Maghemite composition

Raman chemical imaging can be employed to access the homogeneity and the structural stability in terms of oxidation rates, onset of hematite, and organic contamination of as-precipitate and oxidized iron oxide samples. Oxidation-related Raman features have been established by comparative study of bulk oxides and nanoparticles attained in two different oxidation states, suggesting that the solid nanophase synthesized had a mixed magnetite-maghemite composition [52]. 

A detailed investigation about the chemical and structural composition of maghemite (diameters in the range of 10-20 nm) based MF samples, prepared through the oxidation of magnetite nanoparticle, the latter synthesized by the coprecipitation route, was reported [53]. The precipitate containing the... 

Eight different iron oxides have been identified in the weathering environment to date. They are goethite and hematite (common), lepidocro-cite, maghemite, ferrihydrite and magnetite (moderately widespread) and akaganeite and feroxyhyte (rare). These minerals often occur in close association. Since they have similar or even identical composition, a logical question is - under what conditions do the different oxides form ... 

PZC/IEP of maghemite-goethite composite is presented in Table 3.469. Properties Goethite and maghemite, BET specific surface area 135.2 m /g,... 

The name maghemite was first suggested in 1927. It is a combination of the first syllables of magnetite, which has the same structure, and hematite, which has the same composition. 

I.S. Smolkova, N.E. Kazantseva, K.N. Makoveckaya, P. Smolka, P. Saha, A.M. Granov, Maghemite based silicone composite for arterial embolization hyperthermia. Materials Science Engineering C, Materials for Biological Applications 48 (2015) 632-641. 

Prepared catalyst precursors were analyzed and characterized by conventional physical methods. Their nominal chemical composition before shaping is presented in Table 1. Table 2 is showing some characteristic physical data of catalyst precursors in the powder as well as in the pellet form. It has been foimd that an important characteristic is the total crystallinity and the ratio between a-Fe203 (hematite d = 1,84 A) and y-Fe203 (maghemite d = 2,95 A), determined from the XRD-pattem. 

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