scholarly journals Electromagnetic characterization of Ni0.5Zn0.3Co0.2Fe2O4 bulk ceramics in the 1MHz-12GHz frequency range

2021 ◽  
Vol 15 (2) ◽  
pp. 136-145
Author(s):  
Vera Lucia de Brito ◽  
Julia Maria de Morais Santos ◽  
João Paulo Machado ◽  
Cristina Bormio-Nunes ◽  
Francisco Carvalho
Keyword(s):  
Complex Permittivity ◽  
Sintered Sample ◽  
Magnetic Behaviour ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Air Atmosphere ◽  
Ferrite Sample ◽  
Complex Magnetic Permeability ◽  
Permittivity Measurements

In this paper, NiZnCo ferrite was produced by solid state synthesis, calcination at 1000?C and sintering at 1250?C in air atmosphere. The microstructure and phases of the sintered sample were analysed by scanning electron microscopy and X-ray diffraction, respectively. The magnetic properties of the ferrite were evaluated by magnetization and magnetostriction measurements. The complex magnetic permeability and complex permittivity were also measured between 1MHz-12GHz and the reflection loss (RL) was calculated in the 100MHz-12GHz frequency range. The results show that the ferrite sample presents magnetostrictive behaviour and a saturation magnetization of 71 Am2/kg. Complex permittivity measurements indicate that the material has dielectric behaviour in the whole frequency range studied, with "? varying between 7-40, and magnetic behaviour in frequencies between 1MHz-5GHz. The minimum RL was found at frequencies between 2.4-3.3GHz and the calculated RL value for a thickness of 3mm was lower than ?10 dB in frequencies between 2.3-7.3GHz. These results indicate potential application as microwave absorber in the S band.

Broadband Dielectric Properties Characterization of Biological Cells

2009 ◽  
Author(s):  
Yang Yang ◽  
Rahul Mitchell Jairaj ◽  
Gaoyan Wang ◽  
Tzuen-Rong Tzeng ◽  
Xiangchun Xuan ◽  
...  
Keyword(s):  
Complex Permittivity ◽  
Biological Cells ◽  
Scattering Parameters ◽  
Frequency Range ◽  
Yeast Strains ◽  
Measurement Results ◽  
Water Measurement ◽  
Permittivity Measurements ◽  
Good Agreement

A broadband characterization method for complex permittivity measurements of biological cells is presented. An algorithm for extracting permittivity of biological cells from the measured cell suspension scattering parameters is described. A coplanar wave guide (CPW) based device is fabricated and tested. DI water measurement results show good agreement with theoretical values. Yeast cell suspensions are characterized. Complex permittivity of yeast strains is extracted over the frequency range from 30 kHz to 30 GHz.

Synthesis and Characterization of Polycrystalline Fe1.025Se Prepared Using Mechanical Alloying Followed by Powder in a Sealed Tube Method

2020 ◽  
Vol 855 ◽  
pp. 96-101
Author(s):  
Sigit Dwi Yudanto ◽  
Ryan Fitriandhani ◽  
Andika Widya Pramono ◽  
Agung Imaduddin ◽  
Budhy Kurniawan
Keyword(s):  
Raw Materials ◽  
Resistivity Measurement ◽  
Milled Powder ◽  
Sintered Sample ◽  
Atomic Ratio ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Air Atmosphere ◽  
Measurement Results

In this work, preparation of Fe1.025Se samples was done using a solid-state reaction. Iron and selenium powder were used as raw materials. The raw materials were milled using a shaker mill for 5 hours after weighed in an atomic ratio of Fe:Se=1.025:1. To find out the formation of polycrystalline Fe1.025Se, the milled powder was then compacted in a stainless-steel tube and sintered at a temperature of 355°C (for sample 1) and 745°C (for sample 2) for 6 hours. All samples were sintered in the air atmosphere and cooled rapidly in the air. XRD was used to analyze the phase formation. Based on the diffraction pattern calculation, the sintered sample at a temperature of 745°C has a higher mass fraction of the tetragonal phase than the sample sintered at 355°C. The lattice parameters of the sample sintered at a temperature of 745°C are a = 3.7688 Å and c = 5.5236 Å. According to the resistivity measurement results, it appears that the sample sintered at 745°C has a critical temperature onset of ~13.28 K.

SYNTHESIS AND CHARACTERIZATION OF ZnO NANORODS AND NANOWIRES USING PVP AS CAPPING

2009 ◽  
Vol 08 (03) ◽  
pp. 285-287 ◽  
Author(s):  
M. ESKANDARI ◽  
V. AHMADI ◽  
Sh. AHMADI
Keyword(s):  
Solution Method ◽  
Zno Nanorods ◽  
Green Emission ◽  
Zno Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Solution Method ◽  
Air Atmosphere ◽  
20 Nm

In this study, ZnO nanowires are synthesized via ZnO nanorods at low temperature by using zinc acetate dehydrate and polyvinylpyrrolidone as precursor and capping, respectively. We use chemical solution method for synthesis of ZnO nanowires. Samples are characterized by means of scanning electron microscopy and X-ray diffraction. First, the nanorods are prepared at 300°C temperature, and then they are put into the furnace under air atmosphere at 450°C for 2 h. It is observed that nanowires with 20 nm diameter are produced. Photoluminescence spectra of nanorods and nanowires are compared. It shows that intensity of ultraviolet peak in the nanowires decreases but in contrast the intensity of green emission part increases. This is because, the surface effects such as oxygen vacancies increase in the structures of ZnO .

