Iron oxides spinel-type

For all these reasons an increase in chromium concentration may be the best solution to increase the sulphidation resistance of iron-aluminium alloys. The present work has shown that chromium has a very beneficial effect on the sulphidation resistance in oxygen deficient gases. Such improvement of sulphidation resistance in H2S environments has also been found in nickel-aluminium alloys, where the corrosion rate decreased significantly, when 8 wt% chromium were added [22], Whether chromium increases the rate of alumina formation or contributes to the formation of protective spinell type oxides Fe(Cr,Al)203 cannot be decided from the available results. It is also possible that chromium catalyses the transition from a less to a more protective type of A1203. It was for example found that chromium enhances the transition from 0-Al2O3 to a-Al203 in Ni-Al at temperatures above 1000°C [30],... 

Well-ordered macroporous spinel-type and perovskite-type mixed iron oxide, Eai x Srx Ee03 and MFe204 (M = Ni, Zn, Co, Nii.x Zn ) can be prepared using a mixed metal nitrates solution in mixed solvent of EG and methanol.Ordered macroporous layered double... 

A = Mg, Fe, NT, Co, and Zn and trivalent cations B = Al, Fe, Cr, and V L Hence two types of spinel structure must be distinguished normal spinels withx = 0, meaning that all the divalent cations occupy tetrahedral sites, and inverse spinels with x = 1. Of these, rods of pure magnetite (Fe OJ or its doped form" obtained by casting molten iron oxides have been used as industrial anodes since 1870. Apart from magnetite and ferrites, today other classes of spinels have been investigated such as cobaltites and chromites. Due to their better electrocatalytic properties and fewer health and safety issues, cobaltites (e.g., MCo O with M= Mg, Cu, and Zn) are now preferred and are the only ones being developed. 

Magnehc nanoparticles have been synthesized with a number of different composi-hons and phases, including iron oxides, such as Fe O and y-Fe203, pure metals, such as Fe and Co, spinel type ferromagnets, such as NiFe O, MuFejO/ ", as weU as alloys, such as CoPtj - and FePt. ... 

---