scholarly journals Reconfigurable Surface Micropatterns Based on the Magnetic Field-Induced Shape Memory Effect in Magnetoactive Elastomers

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4422
Author(s):  
Matija Lovšin ◽  
Dominik Brandl ◽  
Gašper Glavan ◽  
Inna A. Belyaeva ◽  
Luka Cmok ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Diffraction Efficiency ◽  
Optical Elements ◽  
Plasticity Effect ◽  
Simple Theoretical Model ◽  
Reflection Configuration ◽  
Moderate Magnetic Field ◽  
Micrometer Scale ◽  
The Magnetic Field ◽  
Magnetoactive Elastomer

A surface relief grating with a period of 30 µm is embossed onto the surface of magnetoactive elastomer (MAE) samples in the presence of a moderate magnetic field of about 180 mT. The grating, which is represented as a set of parallel stripes with two different amplitude reflectivity coefficients, is detected via diffraction of a laser beam in the reflection configuration. Due to the magnetic-field-induced plasticity effect, the grating persists on the MAE surface for at least 90 h if the magnetic field remains present. When the magnetic field is removed, the diffraction efficiency vanishes in a few minutes. The described effect is much more pronounced in MAE samples with larger content of iron filler (80 wt%) than in the samples with lower content of iron filler (70 wt%). A simple theoretical model is proposed to describe the observed dependence of the diffraction efficiency on the applied magnetic field. Possible applications of MAEs as magnetically reconfigurable diffractive optical elements are discussed. It is proposed that the described experimental method can be used as a convenient tool for investigations of the dynamics of magnetically induced plasticity of MAEs on the micrometer scale.

scholarly journals Feasibility of Probing the Filler Restructuring in Magnetoactive Elastomers by Ultra-Small-Angle Neutron Scattering

2021 ◽  
Vol 11 (10) ◽  
pp. 4470
Author(s):  
Inna A. Belyaeva ◽  
Jürgen Klepp ◽  
Hartmut Lemmel ◽  
Mikhail Shamonin
Keyword(s):  
Magnetic Field ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Iron Particles ◽  
Filler Particles ◽  
The Magnetic Field ◽  
Magnetoactive Elastomer

Ultra-small-angle neutron scattering (USANS) experiments are reported on isotropic magnetoactive elastomer (MAE) samples with different concentrations of micrometer-sized iron particles in the presence of an in-plane magnetic field up to 350 mT. The effect of the magnetic field on the scattering curves is observed in the scattering vector range between 2.5 × 10−5 and 1.85 × 10−4 Å−1. It is found that the neutron scattering depends on the magnetization history (hysteresis). The relation of the observed changes to the magnetic-field-induced restructuring of the filler particles is discussed. The perspectives of employing USANS for investigations of the internal microstructure and its changes in magnetic field are considered.

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

Fragmentation of a Filamentary Cloud Threaded by Perpendicular Magnetic Field

2018 ◽  
Vol 14 (A30) ◽  
pp. 105-105
Author(s):  
Tomoyuki Hanawa ◽  
Takahiro Kudoh ◽  
Kohji Tomisaka
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Outer Boundary ◽  
Radial Distance ◽  
Radial Density ◽  
Radial Density Distribution ◽  
Model Cloud ◽  
Moderate Magnetic Field ◽  
Self Gravity ◽  
The Magnetic Field

AbstractFilamentary molecular clouds are thought to fragment to form clumps and cores. However, the fragmentation may be suppressed by magnetic force if the magnetic fields run perpendicularly to the cloud axis. We evaluate the effect using a simple model. Our model cloud is assumed to have a Plummer like radial density distribution, $\rho = {\rho _{\rm{c}}}{\left[ {1 + {r^2}/(2p{H^2})} \right]^{2p}}$ , where r and H denote the radial distance from the cloud axis and the scale length, respectively. The symbols, ρc and p denote the density on the axis and radial density index, respectively. The initial magnetic field is assumed to be uniform and perpendicular to the cloud axis. The model cloud is assumed to be supported against the self gravity by gas pressure and turbulence. We have obtained the growth rate of the fragmentation instability as a function of the wavelength, according to the method of Hanawa, Kudoh & Tomisaka (2017). The instability depends crucially on the outer boundary. If the displacement vanishes in regions very far from the cloud axis, cloud fragmentation is suppressed by a moderate magnetic field. If the displacement is constant along the magnetic field in regions very far from the cloud, the cloud is unstable even when the magnetic field is infinitely strong. The wavelength of the most unstable mode is longer for smaller index, p.

scholarly journals Низкоэнергетическое состояние электронного пучка в коаксиальном диоде с однородным анодом и неоднородным профилем магнитного поля

