Synthesis and Characterization of Magnetoelectric Nanocomposites

2009 ◽  
Vol 155 ◽  
pp. 173-188
Author(s):  
Kanhaiya Lal Yadav
Keyword(s):  
Annealing Temperature ◽  
Strong Dependence ◽  
Low Frequency ◽  
Magnetic Characteristics ◽  
Frequency Range ◽  
Field Frequency ◽  
Maximum Value ◽  
Citrate Gel Process ◽  
Small Crystallite

A simple citrate gel process was used to prepare nanocomposites of xCuFe2O4–(1−x)BiFeO3 (henceforth, CFBF) and xNi0.75Co0.25Fe2O4-(1-x)BiFeO3 (henceforth, NCFBF) with x=0.1, 0.2, 0.3 and 0.4. The phase was found to be formed at 500 °C and 700 °C for CFBF and NCFBF respectively. TEM observation showed that the average particles size is around 40 nm. The variation of the dielectric constant and the dielectric loss with frequency showed dispersion in the low frequency range. All the samples exhibit strong magnetic characteristics. The coercivity and squareness increased with the increase in annealing temperature and were maximum for samples annealed at 500°C and 700°C for CFBF and NCFBF nanocomposites, respectively, and further decrease in coercivity is attributed to decrease in aspect ratio and pinning effects in the nanocrysatllites. The ME coefficient αE showed strong dependence on HBias and maximum value of ME coefficients were 303 and 309 mV/cm Oe at magnetic field frequency of 50 kHz for CFBF and NCFBF nanocomposites respectively. The large values of ME coefficients are attributed to low coercivity, large magnetization and small crystallite size of constituent phases.

scholarly journals Electromagnetic Characterization of a Composite (RE-CB-MT) by Time Domain Spectroscopy

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Amina Bounar ◽  
Nacerdine Bouzit ◽  
Nacerdine Bourouba
Keyword(s):  
Time Domain ◽  
Ternary Mixture ◽  
Strong Dependence ◽  
Low Frequency ◽  
Theoretical Models ◽  
Dielectric Behavior ◽  
Frequency Range ◽  
Time Domain Spectroscopy ◽  
Percolation Phenomenon

The aim of this article is to study the dielectric behavior (ε, σ) in microwaves domain of composites made with Epoxy Resin (RE), Carbon Black (CB), and Magnesium Titanate (MT) on a large band of frequency. This kind of composites is very solicited for applications and miniaturization of the components circuits (cavities, antennas, substrates, etc.) in hyperfrequency electronics. In this study we have also highlighted the effect of the fillers nature and their concentrations on the behavior of these composites. The results obtained by time domain spectroscopy (TDS) have revealed the strong dependence of complex permittivity of the composite materials on both the nature and the concentration of conductive environment. Low frequency analysis (500 MHz) has been investigated to determine the conductivity of composites which is related to the percolation phenomenon. Moreover, the comparison between experimental results and theoretical models shows that the modeling Lichtenecker law is applicable to the ternary mixture in this frequency range and is in accordance with the approach postulated by Bottreau.

Thermal Annealing Dependence of High-Frequency Magnetoimpedance in Amorphous and Nanocrystalline FeSiBCuNb Ribbons

2008 ◽  
Vol 8 (6) ◽  
pp. 2873-2882 ◽  
Author(s):  
B. Hernando ◽  
V. M. Prida ◽  
M. L. Sanchez ◽  
J. Olivera ◽  
C. Garcia ◽  
...  
Keyword(s):  
High Frequency ◽  
Annealing Temperature ◽  
Driving Frequency ◽  
Network Analyzer ◽  
Frequency Range ◽  
Isothermal Heating ◽  
Amorphous Ribbons ◽  
Maximum Value ◽  
Different Temperatures ◽  
Nanocrystalline Sample

The magnetoimpedance (MI) effect in Fe73.5Si13.5B9Nb3Cu1 melt-spun amorphous ribbons has been studied in the frequency range (1–500 MHz). Isothermal heating treatments in a furnace have been employed to nanocrystallize the ribbons (1 h at 565 °C in a vacuum of 10–3 mbar), while other samples were annealed at lower temperatures (400 and 475 °C during 1 h), in order to evaluate the influence of the annealing temperature on the MI effect. The high-frequency impedance was measured using a technique based on the reflection coefficient measurements of a specific transmission line by using a network analyzer. Frequency dependence of the MI ratio, ΔZ/Z, and both resistive, ΔR/R, and reactive, ΔX/X, components of magnetoimpedance were measured in the amorphous and annealed states, at different temperatures. A maximum value of the MI ratio of about 50% at a driving frequency of 18 MHz is obtained in the nanocrystalline (annealed at 565 °C) ribbon. Maxima for R/R of about 81% at 85 MHz and ΔX/X around 140% at 5 MHz were also achieved. It is revealed that the microstructural evolution in the nanocrystalline sample leads to a magnetic softening, an optimum domain structure and a permeability which is sensitive to frequency and applied magnetic field, generating a large MI response.