Synthesis and Characterization of Nanostructured Mechanical Cu-Fe-Co Alloy

2018 ◽  
Vol 941 ◽  
pp. 1232-1237
Author(s):  
Alisiya Biserova-Tahchieva ◽  
Isabel López-Jiménez ◽  
Núria Llorca-Isern
Keyword(s):  
Defect Density ◽  
Nanocrystalline Structure ◽  
High Energy ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Soft Ferromagnetic ◽  
Hours Of Work ◽  
And Diffusion

Nanocrystalline structure of CuFeCo (50:25:25 wt%) alloy has been obtained by high energy mechanical milling from elemental metal powder mixture during large hours of work. Phase transformations and diffusion in the system subjected to heat treatment are discussed. Thermal stability at high temperatures is analysed and considered of importance for several applications. The nanostructure was studied by employing X-Ray diffraction and electron microscopy. It has been determined the reduction in crystallite size and the induced microstrain by the milling time. The solid solution achievement through the increment of defect density was confirmed by Mössbauer analysis. Magnetic behaviour was analysed through magnetization technique entailing their soft ferromagnetic behaviour related to the microstructural changes.

Local complex permittivity measurements of porcine skin tissue in the frequency range from 1 GHz to 15 GHz by evanescent microscopy

2009 ◽  
Vol 54 (3) ◽  
pp. 699-713 ◽  
Author(s):  
Richard A Kleismit ◽  
Gregory Kozlowski ◽  
Brent D Foy ◽  
Barbara E Hull ◽  
Marian Kazimierczuk
Keyword(s):  
Complex Permittivity ◽  
Skin Tissue ◽  
Frequency Range ◽  
Porcine Skin ◽  
Local Complex ◽  
Permittivity Measurements

Preparation and Characterization of Polycrystalline Cubic Boron Nitride (PcBN) Compacts by a Pressureless Sintering Process

2010 ◽  
Vol 105-106 ◽  
pp. 38-41 ◽  
Author(s):  
Zhen Huo Ren ◽  
Rui Zhang ◽  
Hai Long Wang ◽  
De Liang Chen ◽  
Ming Liang Li
Keyword(s):  
Boron Nitride ◽  
Cubic Boron Nitride ◽  
Cost Effective ◽  
Sintering Behavior ◽  
Pressureless Sintering ◽  
X Ray Diffraction ◽  
Polycrystalline Cubic Boron Nitride ◽  
Air Atmosphere ◽  
Sintering Method

A novel cost-effective pressureless sintering method has been developed to prepare polycrystalline cubic boron nitride (PcBN) compacts. The effect of feldspar as sintering aids was analyzed in this paper. Various amounts of feldspar from 5 to 15 wt% were added to cBN powders, and the pressureless sintering was conducted at temperatures ranging from 900°C to 1200°C under an air atmosphere. The microstructure, phase, density and microhardness of the as-obtained PcBN compacts were measured and correlated to amounts of Si added and to sintering temperatures. The sample showed superior sintering behavior in comparison to those fabricated using hot pressed sintering. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that feldspar diffused homogeneously and tightly bonded with cBN. But hBN appeared when the sintering temperature even at 900°C, which dramatically affected the property of PcBN compacts. A PcBN compact with a relative density of 91% was obtained at 1100°C and its microhardness was as high as 1000HV.

scholarly journals Characterization of nanostructured spinel NiFe2O4 obtained by soft mechanochemical synthesis

2012 ◽  
Vol 44 (3) ◽  
pp. 331-339 ◽  
Author(s):  
Z.Z. Lazarevic ◽  
C. Jovalekic ◽  
D. Sekulic ◽  
M. Slankamenac ◽  
M. Romcevic ◽  
...  
Keyword(s):  
Mechanochemical Synthesis ◽  
Nickel Ferrite ◽  
Ball Mill ◽  
Energy Dispersive Spectrometer ◽  
Sintered Sample ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures

Powdery nickel ferrite, NiFe2O4 has been obtained by soft mechanochemical synthesis in a planetary ball mill. Ni(OH)2 and Fe(OH)3 are used as initial compounds. This mixture was mechanically activated for 25h, uniaxial pressed and sintered at 1100?C for 2h. The phase composition of the sintered sample was analyzed by X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and Raman spectroscopy. Morphologies were examined by scanning electron microscopy (SEM). The electrical DC/resistivity/conductivity at different temperatures was measured using a Source Meter Keithley 2410. An Impedance/Gain-Phase Analyzer (HP-4194) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures.

scholarly journals Electromagnetic characterization of microwave sintered Sr1-xCaxMnO3 (0.0 ≤ x ≤ 0.4) thick films

2013 ◽  
Vol 7 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Rani Pawar ◽  
Ninad Velhal ◽  
Vijaya Puri
Keyword(s):  
Impedance Matching ◽  
Calcium Content ◽  
Frequency Range ◽  
Absorption Loss ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Band ◽  
Electromagnetic Characteristics ◽  
Ku Band

Electromagnetic characteristics of microwave sintered strontium calcium manganites thick film with variation in calcium content have been investigated. The X-ray diffraction analysis reveals tetragonal perovskite structure for all the compositions. The grain size increases with the increase in calcium content. The microwave absorption, complex permittivity, permeability and conductivity are reported in the frequency range of 8.2-18 GHz. The absorption loss is larger in Ku band while insertion loss is larger in X band. The permittivity, permeability and microwave conductivity decreases from X-band to Ku-band. The almost identical values of real part of permittivity and permeability indicate possible application as materials for impedance matching.

Complex Permittivity Measurements of Rainwater in the 0.5–26.5 GHz Frequency Range

2010 ◽  
Vol 7 (3) ◽  
pp. 487-490 ◽  
Author(s):  
Marzuki ◽  
Walter L. Randeu ◽  
Franz Teschl ◽  
Michael Schonhuber ◽  
Wendi Harjupa
Keyword(s):  
Complex Permittivity ◽  
Frequency Range ◽  
Permittivity Measurements

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.

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