scholarly journals Micromagnetic Simulations of Chaotic Ferromagnetic Nanofiber Networks

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 738 ◽  
Author(s):  
Tomasz Blachowicz ◽  
Christoph Döpke ◽  
Andrea Ehrmann
Keyword(s):  
Polymer Blends ◽  
Magnetization Reversal ◽  
Research Area ◽  
Diameter Distribution ◽  
Spatial Distributions ◽  
Dipolar Interactions ◽  
Micromagnetic Simulations ◽  
Small Parts ◽  
First Time

Electrospinning can be used to create nanofibers with diameters of typically a few tens to a few hundred nanometers. While pure polymers are often electrospun, it is also possible to use polymer blends or to include nanoparticles. In this way, e.g., magnetic nanofiber networks can be created with a certain diameter distribution, random fiber orientations, and random crossing positions and angles. Here we present for the first time micromagnetic simulations of small parts of stochastically oriented nanofiber networks. Magnetization reversal mechanisms are investigated for different local spatial distributions; mutual influences of neighboring magnetic fibers due to dipolar interactions are depicted. This study serves as a base for the possible use of such stochastic nanofiber networks in the research area of neuro-inspired materials.

scholarly journals Micromagnetic Simulations of Fe and Ni Nanodot Arrays Surrounded by Magnetic or Non-Magnetic Matrices

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 349
Author(s):  
Devika Sudsom ◽  
Andrea Ehrmann
Keyword(s):  
Magnetic Materials ◽  
Data Storage ◽  
Magnetization Reversal ◽  
Hysteresis Loops ◽  
Object Oriented ◽  
Basic Research ◽  
Memory Systems ◽  
The Other ◽  
Micromagnetic Simulations ◽  
Nanodot Arrays

Combining clusters of magnetic materials with a matrix of other magnetic materials is very interesting for basic research because new, possibly technologically applicable magnetic properties or magnetization reversal processes may be found. Here we report on different arrays combining iron and nickel, for example, by surrounding circular nanodots of one material with a matrix of the other or by combining iron and nickel nanodots in air. Micromagnetic simulations were performed using the OOMMF (Object Oriented MicroMagnetic Framework). Our results show that magnetization reversal processes are strongly influenced by neighboring nanodots and the magnetic matrix by which the nanodots are surrounded, respectively, which becomes macroscopically visible by several steps along the slopes of the hysteresis loops. Such material combinations allow for preparing quaternary memory systems, and are thus highly relevant for applications in data storage and processing.

scholarly journals Micromagnetic simulations of magnetization reversal of iron nanowire

2011 ◽  
Vol 266 ◽  
pp. 012022 ◽  
Author(s):  
H Xiang ◽  
D M Jiang ◽  
J C Yao ◽  
Y P Zheng ◽  
W Lu ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Micromagnetic Simulations

scholarly journals Effect of Droplet Size and Counterions on the Spatial Distribution of Ions

2019 ◽  
Author(s):  
Victor Kwan ◽  
Styliani Consta
Keyword(s):  
Spatial Distribution ◽  
Reaction Mechanisms ◽  
Charge Carriers ◽  
Transfer Reactions ◽  
Spatial Distributions ◽  
Hydronium Ions ◽  
Ionic Atmosphere ◽  
Droplet Sizes ◽  
Charge Transfer Reactions ◽  
First Time

Electrosprayed droplets have emerged as a new environment for accelerating chemical reactions by orders of magnitude relative to their bulk analogues. Nevertheless the reaction mechanisms are still unknown. Unraveling the ion spatial distribution is critical as to where charge transfer reactions are likely to take place and as to their effect on the ionic atmosphere of macroions. Here we investigate the ion spatial distributions in aqueous droplets with diameters in the range of 5 nm to 16 nm with and without counterions using molecular dynamics. The charge carriers are Na, Cl ions and model hydronium ions. For the first time droplet sizes that are accessible to experimental scrutiny are modeled atomistically. <br>

scholarly journals MESOZOIC RADIOLARIANS FROM RHYTHMICALLY LAYERED SEDIMENTS OF THE RIMSKY-KORSAKOV ISLANDS (PETER THE GREAT BAY, JAPAN SEA) AND THEIR SIGNIFICANCE FOR DETERMINING THE TRIASSIC-JURASSIC BOUNDARY

