remains small (x < 0.2). 

The most important of these are perovskite structure solids with a formula A2+b4+o3 that can be typified by BaCeC>3 and BaZrCV The way in which defects play a part in H+ conductivity can be illustrated by reference to BaCeCV BaCeC>3 is an insulating oxide when prepared in air. This is converted to an oxygen-deficient phase by doping the Ce4+ sites with trivalent M3+ ions (Sections 8.2 and 8.6). The addition of the lower valence ions is balanced by a population of vacancies. A simple substitution reaction might be formulated ... 

The same general approach can be applied to grossly non-stoichiometric oxides [8], For an oxygen deficient perovskite such as SrFeC>2.5 this involves an explicit... 

Shin, S Arakawa, H Hatakeyama, Y Ogawa, K Shimomura, K. Absorption of NO in the lattice of an oxygen-deficient perovskite SrFeOs.x and the infrared spectroscopic study of the system NO-SrFeOs.x. Mater. Res. Bull, 1979, Volume 14, Issue 5, 633-639. 

Oxygen-deficient perovskites that contain Mn have been shown to have Mn, Mn ", and Mn. The Mn is octahedrally coordinated, Mn is tetrahedrally coordinated, and Mn apparently exists in both and symmetries. " ... 

Grenier, J. C., Pouchard, M., Hagenmidler, P..-Vacancy Ordering in Oxygen-Deficient Perovskite-Related Ferrities. Vol. 47, pp. 1-25. 

Perovskites constitute an important class of inorganic solids and it would be instructive to survey the variety of defect structures exhibited by oxides of this family. Nonstoichiometry in perovskite oxides can arise from cation deficiency (in A or B site), oxygen deficiency or oxygen excess. Some intergrowth structures formed by oxides of perovskite and related structures were mentioned in the previous section and in this section we shall be mainly concerned with defect ordering and superstructures exhibited by these oxides. 

A significant step in the history of the HTSs was the discovery in 1966 of superconductivity in the oxygen-deficient perovskite SrTi03 5, containing some barium or calcium substituted for strontium. Although the Tc value was very low (0.55 K), in retrospect it can be seen as the first superconducting ceramic. In 1979 a Tc of approximately 13 K was discovered for BaPb075Bi025O3, which also has the perovskite structure. 

An interesting case79 of a perovskite with high oxygen-deficiency (x>0.5) where the B-metal is present in three different coordination environments is La3Ba3Cu6018 r Phases with varying y adopt a... 

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