Impact of Proton Irradiation on Power 4H-SiC MOSFETs

2020 ◽  
Vol 1004 ◽  
pp. 1074-1080
Author(s):  
Alexander A. Lebedev ◽  
Vitalii V. Kozlovski ◽  
Leonid Fursin ◽  
Anatoly M. Strel'chuk ◽  
Mikhail E. Levinshtein ◽  
...  
Keyword(s):  
Proton Irradiation ◽  
Removal Rate ◽  
Low Frequency ◽  
Frequency Noise ◽  
Electrical Characteristics ◽  
Low Frequency Noise ◽  
Frequency Range ◽  
Maximum Value ◽  
Noise Spectroscopy ◽  
Noise Density

Impact of 15 MeV proton irradiation on electrical characteristics and low frequency noise has been studied in high-power vertical 4H-SiC MOSFETs of 1.2 kV-class at doses 1012 £ F £ 1014 cm-2. The maximum value of the field-effect mobility µFЕ depends weakly on F up to F = 2×1013 cm-2. At F = 4×1013 cm-2, the character of the µFЕ(Vg) dependence changes radically. The maximum µFЕ decreases approximately threefold. The dose Fcr corresponding to the complete degradation of the device is about 1014 cm-2. It can be estimated as Fcr» he/n0, where he is the electron removal rate and n0 is the initial electron concentration in the drift layer. In the entire frequency range of analysis f, gate voltages, and drain-source biases, the frequency dependence of the current spectral noise density SI(f) follows the law SI ~ 1/f. From the data of noise spectroscopy, the density of traps in the gate oxide Ntv has been estimated. In non-irradiated structures, Ntv » 5.4×1018 cm-3eV-1. At Ф = 6×1013 cm-2, the Ntv value increases to Ntv » 7.2×1019cm-3eV-1. The non-monotonic behavior of the output current Id and the level of low frequency noise on dose F has been demonstrated.

Comparison of Magnetic Characteristics and Structural Properties of Commercially Available Ferritic LTCC Materials

2012 ◽  
Vol 2012 (CICMT) ◽  
pp. 000359-000364 ◽  
Author(s):  
Nelu Blaž ◽  
Andrea Marić ◽  
Goran Radosavljević ◽  
Ibrahim Atassi ◽  
Walter Smetana ◽  
...  
Keyword(s):  
Structural Properties ◽  
Low Frequency ◽  
Complex Permeability ◽  
Magnetic Characteristics ◽  
Network Analyzer ◽  
Frequency Range ◽  
Dispersion Parameters ◽  
High Frequencies ◽  
Shape Structure ◽  
Electronic Microscope

The complex permeability values are the key parameters that determine properties of ferrite components. These parameters are very dependent on material structural properties and composition. This paper presents comparison of magnetic and structural properties of commercially available LTCC materials ESL 40011 and ESL 40012. The characterization sample, for each material, is a stack of LTCC tapes forming a toroidal shape structure sintered at peak temperatures of 885 °C. For both samples, scanning with electronic microscope was performed in order to determine differences in grain size and porosity. Energy-dispersive spectroscopy (EDS) was used for the elemental analysis of the samples. Obtained EDS spectrum for each samples are compared and analyzed. Permeability, for both materials are determined in the frequency range from 10 kHz to 1 GHz. Measurement procedures are divided in two segments - for low and high frequencies. For low frequency measurements method (from 10 kHz to 1000 kHz) with discrete turns of wire is performed using LCZ meter. On higher frequency range (from 1000 kHz to 1 GHz) method with short coaxial sample holder and Vector Network Analyzer is used. Obtained characteristics for complex permeability are presented and analyzed. It was determine that ESL 40011 has lower value for complex permeability but higher frequency range than ESL 40012. LTCC material ESL 40011 have maximal value 263 for real part of complex permeability at 2.3 MHz and ESL 40012 have maximal value 678 for real part of complex permeability at 0.5 MHz. Additionally, dispersion parameters of analyzed feritic materials are determined and compared.