2021 ◽  
pp. 39-54
Author(s):  
O.L. Smirnova ◽  
◽  
E.A. Bessonova ◽  
T.A. Emelyanova ◽  
◽  
...  
Keyword(s):  
Peter The Great Bay ◽  
Japan Sea ◽  
Research Area ◽  
Lower Jurassic ◽  
Upper Triassic ◽  
Peter The Great ◽  
Great Bay ◽  
The Pacific ◽  
Stratigraphic Division ◽  
First Time

The results of the biostratigraphic study based on the radiolarian analysis of the rhythmically layered terrigenous deposits from the Islands of the Rimsky-Korsakov Archipelago (Peter the Great Bay, Japan Sea) have been presented. These deposits are most similar to the medium-grained turbidites. For the first time the distribution and stratigraphic division of the boundary sediments of the upper Triassic and lower Jurassic separated by a marking layer were substantiated in the research area. On the basis of comparisons with isochronous zonal units of the Pacific and Tethyan areas in the upper Triassic sediments of the studied sections, layers with Globolaxtorum tozeri (upper Rhaetian) were established, and in the lower Jurassic zone Pantanellium tanuense Zone (Hettangian) was traced and layers with Parahsuum simplum (Sinemurian – Pliensbachian) were established.

scholarly journals Ionic Liquids-Containing Silica Microcapsules: A Potential Tunable Platform for Shaping-Up Epoxy-Based Composite Materials?

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 881
Author(s):  
Ting Shi ◽  
Sébastien Livi ◽  
Jannick Duchet ◽  
Jean-François Gérard
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Diameter Distribution ◽  
Excellent Thermal Stability ◽  
Transmission Electron ◽  
Micron Size ◽  
Phosphonium Ionic Liquid ◽  
One Step ◽  
The One ◽  
First Time

In this work, silica microcapsules containing phosphonium ionic liquid (IL), denoted SiO2@IL, were successfully synthesized for the first time using the one step sol-gel method in IL/H20 emulsion. The morphologies of the obtained micron-size microcapsules, including their diameter distribution, were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal behavior of these microcapsules and the mass fraction of the encapsulated IL in the silica microcapsules were determined using thermogravimetric analysis, showing an excellent thermal stability (up to 220 °C) and highlighting that an amount of 20 wt.% of IL is contained in the silica microcapsules. In a second step, SiO2@IL microcapsules (1 wt.%) were dispersed into epoxy-amine networks to provide proof of concept of the ability of such microcapsules to act as healing agents as microcracks propagate into the epoxy networks.

Magnetic skyrmions in FePt nanoparticles having Reuleaux 3D geometry: a micromagnetic simulation study

Nanoscale ◽  
2019 ◽  
Vol 11 (42) ◽  
pp. 20102-20114 ◽  
Author(s):  
Vasileios D. Stavrou ◽  
Drosos Kourounis ◽  
Konstantinos Dimakopoulos ◽  
Ioannis Panagiotopoulos ◽  
Leonidas N. Gergidis
Keyword(s):  
Finite Element ◽  
Simulation Study ◽  
Magnetization Reversal ◽  
Magnetocrystalline Anisotropy ◽  
Micromagnetic Simulation ◽  
Fept Nanoparticles ◽  
External Fields ◽  
Micromagnetic Simulations ◽  
3D Geometry ◽  
Magnetic Skyrmions

The magnetization reversal in magnetic FePt nanoelements having Reuleaux 3D geometry is studied using Finite Element micromagnetic simulations. Multiple skyrmions are formed for a range of external fields and magnetocrystalline anisotropy values.