2018 ◽  
Vol 44 (20) ◽  
pp. 102
Author(s):  
А.В. Громов ◽  
М.Б. Гойхман ◽  
Н.Ф. Ковалев ◽  
А.В. Палицин ◽  
M.I. Fuks ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Energy State ◽  
Field Configuration ◽  
Low Energy ◽  
Moderate Magnetic Field ◽  
First Time ◽  
Cylindrical Anode ◽  
The Magnetic Field ◽  
Reflection Plane

AbstractThe possible formation of an extended low-energy state of electron beam in a coaxial diode with homogeneous cylindrical anode and moderate magnetic field with inhomogeneous profile is demonstrated for the first time. It is established that, depending on the magnetic field configuration, virtual cathodes (VCs) of two types can be formed: (i) a stationary VC with a localized reflection plane and (ii) a moving VC with a two-stream low-energy state of the electron beam.

MAGNETIC FIELD ORIENTATION DEPENDENCE OF THE MICROWAVE RESPONSE IN YBa2Cu3O7-δ

2003 ◽  
Vol 17 (04n06) ◽  
pp. 929-935
Author(s):  
E. SILVA ◽  
R. MARCON ◽  
R. FASTAMPA ◽  
M. GIURA ◽  
S. SARTI
Keyword(s):  
Magnetic Field ◽  
Vortex Motion ◽  
Field Measurements ◽  
Orientation Dependence ◽  
Field Orientation ◽  
Quasiparticle Density ◽  
Conventional Models ◽  
Moderate Magnetic Field ◽  
The Magnetic Field ◽  
Microwave Resistivity

We present microwave resistivity measurements at 21 GHz in YBa 2 Cu 3 O 7-δ thin film as a function of the temperature and the magnetic field. Measurements are taken in various relative orientations of the microwave current, dc magnetic field and c axis. Attention is focussed on measurements taken with the dc field parallel to the (a, b) planes. In moderate magnetic field, we show that the microwave magnetic response is made up of a vortex motion contribution, which can be described by conventional models, and a noticeable magnetic field induced increase of the quasiparticle density, which exhibits features typical of the existence of lines of nodes in the superconducting gap. We estimate the effective vortex viscosity for vortex motion across the (a, b) planes.

MR FLUIDS WITH NANO-SIZED MAGNETIC PARTICLES

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3167-3172 ◽  
Author(s):  
Cl. Kormann ◽  
H.M. Laun ◽  
H.J. Richter
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Elevated Temperatures ◽  
Shear Rates ◽  
Mr Fluids ◽  
High Shear Rates ◽  
Moderate Magnetic Field ◽  
Actuator Design ◽  
The Magnetic Field

Recently magnetorheological fluids with nanosized magnetic ferrite particles have become available. Their composition, rheological and magnetic properties are described. A comparison with conventional MR fluids based on micron-sized particles is given. The yield stress of nano-MR fluids can be increased by a moderate magnetic field (0,2 T) by 4000 Pa. It can be modulated by the magnetic field with a response time of less than 5 ms. Details are given on the long term thermal stability at 150 °C, on flow properties at elevated temperatures and at high shear rates. Design principles for MR fluid actuator design are outlined.

MAGNETIC FIELD INDUCED NEAR-BAND-GAP OPTICAL PROPERTIES IN EuTe LAYERS

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2999-3003 ◽  
Author(s):  
F. G. G. HERNANDEZ ◽  
A. B. HENRIQUES ◽  
P. H. O. RAPPL ◽  
E. ABRAMOF
Keyword(s):  
Magnetic Field ◽  
Optical Properties ◽  
Band Gap ◽  
Stokes Shift ◽  
Red Shift ◽  
Near Band Edge ◽  
Zero Field ◽  
Excitation Light ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The magnetic response of the near-band-edge optical properties is studied in EuTe layers. In several magneto-optical experiments, the absorption and emission are described as well as the related Stokes shift. Specifically, we present the first experimental report of the photoluminescence excitation (PLE) spectrum in Faraday configuration. The PLE spectra shows to be related with the absorption spectra through the observation of resonance between the excitation light and the zero-field band-gap. A new emission line appears at 1.6 eV at a moderate magnetic field in the photoluminescence (PL) spectra. Furthermore, we examine the absorption and PL red-shift induced by the magnetic field in the light of the d - f exchange interaction energy involved in these processes. Whereas the absorption red-shift shows a quadratic dependence on the field, the PL red-shift shows a linear dependence which is explained by spin relaxation of the excited state.

scholarly journals Testing the magnetoactive elastomer sample for compression with the test machine

