scholarly journals Effect of Ca-substitution on the Magnetic and Dielectric Properties of Mn-Zn Ferrites

2012 ◽  
Vol 4 (2) ◽  
pp. 297 ◽  
Author(s):  
M. M. Rahman ◽  
P. K. Halder ◽  
F. Ahmed ◽  
T. Hossain ◽  
M. Rahaman
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Sintering Temperature ◽  
Initial Permeability ◽  
Q Factor ◽  
Dielectric Polarization ◽  
Ca Substitution ◽  
Magnetic And Dielectric Properties ◽  
Curie Temperature Tc

Spinel Mn-Zn ferrites with composition MnxZn0.4Ca0.6-2xFe2+xO4, where x = 0.10, 0.15, 0.20, 0.25 and 0.30 have been prepared by conventional ceramic technique sintered at    1300 °C for 4 hours. The influence of Ca-substitution on various properties of Mn-Zn ferrites have been studied in this work. Investigations were carried out by the measurements of Curie temperature, permeability, loss tangent, Q-factor, dielectric constant and AC resistivity of the samples. Curie temperature (Tc), the real part of initial permeability (µ´), loss tangent (tan ?), and AC resistivity have been found to be decreased while the Q-factor increases with the increase in Ca-content. The frequency characteristics of the dielectric constant and AC resistivity have been found to be decreased as the frequency increases. Maxwell-Wagner interfacial type of dielectric polarization was observed with the addition of Ca-content over the entire range of frequency considered. Keywords: Spinel ferrites; Sintering temperature; Initial permeability; Dielectric constant.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.9752 J. Sci. Res. 4 (2), 297-306 (2012)

Preparation and electrical properties of Ni–Cu–Zn system doped with the magnesium oxide

2014 ◽  
Vol 28 (23) ◽  
pp. 1450157 ◽  
Author(s):  
O. M. Hemeda ◽  
A. Tawfik ◽  
D. M. Hemeda ◽  
A. M. Elsheekh
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Lattice Parameter ◽  
Initial Permeability ◽  
Spectra Analysis ◽  
Cationic Distribution ◽  
Tan Δ

A sery of ferrite samples, Ni 0.1 Cu 0.2 Mg x Zn 0.7-x Fe 2 O 4, (x = 0.00, 0.15, 0.25, 0.35, 0.45, 0.55 and 0.70) have been prepared by the standard ceramic techniques, sintered at 1200°C for 2 h, and their crystalline structures were investigated by using X-ray diffraction, which confirmed the formation of Ni 0.1 Cu 0.2 Mg x Zn 0.7-x Fe 2 O 4 phase. The presence of Mg content increases the crystallinity of the given ferrite which is considered as catalyst for the accomplishment of the solid state reaction. The lattice parameter and crystallite size were calculated from XRD. The cationic distribution was estimated from the theoretical values of lattice parameters. The IR spectra analysis has been studied. The dielectric constant for the ferrite system Ni – Cu – Zn gradually increases with temperature up to nearly Curie temperature and then increase sharply beyond the Tc. The Curie temperature obtained from the [Formula: see text] versus T is in agreement with the Curie temperature obtained from other measurements. Dielectric loss tangent ( tan δ) has the same behavior as dielectric constant [Formula: see text]. A minimum value of dielectric loss tangent ( tan δ) for the system " Ni – Cu – Zn " was observed at x = 0.45. Magnetic permeability has been studied. The dependence of initial permeability on temperature exhibit a peak which is called Hopkinson peak (HP) in the vicinity of Curie temperature and confirmed the phase purity of ferrite sample. The increasing of porosity and decreasing of grain size play an important role in decreasing μi. It is clear that the value of Tc is found to increase by increasing the concentration of diamagnetic substitution Mg for " Ni – Cu – Zn " system.

Synthesis and Characteristics of MgO Coated BST-Mg2TiO4 Composite Ceramics

2012 ◽  
Vol 512-515 ◽  
pp. 1180-1183
Author(s):  
Qian Qian Jia ◽  
Hui Ming Ji ◽  
Shan Liu ◽  
Xiao Lei Li ◽  
Zheng Guo Jin
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Loss Tangent ◽  
Phase Shifters ◽  
Precipitation Method ◽  
Composite Ceramics ◽  
Low Dielectric ◽  
Dielectric Constant And Loss ◽  
Bst Ceramics

The (Ba, Sr)TiO3 (hereafter BST) ceramics are promising candidate for applying in tunable devices. MgO coated BST-Mg2TiO4 (BSTM-MT) composite ceramics were prepared to obtain the low dielectric constant, low dielectric loss, good dielectric constant temperature stability, and high tunability of BST ceramics. The Ba0.55Sr0.40Ca0.05TiO3 nanoparticles were coated with MgO using the precipitation method and then mixed with Mg2TiO4 powders to fabricate BSTM-MT composite ceramics. The morphologies, phases, elements, and dielectric properties of the sintered ceramics were investigated. The core-shell structure of BST powder wrapped with MgO was clearly observed from the TEM image. After sintered at 1100 °C for 2 h, the composite ceramics expressed dense microstructures from SEM images and two main phases BST and Mg2TiO4 were detected in the XRD patterns. The dielectric constant and loss tangent were both reduced after the coating. The reduced dielectric constant and loss tangent of BSTM-MT were 190, 0.0011 (2MHz), respectively. The ceramics exhibited the diffuse phase transition near the Curie temperature and the Curie temperature shifted from 10 °C to 5 °C after the coating. Since the continuous Ti-O bonds were disconnected with the MgO coating, the tunability was reduced to 15.14 % under a DC bias field of 1.1 kV/mm. The optimistic dielectric properties made it useful for the application of tunable capacitors and phase shifters.