Study on the Mechanical Characteristics of Multilayer Piezoelectric Stack Actuator

2011 ◽  
Vol 308-310 ◽  
pp. 674-677
Author(s):  
Kai Zheng ◽  
Yi Yong Yang
Keyword(s):  
Mechanical Characteristics ◽  
Piezoelectric Materials ◽  
Strong Dependence ◽  
Dynamic Test ◽  
Low Frequency ◽  
Active Member ◽  
Phase Lag ◽  
Driving Frequency ◽  
Maximum Value ◽  
Piezoelectric Stack Actuator

This paper presents results on mechanical behavior of multilayer piezoelectric stack actuators for use in active member under combined electro-mechanical Loadings. The objective of this study is to investigate the behavior of piezoelectric materials and to determine the properties necessary for design of such actuator systems. Two types of experiments are performed: influences of the preload on characteristics of the stack and dynamic test. The measurements indicate strong dependence of the actuator piezoelectric properties on the electro-mechanical loading conditions. The displacement output is initially enhanced with an increase of the mechanical preload, and the maximum value is obtained at the preload of about 0.4 KN. But much higher preload will cause the decrease of the displacement output. Within low frequency band of about 400 Hz, the displacement magnitude of the stack is nearly constant, and the phase lag increases with the increase of the driving frequency at the applied sine sweep voltage with the amplitude of 150V.

scholarly journals In the frequency range between 1 kHz and 1 MHz

2009 ◽  
Vol 63 (3) ◽  
pp. 209-216 ◽  
Author(s):  
Vasa Radonic ◽  
Goran Radosavljevic ◽  
Nelu Blaz ◽  
Ljiljana Zivanov ◽  
Walter Smetana
Keyword(s):  
Equivalent Circuit ◽  
Loss Tangent ◽  
Complex Permittivity ◽  
Low Frequency ◽  
Small Variation ◽  
Frequency Range ◽  
Characteristic Parameters ◽  
Capacitive Method ◽  
User Friendly

In this paper, a capacitive method for characterization of LTCC tapes in the frequency range between 1kHz and 1MHz using HP 4277A LCZ meter is presented. The principle of operation using a parallel plate capacitor and equivalent circuit as a parallel connection of capacitance and a resistor is explained and characterization of test samples is measured. The fabrication process in LTCC technology and the causes that can produce the changing of characteristic parameters of substrates in fabrication are explained in detail. We indicated the importance of knowing permittivity in the function of frequency during projecting and simulating electronic components and circuits in LTCC technology. Measurements of complex permittivity, loss tangent, Q-factor based on the proposed formulas are made for LTCC tapes samples. Small variation of measured capacitance and loss tangent is obtained, approximately about 2% in whole frequency range. The value of loss tangent is approximately the same as the value specified by manufacturers. The calculated parameters for complex permittivity have bigger values then those recommended by manufacturers before firing. In the process of sintering, sheet density and microstructure of commercial tapes are changed for all used materials, causing changes of electric characteristics, especially permittivity. In the low frequency range, below 50 kHz, there is a higher variation of characteristic parameters. In this range, the parallel resistance of the equivalent circuit is on the top level of the instruments limit and these results are not reliable. A specific user-friendly program is developed which enables automatic control of measurement, recalculation of important values and processing of results.

scholarly journals Buoyancy-Free Janus Microcylinders as Mobile Microelectrode Arrays for Continuous Microfluidic Biomolecule Collection within a Wide Frequency Range: A Numerical Simulation Study

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 289 ◽  
Author(s):  
Weiyu Liu ◽  
Yukun Ren ◽  
Ye Tao ◽  
Hui Yan ◽  
Congda Xiao ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Particle Surface ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Main Body ◽  
Wide Field ◽  
Frequency Range ◽  
Field Frequency ◽  
Ac Electrokinetics ◽  
Induced Charge

We numerically study herein the AC electrokinetic motion of Janus mobile microelectrode (ME) arrays in electrolyte solution in a wide field frequency, which holds great potential for biomedical applications. A fully coupled physical model, which incorporates the fluid-structure interaction under the synergy of induced-charge electroosmotic (ICEO) slipping and interfacial Maxwell stress, is developed for this purpose. A freely suspended Janus cylinder free from buoyancy, whose main body is made of polystyrene, while half of the particle surface is coated with a thin conducting film of negligible thickness, will react actively on application of an AC signal. In the low-frequency limit, induced-charge electrophoretic (ICEP) translation occurs due to symmetric breaking in ICEO slipping, which renders the insulating end to move ahead. At higher field frequencies, a brand-new electrokinetic transport phenomenon called “ego-dielectrophoresis (e-DEP)” arises due to the action of the localized uneven field on the inhomogeneous particle dipole moment. In stark contrast with the low-frequency ICEP translation, the high-frequency e-DEP force tends to drive the asymmetric dipole moment to move in the direction of the conducting end. The bidirectional transport feature of Janus microspheres in a wide AC frequency range can be vividly interpreted as an array of ME for continuous loading of secondary bioparticles from the surrounding liquid medium along its direction-controllable path by long-range electroconvection. These results pave the way for achieving flexible and high-throughput on-chip extraction of nanoscale biological contents for subsequent on-site bioassay based upon AC electrokinetics of Janus ME arrays.

