Nanomagnetism and spin electronics: materials, microstructure and novel properties

Krishnan, Kannan M.; Pakhomov, A. B.; Bao, Yuping; Blomqvist, Peter; Chun, Yeoun Sook; Gonzales, Marcela; Griffin, Kelli; Ji, Xiaosong; Roberts, Bradley K.

doi:10.1007/s10853-006-6564-1

Cited by 208 publications

(146 citation statements)

References 88 publications

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“…Thereafter, the crystallite sizes of CoFe 2 O 4 powders were estimated to be 30 nm, 65 nm, and 82 nm for particles annealed at 400 °C, 850 °C and 1000 °C, respectively. (d cr > 100 nm [13]) as a result of the recrystallization process when the grain growth is accomplished by the replacement of original deformed crystallites by un-deformed one.. However, recrystallization leads to a polycrystalline behavior of particles and a wide distribution of particle sizes as it is confirmed by TEM results (Fig.…”

Section: Particle Structure Characterizationmentioning

confidence: 54%

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

et al. 2014

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Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the solgel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of particles determined by X-ray diffraction as well as particle size observed via transmission electron microscopy increased with annealing temperature. The magnetic properties observed via vibrating sample magnetometer showed that an increase in the annealing temperature leads to the increase in the magnetization saturation and, in contrast, a decrease in coercivity. The effect of annealing on magnetic properties of ferrite particles has been explained by the recrystallization process at high temperature resulting in grain size growth and decrease in an imposed stress relating to defects of crystal lattice structure of nanoparticles. The magnetorheological characteristics of suspensions of ferrite particles in silicone oil were measured using a rotational rheometer equipped with a magnetic field generator in both steady shear and small-strain oscillatory regime. The magnetorheological performance expressed as a relative increase in magnetoviscosity appeared to be significantly higher for suspensions of particles annealed at 1000 C.

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Section: Particle Structure Characterizationmentioning

confidence: 54%

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

et al. 2014

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“…MNPs were synthesized in our labs according to procedures detailed in previous work. 2,[7][8][9][10] Commercial samples from two different vendors were diluted to concentrations equivalent to non-commercial samples by the addition of water. Tracer concentration (g Fe/ L) was measured by ICP atomic emission spectrophotometer (model 955, Thermo Jarrel Ash, Franklin, MA).…”

Section: Methodsmentioning

confidence: 99%

Tracer design for magnetic particle imaging (invited)

Ferguson

Khandhar

Krishnan

2012

Journal of Applied Physics

118

125

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Magnetic particle imaging (MPI) uses safe iron oxide nanoparticle tracers to offer fundamentally new capabilities for medical imaging, in applications as vascular imaging and ultra-sensitive cancer therapeutics. MPI is perhaps the first medical imaging platform to intrinsically exploit nanoscale material properties. MPI tracers contain magnetic nanoparticles whose tunable, size-dependent magnetic properties can be optimized by selecting a particular particle size and narrow size-distribution. In this paper we present experimental MPI measurements acquired using a homemade MPI magnetometer: a zero-dimensional MPI imaging system designed to characterize tracer performance by measuring the derivative of the time-varying tracer magnetization, M'(H(t)), at a driving frequency of 25 kHz. We show that MPI performance is optimized by selecting phase-pure magnetite tracers of a particular size and narrow size distribution; in this work, tracers with 20 nm median diameter, log-normal distribution shape parameter, r v , equal to 0.26, and hydrodynamic diameter equal to 30 nm showed the best performance. Furthermore, these optimized MPI tracers show 4 Â greater signal intensity (measured at the third harmonic) and 20% better spatial resolution compared with commercial nanoparticles developed for MRI.

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“…The sizes for which properties are altered depend upon the material and the specific property. This information was extracted from many sources including lattice constants, [24] surface energy, [25] Hall-Petch breakdown, [26] superparametric temperatures, [27] hematite-maghemite phase transition, [28] TiO 2 phases, [29] CuO, [30] and oxide film thickness on Fe. [31] .…”

Section: What Makes It Nano?mentioning

confidence: 99%

Characterization challenges for nanomaterials

Baer

Amonette

Engelhard

et al. 2008

Surface & Interface Analysis

123

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Nanostructured materials are increasingly subject to nearly every type of chemical and physical analysis possible. Due to their small sizes, there is a significant focus on tools with high spatial resolution. It is also natural to characterize nanomaterials using tools designed to analyze surfaces, because of their high surface area. Regardless of the approach, nanostructured materials present a variety of obstacles to adequate, useful, and needed analysis. Case studies of measurements on ceria and iron metal-core/oxide-shell nanoparticles are used to introduce some of the issues that frequently need to be addressed during analysis of nanostructured materials. We use a combination of tools for routine analysis including X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and x-ray diffraction (XRD) and apply several other methods as needed to obtain essential information. The examples provide an introduction to other issues and complications associated with the analysis of nanostructured materials including particle stability, probe effects, environmental effects, specimen handling, surface coating, contamination, and time.

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Nanomagnetism and spin electronics: materials, microstructure and novel properties

Cited by 208 publications

References 88 publications

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature

Tracer design for magnetic particle imaging (invited)

Characterization challenges for nanomaterials

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