Magnetic properties of titanomagnetites Fe3−xTixO4 (0≤x&amp;lt;1)

Ka̧kol, Z.; Sabol, J.; Honig, J. M.

doi:10.1063/1.348242

Cited by 25 publications

(38 citation statements)

References 16 publications

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“…6), the spontaneous magnetization increases initially with temperature and exhibits a maximum value for some temperature T, in the range 0oToT C . A similar variation has been observed experimentally [5,6]. This effect can be physically interpreted by considering the effect of the dominant antiferromagnetic AB coupling as follows: when the Ti concentration increases, we note that (a) Fe 2+ ions enter the tetrahedral sites (for x40.2); and (b) the fraction of Fe 3+ ions decreases faster at octahedral sites (Fig.…”

Section: Resultssupporting

confidence: 59%

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Temperature dependence of the magnetization of titanomagnetites

Lyberatos

2007

Journal of Magnetism and Magnetic Materials

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Section: Resultssupporting

confidence: 59%

“…The chemical composition of titamomagnetites has been studied extensively in the 1950's [3][4][5]. More recently, saturation magnetization measurements on single crystals have established that the cation distribution is [6,7] …”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of the magnetization of titanomagnetites

Lyberatos

2007

Journal of Magnetism and Magnetic Materials

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“…Intermediate composition titanomagnetites (0oxo1) are complex spinels, with three different metal cations and valence states (Fe 2 þ , Fe 3 þ and Ti 4 þ ), and significant work has been done with synthetic samples to deduce the degree, form and temperature dependence of cation order and to understand its effects on fundamental magnetic properties [1][2][3][4][5][6][7][8][9]12,[19][20][21][22] . In natural titanomagnetites, additional complexity is added by the common presence of substituted cations (for example, Al, Mg and Mn) and variable degrees of cation deficiency, and we are unaware of any previous studies linking changes in fundamental properties such as T C to reordering of the cation distribution in natural titanomagnetites.…”

mentioning

confidence: 99%

“…Ferrimagnetism in these materials arises from an antiferromagnetic coupling of the A and B sublattices of the inverse spinel structure, with a net spontaneous magnetization that is determined by the proportions and the valence states of the magnetic cations in the A (tetrahedral) and B (octahedral) sites [1][2][3][4][5][6][7][8][9][10][11][12] . The Curie temperature (T C ) is directly related to the strength of the exchange interactions within and especially between the sublattices, which in turn depend on the site occupancy of the magnetic cations [13][14][15] .…”

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confidence: 99%

Inferred time- and temperature-dependent cation ordering in natural titanomagnetites

et al. 2013

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Despite years of efforts to quantify cation distribution as a function of composition in the magnetite-ulvöspinel solid solution, important uncertainties remain about the dependence of cation ordering on temperature and cooling rate. Here we demonstrate that Curie temperature in a set of natural titanomagnetites (with some Mg and Al substitution) is strongly influenced by prior thermal history at temperatures just above or below Curie temperature. Annealing for 10 À 1 to 10 3 h at 350-400°C produces large and reversible changes in Curie temperature (up to 150°C). By ruling out oxidation/reduction and compositional unmixing, we infer that the variation in Curie temperature arises from cation reordering, and Mössbauer spectroscopy supports this interpretation. Curie temperature is therefore an inaccurate proxy for composition in many natural titanomagnetites, but the cation reordering process may provide a means of constraining thermal histories of titanomagnetite-bearing rocks. Further, our theoretical understanding of thermoremanence requires fundamental revision when Curie temperature is itself a function of thermal history.

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“…The behavior for titanomagnetite RT‐SIRM during cycling to low temperature is not well documented in the literature. However, the temperature dependence of its LT‐SIRM is observed to follow the temperature dependence of the anisotropy constant [ Kakol et al , 1991; Moskowitz et al , 1998], and the Verwey transition in single crystals is suppressed with a Ti content as little as 0.4% [ Kakol et al , 1994]. Therefore RT‐SIRM results in Figure 8b clearly demonstrate the presence of stoichiometric multidomain magnetite in the HD sample and magnetite particles that are more oxidized or much finer in the LD sample.…”

Section: Magnetic Characterization Of the Old Crow Tephra At Halfway mentioning

confidence: 93%

Magnetic properties of the Old Crow tephra: Identification of a complex iron titanium oxide mineralogy

2004

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[1] The mineralogy and grain-size distribution of the Fe-Ti oxide population of the Old Crow tephra bed, outcropping at the Halfway House loess deposit in central Alaska, are characterized through multiple low-and high-temperature magnetization experiments. The characterization is facilitated by heavy liquid separation of the bulk sample into a lowdensity (<2850 kg/m 3 , LD) and high-density (!2850 kg/m 3 , HD) fraction. Three phases of the magnetite-ulvöspinel solid solution series, Fe 3Àx Ti x O 4 , x = 0, 0.1, and 0.3 are identified along with one phase of the ilmenite-hematite solid solution series, Fe 2Ày Ti y O 3 , y = 0.83. All four phases are present in both density separates, where coarser grains dominate the HD sample and finer more oxidized grains dominate in the LD sample. Lowtemperature frequency dependence and field dependence of both the in-phase and quadrature components of magnetic susceptibility are found particularly useful in identifying the magnetic ordering temperature of titanohematite phases with y > 0.8 and may play an equally important role as magnetic indicator of titanomagnetite. Furthermore, we demonstrate the ability of low-temperature magnetism to locate a 1 mm thick tephra bed dispersed in loess over 10 cm depth, through the identification of very low concentrations of a titanohematite phase with y = 0.9. The potential for advancing regional correlation of sedimentary deposits through the identification of Fe-Ti oxides common to tephra beds by low-temperature magnetism is illustrated in this study.INDEX TERMS: 1540 Geomagnetism and Paleomagnetism: Rock and mineral magnetism; 1512 Geomagnetism and Paleomagnetism: Environmental magnetism; 1519 Geomagnetism and Paleomagnetism: Magnetic mineralogy and petrology; 8404 Volcanology: Ash deposits; 5109 Physical Properties of Rocks: Magnetic and electrical properties; KEYWORDS: low-temperature magnetism, frequency and amplitude dependence of AC susceptibility, ilmenite-hematite and magnetite-ulvospinel solid solution series, tephra, stratigraphic correlation

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Magnetic properties of titanomagnetites Fe3−xTixO4 (0≤x<1)

Cited by 25 publications

References 16 publications

Temperature dependence of the magnetization of titanomagnetites

Temperature dependence of the magnetization of titanomagnetites

Inferred time- and temperature-dependent cation ordering in natural titanomagnetites

Magnetic properties of the Old Crow tephra: Identification of a complex iron titanium oxide mineralogy

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