scholarly journals Spectroscopic analysis and temperature-dependent dielectric properties of bulk Ni–Zn ceramics

2019 ◽  
Vol 09 (02) ◽  
pp. 1950014
Author(s):  
Anand Yadav ◽  
Pankaj Choudhary ◽  
P. Saxena ◽  
V. N. Rai ◽  
A. Mishra
Keyword(s):  
Dielectric Constant ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Lattice Structure ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Temperature Dependent ◽  
Dielectric Parameters ◽  
Increase With Increase ◽  
Ion Substitution

In the present work, series of Zn ion-doped Ni[Formula: see text]ZnxFe2O4 ([Formula: see text]) ceramics were prepared by the double sintered solid-state reaction route to find out the influence of Zn[Formula: see text] ions on the crystal structure, lattice structure and dielectric behavior of parent NiFe2O4. X-ray diffraction (XRD) study favors that all the prepared compounds belong to the cubic spinel structure. Lattice parameters found to have increasing value with increased Zn[Formula: see text] ion substitution. The Raman scattering measurement discerns optical-active modes with blue shift as the doping increases. The dielectric constant ([Formula: see text] and dielectric tangent loss (tan [Formula: see text] decrease with an increase in frequency and at higher frequency, both become constant. Dielectric parameters observe nonlinear behavior with increasing Zn[Formula: see text] ion substitution. Room temperature dielectric constant of 10% Zn ion-doped NiFe2O4 [Ni[Formula: see text]Zn[Formula: see text]Fe2O4] is much higher as compared to other prepared ceramics. The room temperature ac conductivity is found to increase with increase in frequency and temperature-dependent ac conductivity increases with increase in temperature.

EFFECT OF Ni DOPING ON STRUCTURAL AND DIELECTRIC PROPERTIES OF GdFeO3

2013 ◽  
Vol 22 ◽  
pp. 179-183 ◽  
Author(s):  
PAWANPREET KAUR ◽  
K. K. SHARMA ◽  
RAVI KUMAR ◽  
RABIA PANDIT
Keyword(s):  
Dielectric Constant ◽  
Ac Conductivity ◽  
Tangent Loss ◽  
X Ray Diffraction ◽  
Ni Doping ◽  
Reaction Route ◽  
Lattice Contraction ◽  
X Ray ◽  
Ion Substitution ◽  
Tan Δ

The polycrystalline samples of GdFe 1-x Ni x O 3(x=0.0, 0.1) are prepared by solid state reaction route, their structure is analyzed by powder X-ray diffraction (XRD) and Rietveld refinement. We are also studying the behavior of dielectric constant (ε′), tangent loss (tan δ) as a function of frequency from 75 kHz to 5 MHz and AC conductivity (σac) from 75 kHz to 1 MHz for both the compositions at room temperature. It is noticed that Ni 3+ ion substitution results in lattice contraction and enhancement in dielectric constant, tangent loss and AC conductivity.

Atomistic prediction on the configuration- and temperature-dependent dielectric constant of Be0.25Mg0.75O superlattice as a high-κ dielectric layer

2021 ◽  
Author(s):  
Gyuseung Han ◽  
In Won Yeu ◽  
Kun Hee Ye ◽  
Seung-Cheol Lee ◽  
Cheol Seong Hwang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dft Calculations ◽  
Bond Length ◽  
Dielectric Layer ◽  
Room Temperature ◽  
High Dielectric Constant ◽  
Temperature Dependent ◽  
High Dielectric

Through DFT calculations, a Be0.25Mg0.75O superlattice having long apical Be–O bond length is proposed to have a high bandgap (>7.3 eV) and high dielectric constant (∼18) at room temperature and above.

Influence of Ca-Doping on Structural, Magnetic and Dielectric Properties of Ba3Co2-xCaxFe24O41 Hexaferrite Powders

2015 ◽  
Vol 241 ◽  
pp. 226-236 ◽  
Author(s):  
Neha Solanki ◽  
Rajshree B. Jotania
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sol Gel ◽  
Calcium Content ◽  
Combustion Method ◽  
Dielectric Behavior ◽  
Dielectric Parameters ◽  
Ca Doping ◽  
Auto Combustion ◽  
Magnetic And Dielectric Properties

