2013
DOI: 10.1590/s0100-06832013000600013
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Structural and magnetic characterization of maghemites prepared from Al-substituted magnetites

Abstract: SUMMARYSynthetic aluminum-substituted maghemites were characterized by total chemical analysis, powder X-ray diffraction (XRD), Mössbauer spectroscopy (ME), and vibrating sample magnetometry (VSM). The aim was to determine the structural, magnetic, and hyperfine properties of γ γ γ γ γ-Fe 2-x Al x O 3 as the Al concentration is varied. The XRD results of the synthetic products were indexed exclusively as maghemite. Increasing Al for Fe substitution decreased the mean crystalline dimension and shifted all diffr… Show more

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Cited by 12 publications
(4 citation statements)
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“…Dimension a values were close to the expected for cubic Mh (a = 0.8350 nm) (Eggleton, 1988), consistent with values estimated after Rietveld refinement by Poggere et al (2018). The values indicate heterogeneity in Mh particle size, which is mainly conditioned by the IS process in the crystal structure (Schulze and Schwertmann, 1984;Batista et al, 2013). According to the values of dimension a (<0.8329 nm) and MCS Mh220 (<31 nm), the Mh presents high IS (Batista et al, 2013).…”
Section: Mineralogical Studysupporting
confidence: 83%
See 1 more Smart Citation
“…Dimension a values were close to the expected for cubic Mh (a = 0.8350 nm) (Eggleton, 1988), consistent with values estimated after Rietveld refinement by Poggere et al (2018). The values indicate heterogeneity in Mh particle size, which is mainly conditioned by the IS process in the crystal structure (Schulze and Schwertmann, 1984;Batista et al, 2013). According to the values of dimension a (<0.8329 nm) and MCS Mh220 (<31 nm), the Mh presents high IS (Batista et al, 2013).…”
Section: Mineralogical Studysupporting
confidence: 83%
“…The values indicate heterogeneity in Mh particle size, which is mainly conditioned by the IS process in the crystal structure (Schulze and Schwertmann, 1984;Batista et al, 2013). According to the values of dimension a (<0.8329 nm) and MCS Mh220 (<31 nm), the Mh presents high IS (Batista et al, 2013). Since ferrimagnetic particle size determines the type of magnetic behavior, the Mh showed superparamagnetic behavior (<30 nm), which explains the high values of dependent frequency χ fd (>14 %) (Dearing, 1999).…”
Section: Mineralogical Studymentioning
confidence: 99%
“…Maghemite is a cation-deficient spinel with Fe 3+ in both the A and B sites. The contributions from Fe 3+ in the A and B sites of magnetically ordered maghemite lead to the Mössbauer spectrum that consists of two sextets with similar B hf values of ~50 T (somewhat lower than that of hematite), essentially zero ε values [51] and different values of δ. Aluminum can be incorporated in the structure of maghemite [45,51] just as in that of hematite, leading to a systematic decrease in B hf values and line broadening.…”
Section: Mössbauer Spectroscopymentioning
confidence: 99%
“…Microcline is an aluminosilicate of the feldspar family, a melting component in clays, and contributes to the plastic characteristic of clay[39]. In the XRD test, it was not possible to differentiate the Magnetite phase (Fe 3 O 4 ) from the Maghemite phase (γ-Fe 2 O 3 ), since they have the same crystallographic structure, which is why the diffractogram brings Magnetite as a result, as it took into account the sheet that eliminated the diffraction peaks during the analysis[40]. The diffractogram in Figure 3, the result of the mineralogical analysis of the fiber cement powder, identifies the phases Calcium Silicate Oxide (Ca 3 (SiO 4 )O-PDF 01-070-1846; 2θ = 15.8 • (011), 17.9 • (101), 22.9 • (110), 29.5 • (012), 32.3 • (200), 34.0 • (021), 36.1 • (112), 39.5 • (202), 43.3 • (211), 47.1 • (301))), Calcium Silicate (Ca 2 (SiO 4 )-PDF 01-083-0464; 2θ = 47.7 (212), 48.7 • (201), 50.8 • (312), 54.3 • (213), 60.6 • (200)) and iron sulfite (FeS-PDF 01-080-1026; 2θ = 43.2 • (311), 47.7 • (213), 57.9 • (231))…”
mentioning
confidence: 99%