scholarly journals Effects Of Cd On Physical And Some Magnetic Properties Of Co-Cd Ferrites

1970 ◽  
Vol 35 (2) ◽  
pp. 229-235 ◽  
Author(s):  
Saroaut Noor ◽  
SS Sikder ◽  
M Samir Ullah ◽  
MA Hakim ◽  
Shireen Akhter
Keyword(s):  
Curie Temperature ◽  
Lattice Parameter ◽  
Initial Permeability ◽  
X Ray Diffraction ◽  
Ceramic Method ◽  
X Ray ◽  
Cobalt Ferrites ◽  
Vegard’S Law ◽  
Ray Density ◽  
Curie Temperature Tc

Polycrystalline samples of Cd substituted cobalt ferrites with composition Co1-xCdxFe2O4 (x = 0.0- 0.6 in steps of 0.1) were prepared by double sintering ceramic method. The samples were sintered at 1050°C for 3 hours. X-ray diffraction pattern of the samples showed single phase cubic spinel structure. It was found that the lattice parameter increases linearly with increasing Cd content following Vegard’s law. The apparent density and X-ray density exhibited similar behavior. The Curie temperature Tc has been determined from the temperature dependence of permeability. It was found that the Curie temperature continuously decreased with increasing Cd content and is attributed to the weakening of JAB exchange interaction. The initial permeability, μ' increases with increasing Cd content up to x = 0.6 and then decreases. Key words: Co-Cd ferrite; Lattice parameter; Permeability DOI: http://dx.doi.org/10.3329/jbas.v35i2.9429 JBAS 2011; 35(2): 229-235

scholarly journals 5G planar branch line coupler design based on the analysis of dielectric constant, loss tangent and quality factor at high frequency

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Nor Azimah Mohd Shukor ◽  
Norhudah Seman
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Quality Factor ◽  
Loss Tangent ◽  
High Frequency ◽  
Q Factor ◽  
Bandwidth Enhancement ◽  
Branch Line ◽  
Fifth Generation ◽  
Quality Factor Q

Abstract This study focuses on the effect of different dielectric properties in the design of 3-dB planar branch line coupler (BLC) using RT5880, RO4350, TMM4 and RT6010, particularly at high frequency of 26 GHz, the fifth generation (5G) operating frequency. The analysis conducted in this study is based on the dielectric constant, loss tangent and quality factor (Q-factor) associated with the dielectric properties of the substrate materials. Accordingly, the substrate that displayed the best performance for high frequency application had the lowest dielectric constant, lowest loss tangent and highest Q-factor (i.e., RT5880), and it was chosen to enhance our proposed 3-dB BLC. This enhanced 3-dB BLC was designed with the inclusion of microstrip-slot stub impedance at each port for bandwidth enhancement, and the proposed prototype had dimensions of 29.9 mm × 19.9 mm. The design and analysis of the proposed 3-dB BLC were accomplished by employing CST Microwave Studio. The performance of scattering parameters and the phase difference of the proposed BLC were then assessed and verified through laboratory measurement.

scholarly journals Microstructure and magnetic properties of soft nickel ferrite

2015 ◽  
Vol 39 (1) ◽  
pp. 59-64 ◽  
Author(s):  
Mahabub Alam Bhuiyan ◽  
Sheikh Manjura Hoque ◽  
Shamima Choudhury
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Curie Temperature ◽  
Sintering Temperature ◽  
Great Influence ◽  
Complex Permeability ◽  
Scanning Electron Micrographs ◽  
Academy Of Sciences ◽  
Curie Temperature Tc ◽  
Microstructure And Magnetic Properties

Polycrystalline NiFe2O4 samples were prepared from analytical grade powder of NiO and Fe2O3 by conventional double sintering technique. The samples were sintered at 1000 - 1400°C. The scanning electron micrographs (magnification ´ 10000) of the samples revealed that the grain size increases and the porosity decreases with the increase in sintering temperature. These changes in microstructure, grain size and porosity with sintering temperature have great influence on the magnetic properties of NiFe2O4. Complex permeability (u’) over the frequency range from 1 kHz to 13 MHz for the samples at different sintering temperatures (1000-1400°C) has been observed. Variation of permeability with the applied temperature has been observed at various sintering temperature from which Curie temperature have been calculated. Decreased value of Curie temperature (Tc) has been found with the increase of sintering temperature.Journal of Bangladesh Academy of Sciences, Vol. 39, No. 1, 59-64, 2015

scholarly journals Composition, Temperature and Frequency Dependent Magnetic, Dielectric and Electrical Properties of Magnesium-Zinc Ferrites