Influence of Ca substitution on structural, magnetic and dielectric properties of Ba3Co2-xCaxFe24O41(where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0), prepared by Sol-Gel auto-combustion method, has been investigated in present studies. The obtained powder was sintered at 950 oC for 4 hrs. in the static air atmosphere. Structural analysis of Ca-doped Ba3Co2-xCaxFe24O41powders revealed pure Z-type hexaferrite phase at low temperature. The frequency dependent dielectric constant (Єʹ) and magnetic properties such as remanent magnetization (Mr), saturation magnetization (Ms) and coercivity (Hc) were studied. It is observed that coercivity increased gradually with increase in calcium content. The real dielectric constant (Єʹ) and dielectric loss tangent (tan δ) were studied in the frequency range of 20Hz to 2MHz. The dielectric parameters for all samples show normal dielectric behavior as observed in hexaferrites. Contents of Paper

ON THE DIELECTRIC BEHAVIOR OF LiCo3/5Fe2/5VO4 CERAMICS

2010 ◽  
Vol 24 (07) ◽  
pp. 665-670
Author(s):  
MOTI RAM
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Frequency Dependence ◽  
Chemical Method ◽  
Arrhenius Plot ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
Low Frequencies ◽  
Different Temperatures ◽  
Tan Δ

The LiCo 3/5 Fe 2/5 VO 4 ceramics has been fabricated by solution-based chemical method. Frequency dependence of the dielectric constant (εr) at different temperatures exhibits a dispersive behavior at low frequencies. Temperature dependence of εr at different frequencies indicates the dielectric anomalies in εr at Tc (transition temperature) = 190°C, 223°C, 263°C and 283°C with (εr) max ~ 5370, 1976, 690 and 429 for 1, 10, 50 and 100 kHz, respectively. Frequency dependence of tangent loss ( tan δ) at different temperatures indicates the presence of dielectric relaxation in the material. The value of activation energy estimated from the Arrhenius plot of log (τd) with 103/T is ~(0.396 ± 0.012) eV.

scholarly journals Dielectric Properties of the System GdCo1-xFexO3Synthesized by Chemical Route (x = 0.10, 0.20)

2006 ◽  
Vol 3 (4) ◽  
pp. 313-328
Author(s):  
K. D. Mandal ◽  
L. Behera
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Dielectric Constant ◽  
Chemical Method ◽  
Perovskite Oxides ◽  
Space Charge Polarization ◽  
Dielectric Behavior ◽  
Dielectric Parameters ◽  
Chemical Route ◽  
Scanning Electron

The perovskite oxides GdCo1-xFexO3(x = 0.10, 0.20) were prepared by chemical method. The dielectric behavior of compositions with x = 0.10 and 0.20 in the system GdCo1-xFexO3was studied in the temperature range 300-500 K. It is observed that dielectric constant increases with increasing Fe2+ions concentration. The frequency dependence of dielectric constant in these materials indicates that space charge polarization contributes significantly to their observed dielectric parameters. A uniform distribution of grains is observed from the microstructure by Scanning electron microscopy.

scholarly journals Frequency and Temperature Dependent Dielectric Response of Fe3O4 Nano-crytallites

2014 ◽  
Vol 6 (3) ◽  
pp. 399-406 ◽  
Author(s):  
M. Z. Ansar ◽  
S. Atiq ◽  
K. Alamgir ◽  
S. Nadeem
Keyword(s):  
Magnetite Nanoparticles ◽  
Sol Gel ◽  
Dielectric Behavior ◽  
Tangent Loss ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Dielectric Tangent Loss ◽  
Auto Combustion ◽  
Combustion Technique

Magnetite nanoparticles have been prepared by using sol-gel auto combustion technique. The samples are prepared by using different concentrations of fuel. Structural characterization has been done using X-Ray diffraction technique and it was observed that fuel concentration can affect the structural properties of Magnetite nanoparticles. The dielectric properties for all the samples such as dielectric constant (??), dielectric tangent loss (tan ?) and dielectric loss factor (??) have been studied as a function of frequency and temperature in the range 10 Hz–20 MHz  and it was found that these nanoparticles can be used in microwave devices because of their good dielectric behavior. © 2014 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v6i3.17938 J. Sci. Res. 6 (3), 399-406 (2014)

Dielectric and ac Conductivity Studies on Nanocrystalline Mn Modified Cobalt Ferrite

2018 ◽  
Vol 24 (8) ◽  
pp. 5629-5632 ◽  
Author(s):  
Sweety Supriya ◽  
Sunil Kumar ◽  
Manoranjan Kar
Keyword(s):  
Dielectric Constant ◽  
Frequency Response ◽  
Electrical Transport ◽  
Ac Conductivity ◽  
Cobalt Ferrite ◽  
Electrical Transport Properties ◽  
Arrhenius Behavior ◽  
Temperature Dependent ◽  
Two Layer Model ◽  
Frequency Temperature

