Interest in creating magnetic metamaterials has led to methods for growing superstructures of nanoparticles. Mesoscopic crystals maghemite ($\gamma\text{-Fe}_2\text{O}_3$) nanoparticles can be arranged into highly ordered body-centered tetragonal lattices up a few micrometers. Although measurements on disordered ensembles have been carried out, determining the properties individual mesoscopic i...

Preparation of magnetitelmaghemite nanometric particles is reported from the precipitation of ferrous dodecyl sulfate micellar solution with methylamine. The size of nanocrystals is controlled by the micellar concentration and by temperature. It varies from 3.3nm to llnm. Magnetic properties are studied for various sizes of maghemite particles.

The conversion of magnetite to maghemite has been studied kinetically in the ultrafine particle range (77-220A) by chemical analysis. X-ray diffraction, and Mossbauer measurements. The reaction is third order. The activation temperatures are relatively low (8 250-1 1 200 K). Electron hopping in ultrafine magnetite powders is discussed on the basis of the results.

background: removing heavy metals from industrial wastewaters by iron nanoparticles has been much noticed in the recent years. chromium is considered as one of the emphasis environmental pollutants. there are high concentrations of chromium in the wastewater of electroplating industries. magnetic iron nanoparticles are used to control and eliminate the heavy metals from industrial effluents thr...

Fe2O3-Al2O3 compounds with different Fe/Al compositions were synthesized by coprecipitation (CP) method and calcined at 300°-1000°C. The formation of crystalline phases (e.g., maghemite, hematite), transformation temperature, specific surface area, lattice parameter, crystallite size, magnetic properties of iron oxide were all affected by the component ratio and thermal treatment.

Candida rugosa lipase immobilized on maghemite nanoparticles demonstrated high stereoselectivity in kinetic resolution of racemic carboxylates and improved long-term stability over its parent free enzyme, allowing the supported enzyme to be repeatedly used for a series of chiral resolution reactions.