2012 ◽  
Vol 36 (2) ◽  
pp. 199-212 ◽  
Author(s):  
M Mahbubur Rahman ◽  
Md Shahin Sheak ◽  
Soheli Pervin ◽  
Nasir Uddin ◽  
Farid Ahmed ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Curie Temperature ◽  
Interfacial Polarization ◽  
Initial Permeability ◽  
Dielectric Behavior ◽  
Dielectric Dispersion ◽  
Cu Content ◽  
Virgin State ◽  
Academy Of Sciences ◽  
Magnetic Dielectric

Polycrystalline spinel MgxZn0.3Cu0.7-2xFe2+xO4, where x = 0.10, 0.20, 0.25, 0.30 and 0.35  ferrites (hereafter abbreviated as Mg-Zn) have been prepared by conventional double sintering technique. The samples were sintered at 1250°C in air for 6 hours. Measurements have been done at temperature and frequency ranges of 0 - 350°C and 0 - 500 kHz, respectively. In this work, some extrinsic magnetic properties such as Curie temperature, initial permeability, loss factor, quality factor, dielectric constant and resistivity of the samples have been studied. The Curie temperature and loss tangent of the samples decreased with increase in Cu-content whereas permeability, Qfactor, resistivity and dielectric constant have been noticed to be increased with the increase in Cucontent.  The decrease in Curie temperature related to fact of weakening the strength of exchange AB  interaction. Maxwell-Wagner type of interfacial polarization might have found correlated with  the normal dielectric behavior of the samples, however no relaxation peaks were observed in the  dielectric dispersion curves of the Mg-Zn samples in virgin state or doped state. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12963 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 199-212, 2012

Effect of Li2O-Al2O3-Bi2O3-SiO2 Glass on Electromagnetic Properties of Ni0.16Cu0.22Zn0.62Fe2O4-BaTiO3 Composites at Low Sintering Temperature

2019 ◽  
Vol 960 ◽  
pp. 250-255
Author(s):  
Qiang Zhao ◽  
Huai Wu Zhang ◽  
Jie Li
Keyword(s):  
Dielectric Constant ◽  
Saturation Magnetization ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Glass Content ◽  
Electromagnetic Properties ◽  
Magnetic And Dielectric Properties ◽  
Tan Δ ◽  
Quality Factor Q ◽  
Doping Ratio

In the present work, the composite material Ni0.16Cu0.22Zn0.62Fe2O4-BaTiO3 (NCZF-BTO, in a 10:1) was synthesized with different additive amounts of Li2O-Al2O3-Bi2O3-SiO2 (LABS) glass using a traditional solid-state reaction method and sintered at 900 °C. The synthesized composites were then comparatively investigated; in addition to their phases and density, their magnetic and dielectric properties, which include the saturation magnetization(4πMs), coercivity (Hc), permeability (μ'), quality factor (Q), dielectric constant (ε')and dielectric loss (tan δ) were characterized. In contrast to the undoped composites, the performance of the LABS-doped samples were enhanced. The optimal performance was obtained when the LABS glass content reached 1.0wt%. At this level of doping, the bulk density increased from 4.883 g/cm3 to 5.021g/cm3, the saturation magnetization (4πMs) increased from 3819.5 to 4113.6Gs, the coercivity (Hc) decreased from 111 to 106.5A/m, the permeability (μ') at 10 MHz increased from 25.8 to 61.1, and the dielectric constant (ε') at 10 MHz increased from 18.9 to 23.4. On further increasing the LABS glass content to1.5 wt%, the performance of the composite generally deteriorated, except for the dielectric constant,which increased to 27.1. In short, the optimal LABS glass doping ratio was determined to be 1.0 wt%.

Spark Plasma Sintered AlN-BN Composites and its Dielectric Properties

2008 ◽  
Vol 368-372 ◽  
pp. 940-942
Author(s):  
Hai Yang Zhao ◽  
Wei Min Wang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Loss Tangent ◽  
Dielectric Loss Tangent ◽  
Sintering Temperature ◽  
Hexagonal Boron Nitride ◽  
Relative Dielectric Constant ◽  
Ceramic Composites ◽  
Spark Plasma

A series of samples of hexagonal boron nitride-aluminum nitride (10-90, 15-85, 20-80, 25-75, 30-70wt.%) ceramic composites were prepared by spark plasma sintering in a nitrogen atmosphere at 1650 °C-1800 °C for 5min. Different amounts of CaF2 were added as sintering aids. The effects of CaF2 and sintering temperature on densification and dielectric properties were discussed. The addition of CaF2 enhances relative dielectric constant and loss tangent of the samples. The increase in sintering temperature promotes the densification and decreases the dielectric loss tangent. When being sintered at 1700 °C, the relative density, dielectric constant and dielectric loss tangent of the sample with 15wt.%BN are 98.04%, 7.15 and 6.31×10-4 respectively.

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