scholarly journals Characterization of the blue emission of Tm/Er co-implanted GaN

2005 ◽  
Vol 892 ◽  
Author(s):  
Iman Roqan ◽  
Carol Trager-Cowan ◽  
Ben Hourahine ◽  
Katharina Lorenz ◽  
Emilio Nogales ◽  
...  
Keyword(s):  
Room Temperature ◽  
Annealing Temperature ◽  
Strong Dependence ◽  
Blue Emission ◽  
Emission Lines ◽  
Temperature Dependent ◽  
Electron Transitions ◽  
Electron Probe Microanalyser ◽  
Pl Emission

AbstractComparative studies have been carried out on the cathodoluminescence (CL) and photoluminescence (PL) properties of GaN implanted with Tm and GaN co-implanted with Tm and a low concentration of Er. Room temperature CL spectra were acquired in an electron probe microanalyser to investigate the rare earth emission. The room temperature CL intensity exhibits a strong dependence on the annealing temperature of the implanted samples. The results of CL temperature dependence are reported for blue emission (∼ 477 nm) which is due to intra 4f-shell electron transitions (1G4 → 3H6) associated with Tm3+ ions. The 477 nm blue CL emission is enhanced strongly as the annealing temperature increases up to 1200°C. Blue PL emission has also been observed from the sample annealed at 1200°C. To our knowledge, this is the first observation of blue PL emission from Tm implanted GaN samples. Intra-4f transitions from the 1D2 level (∼ 465 nm emission lines) of Tm3+ ions in GaN have been observed in GaN:Tm films at temperatures between 20–200 K. We will discuss the temperature dependent Tm3+ emission in both GaN:Tm,Er and GaN:Tm samples.

scholarly journals Modeling and Characterization of Piezoelectric and Magnetostrictive Induced Strain Actuators

2001 ◽  
Author(s):  
Radu Pomirleanu ◽  
Victor Giurgiutiu
Keyword(s):  
Strong Dependence ◽  
Active Material ◽  
Low Frequency ◽  
Maximum Energy ◽  
Large Power ◽  
Magnetostrictive Actuators ◽  
Full Power ◽  
Magnetostrictive Actuator ◽  
Electromechanical Loading

Abstract This paper presents the results of theoretical modeling and experimental characterization of PiezoSystems Jena P-177-00 large stroke piezoelectric actuator and of Etrema AA-140J025-ES1 large stroke/large power magnetostrictive actuator. An improved smart-material actuators measurement method suited for static and low frequency actuation was devised. Analytical and finite element modeling (ANSYS) of the experimental setup to determine stiffness component characteristics was performed. The output displacements of the active material actuators were recorded in quasi-static and dynamic regimes, under varied pre-stress level, voltage and frequency values. The measurements indicated a strong dependence of the actuator stiffness and piezoelectric properties on the electromechanical loading conditions. The study also identified and calculated the parameters of the induced strain actuators electro-mechanical model. These parameters are necessary for performing design optimization to achieve maximum energy transfer and minimum power requirements. Experimentally verified data characterizing piezoelectric and magnetostrictive actuators in the full stroke/full power regime is provided.

scholarly journals Technical characterization of an 8 or 16 channel recording system to acquire electrocorticograms of mice

2017 ◽  
Vol 3 (2) ◽  
pp. 595-598
Author(s):  
Robert Englert ◽  
Fabienne Rupp ◽  
Frank Kirchhoff ◽  
Klaus Peter Koch ◽  
Michael Schweigmann
Keyword(s):  
Signal Processing ◽  
Electrical Activity ◽  
Low Frequency ◽  
Recording System ◽  
Frequency Range ◽  
Electrode Arrays ◽  
Brain Surface ◽  
The Brain

AbstractWhen performing electrocorticography, reliable recordings of bioelectrical signals are essential for signal processing and analysis. The acquisition of cellular electrical activity from the brain surface of mice requires a system that is able to record small signals within a low frequency range. This work presents a recording system with self-developed software and shows the result of a technical characterization in combination with self-developed electrode arrays to measure electrocorticograms of mice.

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