The ac conductivity and dielectric properties on CoFe2−xMnxO4 for x = 0.00, 0.10, 0.15 and 0.20 have been studied in detail. All the samples were prepared in nanocrystalline size. These materials are found to be crystallized to Fd <mml:math display="block"> <mml:semantics> <mml:mover accent="true"> <mml:mi>3</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:semantics> </mml:math> m space group in cubic spinel structure. The dielectric constant and ac conductivity has been discussed as a function of frequency, temperature and composition. The relation between dielectric constant and ac conductivity has been analyzed and the results validate each other. The frequency response of ac conductivity (σac) obeys Johnschers power law and the parameters obtained, explain the sources of ac and dc electrical conductivity in the material. The frequency response of σac follows Maxwell–Wagner two-layer model. The influence of frequency as pumping force on activation energy has been determined. The temperature dependent ac conductivity shows the Arrhenius behavior. The σac observed to be enhanced with increase in frequency as well as temperature. The semiconducting behavior (NTCR) was also evident from temperature dependent electrical transport properties study. The low value of ac conductivity suggests a possible use of this material in dielectric applications.

Dielectric Properties of β-SiAlON at High Temperature Using Perturbation Method

2008 ◽  
Vol 403 ◽  
pp. 121-123 ◽  
Author(s):  
Young Hoon Seong ◽  
Ha Neul Kim ◽  
Do Kyung Kim
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Dielectric Properties ◽  
Perturbation Method ◽  
Hot Pressing ◽  
Room Temperature ◽  
Tangent Loss ◽  
Resonator Method

-SiAlON with various z-values (z = 0.5~4.0) were produced by hot pressing. The dielectric properties (dielectric constant and tangent loss) of -SiAlON were characterized by the post-resonator method at room temperature and by the perturbation method from room temperature to 1200 oC at 2.45 GHz, respectively. Effect of z-values and temperatures with -SiAlON were investigated.

AC conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses

2019 ◽  
Vol 60 (6) ◽  
pp. 222-230
Author(s):  
Deepika Deepika ◽  
Hukum Singh
Keyword(s):  
Dielectric Relaxation ◽  
Ac Conductivity ◽  
Lower Energy ◽  
Dielectric Relaxation Time ◽  
Frequency Exponent ◽  
Dielectric Parameters ◽  
Cbh Model ◽  
Increase With Increase ◽  
Different Temperatures ◽  
Frequency Temperature

The present paper reports the ac conductivity and dielectric relaxation of Se80−xTe20Bix (x=6, 12) glasses at various temperatures and frequencies. It was found that ac conductivity increases on increase of frequency, temperature as well as Bi content. The increase in conductivity is due to the formation of lower energy Se–Bi and Te–Bi bonds which takes the system to a stable lower energy configuration. The values of frequency exponent (s) were calculated and it was found that samples obey CBH model of conduction. Density of states (N(Ef)) near the fermi level were calculated at different temperatures and it was found that addition of Bi increases the number of localised states in the tails which leads to increase in ac conductivity. Further, it was found that dielectric parameters increase with increase in temperature. However, a decrease in both dielectric constant (ε′) and dielectric loss ((ε″) was observed with increase in frequency. Beside this, dielectric relaxation time (τ) and activation energy of relaxation (∆Eτ) were also determined for both the samples under study and was found to be lower for Se68Te20Bi12 glass.

Electrical Property of Transparent Thin Films TiO2 and Sr-Doped TiO2 Developed by Spin Coating

2013 ◽  
Vol 665 ◽  
pp. 263-266
Author(s):  
M.H. Mangrola ◽  
A.S. Pillai ◽  
B.H. Parmar ◽  
V.G. Joshi
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Property ◽  
Spin Coating ◽  
Glass Substrate ◽  
High Frequency ◽  
Ac Conductivity ◽  
Room Temperature ◽  
Coating Technique ◽  
Increase With Increase

Transparent thin film of pure TiO2and 3% Sr-doped TiO2(Ti0.97Sr0.03O2) were prepared by spin coating technique onto well-cleaned glass substrate. The dielectric behaviour of the films were studied at room temperature for different frequencies. The capacitance of both films were is found to decrease with increasing frequency and at higher frequencies capacitance becomes constant. AC conductivity is found to continuously increase with increase in the frequency. At high frequency it doesnt show any change and remains almost constant.

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