2021 ◽  
Vol 2094 (4) ◽  
pp. 042064
Author(s):  
Andrey Minaev
Keyword(s):  
Magnetic Field ◽  
Testing Machine ◽  
Compression Modulus ◽  
Test Machine ◽  
Self Healing ◽  
Compression Force ◽  
Linear And Nonlinear ◽  
The Magnetic Field ◽  
Nonlinear Nature ◽  
Magnetoactive Elastomer

Abstract A sample of a magnetoactive silicone composite with ferromagnetic fillers is examined on a testing machine. The dependences of the change in the values of the moduli of longitudinal elasticity on deformation are plotted for various modes of compression of the sample. The characteristics of the linear and nonlinear dynamics of changes in the moduli of longitudinal elasticity are given as a function of the magnitudes of the deformations of the material during compression. Within the limits of deformation of the sample, which is 24% of its height, the moduli of longitudinal elasticity are linear. The nonlinear nature of the change in the compression modulus occurs when the sample is deformed over 40%. When the compression ratio of the sample was up to 72%, the compression modulus increased by a factor of 9 without the action of a magnetic field and by a factor of 22 under the action of a magnetic field. The influence of the magnetic field on the growth of the compression moduli with the increase in the compression force ranges is shown. The property of the material to self-healing (“shape memory”) was established after testing in the mode of maximum compression of ultimate loads.

scholarly journals Magnetoelectric Response of Laminated Cantilevers Comprising a Magnetoactive Elastomer and a Piezoelectric Polymer, in Pulsed Uniform Magnetic Fields

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6390
Author(s):  
Gašper Glavan ◽  
Inna A. Belyaeva ◽  
Kevin Ruwisch ◽  
Joachim Wollschläger ◽  
Mikhail Shamonin
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Voltage Response ◽  
Peak Voltage ◽  
Magnetic Field Sensors ◽  
Voltage Coefficient ◽  
Piezoelectric Polymer ◽  
Laminated Structures ◽  
The Magnetic Field ◽  
Magnetoactive Elastomer

The voltage response to pulsed uniform magnetic fields and the accompanying bending deformations of laminated cantilever structures are investigated experimentally in detail. The structures comprise a magnetoactive elastomer (MAE) slab and a commercially available piezoelectric polymer multilayer. The magnetic field is applied vertically and the laminated structures are customarily fixed in the horizontal plane or, alternatively, slightly tilted upwards or downwards. Six different MAE compositions incorporating three concentrations of carbonyl iron particles (70 wt%, 75 wt% and 80 wt%) and two elastomer matrices of different stiffness are used. The dependences of the generated voltage and the cantilever’s deflection on the composition of the MAE layer and its thickness are obtained. The appearance of the voltage between the electrodes of a piezoelectric material upon application of a magnetic field is considered as a manifestation of the direct magnetoelectric (ME) effect in a composite laminated structure. The ME voltage response increases with the increasing total quantity of the soft-magnetic filler in the MAE layer. The relationship between the generated voltage and the cantilever’s deflection is established. The highest observed peak voltage around 5.5 V is about 8.5-fold higher than previously reported values. The quasi-static ME voltage coefficient for this type of ME heterostructures is about 50 V/A in the magnetic field of ≈100 kA/m, obtained for the first time. The results could be useful for the development of magnetic field sensors and energy harvesting devices relying on these novel polymer composites.

scholarly journals Effects of High Magnetic Field Postannealing on Microstructure and Properties of Pulse Electrodeposited Co-Ni-P Films

2016 ◽  
Vol 2016 ◽  
pp. 1-6
Author(s):  
Donggang Li ◽  
Chun Wu ◽  
Qiang Wang ◽  
Jean-Paul Chopart ◽  
Jicheng He ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Structure And Properties ◽  
Microstructure And Properties ◽  
Field Annealing ◽  
Fcc Phase ◽  
Moderate Magnetic Field ◽  
The Right ◽  
Deposited Film ◽  
The Magnetic Field

The influence of high magnetic field annealing on the morphology, microstructure, and properties of pulsed-electrodeposited Co-Ni-P films was investigated. The as-deposited film with a rough surface changed into uniform nanocrystalline during the magnetic field annealing process. In particular, the formation of intestine-like appearance with spherical clusters vanishing is favored from a moderate magnetic field strength of 6 T, due to the polarized effects. Meantime, the diffraction peak (111) of α (fcc) phase shifts to the right direction, which is attributed to the fact that more Co atoms from phosphide phase are incorporated into the Ni lattice, in comparison with the case of annealing under 0 T and 12 T magnetic fields. The mechanical and magnetic properties of the films reach relative optimum values at B=6 T. The evolution of magneto-induced modification in the Co-Ni-P morphology, structure, and properties can be explained by the polarized effect and the diffusion-acceleration effect under a high magnetic field.

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