Studies on Structural, Magnetic and Thermal Properties of xFe2TiO4-(1−x)Fe3O4 (0≤x≤1) Pseudo-binary System

Sorescu, Monica; Xu, Tianhong; Wise, Adam; Díaz-Michelena, Marina; McHenry, Michael E.

doi:10.1016/j.jmmm.2011.12.012

Cited by 29 publications

(16 citation statements)

References 38 publications

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“…The  values deviate from the diagnostic value (0.9 mm/s) reported for well-ordered, synthesized ulvöspinel where iron exists only as ferrous ion (Soresu et al 2012). This suggests that the ulvöspinel of the olivine basalt has undergone oxidation.…”

Section: +contrasting

confidence: 68%

“…This suggests that the ulvöspinel of the olivine basalt has undergone oxidation. Ulvöspinel tends to oxidize to magnetite plus ilmenite during subsolidus alteration of the host rocks (Wikipedia Foundation, Inc., 2013), causing significant changes in the hyperfine parameters (Soresu et al 2012). As shown in Table 1, ΔE Q values for the pyroxene-, olivine-, and ulvöspinel doublets increase with decreasing temperature from 297 K to 77 K. The  values for the pyroxeneand olivine doublets also increase in the same direction.…”

Section: +mentioning

confidence: 99%

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Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Hassan

Dekan

2013

Mineralogia

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Abstract. Olivine basalts from southern Egypt were studied by 57 Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe 2+ ), and a weak ferric (Fe 3+ ) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe 2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe 3+ /ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

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Section: +contrasting

confidence: 68%

Section: +mentioning

confidence: 99%

Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Hassan

Dekan

2013

Mineralogia

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“…isomer shift and quadrupole splitting, suggest that they can be dispersed in iron-bearing paramagnetic aluminosilicate glass ( Table 2 ing paramagnetic behaviour at room temperature, is supposed to be the result of the substitution of Fe 3+ by Ti 4+ (and the consequent reduction of Fe 3+ to Fe 2+ to maintain a charge balance) as stated in the structure of titanomagnetite (Sorescu et al 2012). Eventually, due to possible coexistence of both Fe 3+ and Fe 2+ in the same (octahedral) structural site, an average oxidation state of 2.5+ can be assumed.…”

Section: The Results Of the Mössbauer Spectroscopy Studiesmentioning

confidence: 99%

“…Eventually, due to possible coexistence of both Fe 3+ and Fe 2+ in the same (octahedral) structural site, an average oxidation state of 2.5+ can be assumed. This hypothesis was investigated by Sorescu et al (2012), studying the effect of progressive substitution of iron by titanium in a titanomagnetite solid solution in the pseudo-binary system Fe 2+ 2 TiO 4 -Fe 2+ Fe 3+ 2 O 4 , synthesised at high temperatures. They observed a gradual decline of the strength of the hyperfine magnetic field with an increasing content of Fe 2 TiO 4 and the appearance of a broad quadrupole doublet instead of magnetic sextet.…”

Section: The Results Of the Mössbauer Spectroscopy Studiesmentioning

confidence: 99%

Phase transitions of ferruginous minerals in the course of thermal processing of feldspar-quartz raw materials from the Sobótka region (Lower Silesia)

