Magnetic susceptibility measurements as a function of temeperature and freqeuncy I: inversion theory

Egli, Ramón

doi:10.1111/j.1365-246x.2009.04081.x

Cited by 54 publications

(43 citation statements)

References 59 publications

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“…It is a basic assumption of this theory that T C is a material constant, depending only on chemical composition and crystal structure of the remanence-carrying minerals, and that the function M S (T) is a single-valued and invariant material property, governing not only magnetization intensities but also the scaling of temperature-dependent anisotropies and energy-barrier distributions [44][45][46][47][48][49][50][51][52][53] . When the T C is itself a function of thermal history, and when M S (T) depends on the time-and temperaturedependent degree of cation ordering, additional complexity is required in quantitative modelling of remanence blocking and unblocking.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2013

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“…[48] discussed in detail the limitations and recent advances in the development of superparamagnetic iron oxide nanoparticles for hyperthermia. Egli [47] provided a useful comparison for the analysis of SPIONs and provided a self-consistency check of existing theories on magnetic relaxation phenomena using the susceptibility inversion. The physical, magnetic and heating characteristics of magnetite nanoparticle suspensions with average diameters of 12.5 and 15.7 nm were discussed in detail by Suto et.…”

Section: Experimental/theoretical Modelling Studies Of Magnetic Nanopmentioning

confidence: 99%

“…Considerable efforts have also been made in recent years to optimize material properties for magnetic hyperthermia applications [46,47]. Due to the complexity of the problem, several aspects pertaining to the combined influence of different parameters such as those associated with the geometry, concentration and absorption rate of the nanoparticles and the period of thermal ablation of tumour cells, are still unclear.…”

Section: Experimental/theoretical Modelling Studies Of Magnetic Nanopmentioning

confidence: 99%

A review on hyperthermia via nanoparticle-mediated therapy

et al. 2017

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“…Many methods have been developed to invert magnetization or susceptibility data that has been recorded as a function of temperature [61,62], and a short summary is presented in [63]. Using AC susceptibility as a function of temperature has the advantage that both temperature and time are considered in modeling the particle size distribution.…”

Section: Particle Sizementioning

confidence: 99%

Magnetic Measurements and Characterization

Hirt

2016

Iron Oxides

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IntroductionWhen characterizing the magnetic properties of iron oxides, whether they be geological or synthetic, there are four main factors that are of interest: (i) composition of the iron oxides; (ii) concentration in a bulk material; (iii) particle size distribution; and (iv) magnetic interaction between particles. These four factors are important because they govern the magnetic behavior that affects the usefulness of an iron oxide in any specific application. For example, composition can provide information about the provenance of the iron oxide minerals in a rock, sediment or soil, or the chemical stability of a synthesized nanoparticle. Particle size plays an important role in the magnetic properties of an iron oxide. Where some applications require superparamagnetic behavior, that is, only carries a high spontaneous magnetization in an applied field, others require that the material carry a stable remanent magnetization. Particle size is related to magnetic interaction between particles because interacting particles may behave collectively as a single larger particle.The magnetic properties that are most often used to characterize a material are susceptibility, saturation magnetization, coercivity, and Curie (T C ) or Néel (T N ) temperature. Remanent properties, that is, saturation remanent magnetization and remanent coercivity are also important in materials that can carry a permanent magnetization. This chapter focuses on methods that are commonly used to measure and characterize the magnetic properties of materials. First, the magnetic properties of the most common iron oxides and hydroxides are summarized; more detailed information on mineralogy, crystal structure, and magnetic properties can be found in several textbooks [1][2][3][4]. Methods for characterization can be divided into two types; those that measure induced magnetization, that is, measurements made in an applied field, and those that measure remanent magnetization, that is, in absence of an applied field. The latter are only useful for ferromagnetic materials that carry a permanent magnetization. The final section of this chapter reviews methods in interpreting magnetic properties alone or in combination.Iron Oxides: From Nature to Applications, First Edition. Edited by Damien Faivre.

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Magnetic susceptibility measurements as a function of temeperature and freqeuncy I: inversion theory

Cited by 54 publications

References 59 publications

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

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

A review on hyperthermia via nanoparticle-mediated therapy

Magnetic Measurements and Characterization

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