Hematite synthesis routes

Morphologies of synthetic hematite include plates and discs, rods, spindles, spheres, ellipsoids, double ellipsoids, rhombohedra, stars, cubes and peanuts. In the absence of additives, hexagonal plates, which are often rounded, and rhombohedra predominate. Each morphology can be obtained by more than one synthesis route. Two common ways of producing idiomorphic hematite crystals in aqueous systems... 

Iron(III) oxide crystallizes independently of the synthesis route in the a-modification (hematite) after calcination. Brilliant, intense colors are obtained with 50-250 nm layers of Fe203. Absorption and interference colors are formed simultaneously and vary with layer thickness of iron oxide. Especially, the red shades are extremely intensive because interference and absorption enhance each other (Fig. 79). It is possible to produce an intense green-red flop with different viewing angles at a layer thickness similar to a green interference [5.228]. 

Iron oxide nanoparticles are undoubtedly one of the most investigated nanoparticles owing to their importance in industrial and medical appUcations. Hematite nanoparticles are comparatively more stable and therefore have wider applications as well. While several methods are available for the synthesis of nanoparticles, the green synthesis routes are preferred, more so iu biological apphcations. It has beeu demoustrated that natural products such as polysaccharides can be employed as effective templates, both through sacrillcial and otherwise routes to generate mono-dispersed nanoparticles of below 20 run. Such methods are easy to adopt for other ferrite nauoparticles as well. Incidentally, some of the polysaccharide methods are facile and possibly simple for rephcation at industrial scales. 

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