Submicron to Nanometer Size Single Particle Measurements

1997 ◽  
Vol 475 ◽  
Author(s):  
B. Barbara ◽  
W. Wernsdorfer ◽  
E. Bonet Orozco ◽  
K. Hasselbach ◽  
A. Benoit ◽  
...  
Keyword(s):  
Magnetization Reversal ◽  
Quantum Tunneling ◽  
Domain Walls ◽  
Switching Field ◽  
Thermally Activated ◽  
Telegraph Noise ◽  
The Mean ◽  
Macroscopic Quantum Tunneling ◽  
20 Nm ◽  
First Time

ABSTRACTLow temperature magnetization measurements of individual ferromagnetic particles and wires are presented (0.1 < T(K) < 6). The detector was a Nb micro-bridge-DC-SQUID, fabricated using electron-beam lithography. The angular dependence of the switching field could be explained approximatively by simple classical micromagnetic concepts (uniform rotation, curling…). However, dynamical measurements evidenced nucleation and propagation of domain walls, except for the smallest particles of about 20 nm. The variation of the mean switching field distribution (as a function of temperature and field sweeping rate) and of the probabilities of switching (as a function of temperature and the applied field) allowed to study in details the dynamics of magnetization reversal of individual particles. For sub-micron particles, we found that above a crossover temperature of 1K, the mean switching field and the switching probability follow a thermally activated model. For temperatures below IK, the dynamics of magnetization reversal becomes temperature independent which is interpreted in terms of deviations from the Néel-Brown model of magnetization reversal due to surface roughness and oxidazation. Although this crossovei temperature is much too large to be interpreted with current models of quantum tunneling, such an effect cannot be excluded. Measurements performed on ferromagnetic nanoparticles of good quality (single crystalline and with a diameter smaller than 25 nm), allowed us to show for the first time that the magnetization reversal can be described by thermal activation over the anisotropy energy barrier, as originally proposed by Néel. The observation of telegraph noise strengthens these results. Our measurements open the door to the observation of macroscopic quantum tunneling oí the magnetization in an individual particle containing 103-105 spins.

scholarly journals The theoretical molecular weight of NaYF4:RE upconversion nanoparticles

2017 ◽  
Author(s):  
Lewis E. Mackenzie ◽  
Jack A. Goode ◽  
Alexandre Vakurov ◽  
Padmaja P. Nampi ◽  
Sikha Saha ◽  
...  
Keyword(s):  
Molecular Weight ◽  
User Interfaces ◽  
Biomedical Applications ◽  
Crystal Phase ◽  
Diameter Distribution ◽  
Upconversion Nanoparticles ◽  
Cubic Crystal ◽  
First Time ◽  
Graphic User Interfaces ◽  
Insight Into

AbstractUpconversion nanoparticles (UCNPs) are utilized extensively for biomedical imaging, sensing, and therapeutic applications, yet the molecular weight of UCNPs has not previously been reported. We present a theory based upon the crystal structure of UCNPs to estimate the molecular weight of UCNPs: enabling insight into UCNP molecular weight for the first time. We estimate the theoretical molecular weight of various UCNPs reported in the literature, predicting that spherical NaYF4 UCNPs ~ 10 nm in diameter will be ~1 MDa (i.e. 106 g/mol), whereas UCNPs ~ 45 nm in diameter will be ~100 MDa (i.e. 108 g/mol). We also predict that hexagonal crystal phase UCNPs will be of greater molecular weight than cubic crystal phase UCNPs. Additionally we find that a Gaussian UCNP diameter distribution will correspond to a lognormal UCNP molecular weight distribution. Our approach could potentially be generalised to predict the molecular weight of other arbitrary crystalline nanoparticles: as such, we provide standalone graphic user interfaces to calculate the molecular weight both UCNPs and arbitrary crystalline nanoparticles. We expect knowledge of UCNP molecular weight to be of wide utility in biomedical applications where reporting UCNP quantity in absolute numbers or molarity will be beneficial for inter-study comparison and repeatability.

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