Hematite nanophase

Morris et al. (1991) obtained hematite of very small particle size ( 10 nm), termed nanophase by slow thermal decomposition in air of tri-Ee -acetato-hy-droxy-nitrate. XRD shows only two broad lines as in a 2-line ferrihydrite, but the magnetic hyperfine field at 4.2 K of 50.4 T appears to be more in agreement with poorly crystalline hematite. Well-crystalline hematite and Al-hematite were produced by decomposing Ee-Al-oxinates at 700 °C (da Costa et al. 2001). 

Morris, R.V. Lauer, H.V.Jr. (1990) Matrix effects for reflectivity spectra of dispersed nanophase (superparamagnetic) hematite with application to Martian spectral data. J. Geophys. Res. 95 5101-5109... 

Mars 1.5 78.3 6,796 280 0.01 Mafic silicates in daik regions, pyroxenes detected locally, olivine suspected Fe3t phases in bright regions probably include nanophase hematite and sulphate phases these and clay silicates in global dust are oxidative weathering products HjO (frost) condensates ice at north pole dry ice (C02) at south pole. 

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]. 

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