Hematite mossbauer spectra

The soil close to the crater rim, at the exit point of Opportunity, shows a high hematite content in the Mossbauer spectrum (Fig. 8.36), which can be attributed to the presence of hematite spherules blueberries). 

Sb carrier ions. The Sb-119 ions were adsorbed on 30 mg of hematite from 10 cm3 of a 0.25 mol/dm3 KC1 solution containing about 1 mg of pentavalent Sb ions. About 0.3 mg of Sb was adsorbed at pH 2.5 and 4.0. The amounts of Sb adsorbed are less than that required to cover all the hematite surfaces as a monolayer. The emission Mossbauer spectra obtained are shown in Figure 7. It is seen from Figure 7 that the width of the emission Mossbauer spectrum at pH 2.5 is much smaller than that of the carrier-free one, while essentially no effect of carrier Sb ions is observed at pH 4.0. 

Two sextets assigned to the A and B sites, can be fitted to a broadened Mossbauer spectrum. For maghemite formed via reduction of hematite to magnetite, followed... 

Method 3 produces ca. 3 g of hematite. The sample prepared in 2 10 M HCl consists of subrounded crystals between 30-50 nm across (Fig. 10-1 c) with a surface area of around 30 m /g. In 10 M HCl the crystal size is around 150-200 nm (Fig. 10-1 d) and the surface area is only a few m /g. The X-ray peaks of the 0.002 M HCl product are somewhat broader than those of the material produced in 10 M HCl owing to the smaller crystal size. The Mossbauer spectrum at RT (Fig. 10-4) shows a sextet corresponding to a magnetic hyperfine field of 53.3 T. 

Murad E. and Schwertmann, U. (1986) Influence of A1 substitution and crystal size on the room-temperature Mossbauer spectrum of hematite. Clays Clay Min. 34 1-6. 

Properties XRD pattern, Mossbauer spectrum available [1318]. PZC/IEP of hematite-goethite composite is presented in Table 3.468. 

Figure 6. Mossbauer spectrum of an iron-rich muscovite from a western Maine metapelite (data from Guidotti et al. 1994). This samples contains 82% of its total Fe as Fe. Such a large amount of Fe might be expected because this muscovite coexists with both magnetite and hematite. Spectrum is newly collected data on the same mounts used by Guidotti et al. (1994). Data are of relatively poorer quahty because there is far less total Fe in muscovite.

The Mossbauer spectrum of the fly ash sample obtained from the Lethabo power plant consisted of a Fe and Fe component, typical of silica glass. In addition to the glass formation, hematite (Fe203) was also observed (see Fig. 30.12). The same spectrum was observed for the agglomerated coarse ash sample, but with a slightly different Fe /Fe ratio. 

After the HT-XRD experiments were conducted, a Mossbauer spectrum for each sample was obtained. The resulting Mossbauer spectrum yielded Fe-containing glass and hematite as shown in Fig. 30.12. The possible occurrence of the intermediate pyrrhotite phase, due to the decomposition of pyrite, was not observed. 

Fig. 3.10 Mossbauer spectrum of a hematite sample showing simultaneously AE and WF phases...

Fig. 3.38 Mossbauer spectrum at RT and at 80 K of a hematite-rich sample containing hematite and goethite...

Figure 4.73 Mossbauer spectrum of sample 3.5 hematite (blue), A (red) and B (dark red) sites of magnetite, as well as hydroxide (green) were identified...

Fig. 3.16 Schematic drawing of the MIMOS II Mossbauer spectrometer. The position of the loudspeaker type velocity transducer to which both the reference and main Co/Rh sources are attached is shown. The room temperature transmission spectrum for a prototype internal reference standard shows the peaks corresponding to hematite (a-Fe203), a-Fe, and magnetite (Fe304). The internal reference standards for MIMOS II flight units are hematite, magnetite, and metallic iron. The backscatter spectrum for magnetite (from the external CCT (Compositional Calibration Target) on the rover) is also shown...

The hydrolyzing role of oxide surfaces is very elegantly shown in Mossbauer investigations of the adsorption of Fe(Ill) on hematite a- Fc203 [19]. Since Fe is Mossbauer-inactive, the spectrum of ferric ions is not obfuscated by that of the particles. 

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