Lewicka¹

2017

Gospodarka Surowcami Mineralnymi

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This paper presents the results of analyses of feldspar-quartz raw materials from deposits of leucogranites located in the Sobótka region. This is a successive stage of research carried out by the author on reasons for colour variation of ceramic materials obtained from them. This step encompassed the firing of sample pairs of analogous chemical composition in different conditions: in a standard cycle lasting more than 2 hours (at a maximum temperature of 1200°C), and a fast one - lasting around 50 minutes (at a max. temperature of 1260°C). The obtained ceramic bodies were analysed using the XRD method, scanning microscopy SEM-EDS and57Fe Mössbauer spectroscopy at room temperature. The XRD investigations revealed the presence of quartz in both samples, while remnants of sodium feldspar were observed in the one fired in the fast cycle. The scanning microscopy confirmed that the principal component of the examined bodies is the aluminosilicate melt, resulting from the thermal decomposition of mainly feldspars and quartz. Single quartz grains and other minerals of high melting temperatures, i.e. zirconium, were also observed in the course of microscopic examinations. Products of other mineral phases’ transformations at high temperature, such as: titanomagnetite (spinel Fe-Ti), magnetite, biotite, xenotime, sphalerite as well as probably chlorites and garnets, were also relatively frequent. Mössbauer studies demonstrated the presence of three basic components constituting 30% (each) of the spectra, i.e. Fe2O3(presumably hematite), Fe3+ions (dispersed in aluminosilicate glassy phase), and nanocrystalline or amorphous oxide phase of iron (Fe-O). Some relatively small amounts (5 and 10%) of mixed valence iron cations (Fe2+/3+) that are not expected to influence the colour difference between samples after firing were also found. A paramagnetic doublet referring to them can be attributed to a titanomagnetite spinel or products of its thermal decomposition. The above-mentioned observations and examinations lead to the finding that the main reason for colour variation in the examined bodies as well as their different microstructure and advancement of phase transitions in the course of firing are different conditions of thermal treatment. These probably also influenced the forms in which iron and other colouring elements occur in the samples studied.

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“…In low-Ti TMs (x < 0.25), room-T Mössbauer spectra are generally found to contain three sextets (Hamdeh et al, 1999;Jensen & Shive, 1973;Sorescu et al, 2012;Tanaka & Kono, 1987). Two of these correspond to the sextets of pure magnetite, representing (1) A-site Fe 3+ (IS = 0.3 mm/s, QS = −0.02, B HF = 49 T, A = 33.3%) and (2) B-site Fe 2.5+ (IS = 0.67, QS = 0, B HF = 46 T, A = 66.6%).…”

Section: Fine-scale Chemical Heterogeneitymentioning

confidence: 99%

Curie Temperature Enhancement and Cation Ordering in Titanomagnetites: Evidence From Magnetic Properties, XMCD, and Mössbauer Spectroscopy

Bowles

Lappe

Jackson

et al. 2019

Geochem Geophys Geosyst

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Previous work has documented time‐ and temperature‐dependent variations in the Curie temperature (Tc) of natural titanomagnetites, independent of any changes in sample composition. To better understand the atomic‐scale processes responsible for these variations, we have generated a set of synthetic titanomagnetites with a range of Ti, Mg, and Al substitution; a subset of samples was additionally oxidized at low temperature (150 °C). Samples were annealed at temperatures between 325 and 400 °C for up to 1,000 hr and characterized in terms of magnetic properties; Fe valence and site occupancy were constrained by X‐ray magnetic circular dichroism (XMCD) and Mössbauer spectroscopy. Annealing results in large (up to ~100 °C) changes in Tc, but Mössbauer, XMCD, and saturation magnetization data all demonstrate that intersite reordering of Fe2+/Fe3+ does not play a role in the observed Tc changes. Rather, the data are consistent with vacancy‐enhanced nanoscale chemical clustering within the octahedral sublattice. This clustering may be a precursor to chemical unmixing at temperatures below the titanomagnetite binary solvus. Additionally, the data strongly support a model where cation vacancies are predominantly situated on octahedral sites, Mg substitution is largely accommodated on octahedral sites, and Al substitution is split between the two sites.

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Studies on Structural, Magnetic and Thermal Properties of xFe2TiO4-(1−x)Fe3O4 (0≤x≤1) Pseudo-binary System

Cited by 29 publications

References 38 publications

Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Phase transitions of ferruginous minerals in the course of thermal processing of feldspar-quartz raw materials from the Sobótka region (Lower Silesia)

Curie Temperature Enhancement and Cation Ordering in Titanomagnetites: Evidence From Magnetic Properties, XMCD, and Mössbauer Spectroscopy

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