Strontium ferrate

Strontium compounds, 23 319-324 estimated distribution of, 23 3201 world production of, 23 319-320 Strontium cyanide, 8 197 Strontium ferrate (1 1), 5 598 Strontium fluoride, 23 323 Strontium fluoroborate tetrahydrate, 4 153 Strontium halides, 23 323 Strontium hexaferrite, 23 323 Strontium hydride, 13 613 Strontium hydroxide, 23 324 Strontium iodide, 23 323 Strontium-lead alloys, 14 779 Strontium minerals, 23 320 producers of, 23 319 Strontium nitrate, 23 319, 321, 323 Strontium oxide, 23 318, 324 Strontium peroxide, 18 396, 23 324 Strontium-silicon alloy, 22 520 Strontium sulfate, 23 322, 324 Strontium sulfide, 23 322 Strontium titanate... 

Strontium perferrate, SrFe04, is obtained 4 by double decomposition of the potassium salt and a saturated, neutral solution of strontium bromide. The precipitate is washed with alcohol and ether. Obtained in this manner, the strontium ferrate is not pure, but contains admixed ferric oxide. It is deep red in colour, slightly soluble in water, and readily decomposed by acids. It is useful for preparing aqueous solutions 4 of the perferrates of the less common alkali metals—lithium, rubidium, caesium—of calcium and magnesium. 

DeganeUo F, Liotta LF, Longo A, Casaletto MP, Scopelletti M. Cerium effect on the phase stmeture, phase stability and redox properties fo ce-doped strontium ferrates. Solid State Chem. 2006 179 3406. 

Figure 15 shows spectra of strontium ferrate [7]. It is evident that SrFeOs is antiferromagnetic (AFM) below 134 K and gives a field gradient of 331 kG at 4K. Because of the perovskite type of structure the iron (III) symmetry is cubic and there is no quadrupole splitting effect from the nominal 3d Fe configuration. 

Strontium ferrate (SrFe03) has the classic perovskite structure just like lanthanum cobaltate (LaCo03). In SrFe03, iron is tetravalent and strontium is bivalent. In LaCo03, both lanthanum and cobalt are trivalent. Although these pristine compounds themselves are very interesting, some combinations of the two acquire even more exciting properties. 

Heating with the following solids, their fusions, or vapours (a) oxides, peroxides, hydroxides, nitrates, nitrites, sulphides, cyanides, hexacyano-ferrate(III), and hexacyanoferrate(II) of the alkali and alkaline-earth metals (except oxides and hydroxides of calcium and strontium) (b) molten lead, silver, copper, zinc, bismuth, tin, or gold, or mixtures which form these metals upon reduction (c) phosphorus, arsenic, antimony, or silicon, or mixtures which form these elements upon reduction, particularly phosphates, arsenates,... 

Although the dioxide FcOa has not been isolated with certainty, derivatives such as strontium ferrite,4 Sr0.Fe02, and barium ferrite, UaO.Fo()a, are known, corresponding to the manganites. Ferrates,5 corresponding in composition to the manganates, have also been obtained, the most stable of which is the barium salt, BaFe04. 

Hydrous iron(in) oxide is readily soluble in acids but also to a slight extent also in strong bases. When concentrated solutions of strontium or barium hydroxide are boiled with ferric perchlorate, the hexahydroxo-ferrates(in), M3[Fe(OH)6]2, are obtained as white crystalline powders. With alkali-metal hydroxides, substances of composition IV FeOz can be obtained these can also be made by fusion of Fe203 with the alkali-metal hydroxide or carbonate in the proper stoichiometric proportion. Moderate concentrations of what is presumably the [Fe(OH)6]3 ion can be maintained in strongly basic solutions. 

The barium ferrate(IV) phase is only partly related to the strontium compound as it has a hexagonal structure instead of the cubic perovskite structure... 

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