scholarly journals Frequency and temperature dependent transport properties of NiCuZn ceramic oxide

2015 ◽  
Vol 33 (2) ◽  
pp. 259-267 ◽  
Author(s):  
M. Belal Hossen ◽  
A.K.M. Akther Hossain
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Polycrystalline Sample ◽  
Phenomenological Theory ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
Complex Dielectric Constant ◽  
Ceramic Oxide ◽  
Frequency Independent

AbstractA polycrystalline sample of ceramic oxide Ni0.27Cu0.10Zn0.63Fe2O4 was prepared by the solid state reaction method. The sintered sample was well polished to remove any oxide layer formed during sintering and the two surfaces of the pellet were coated with a silver paste as a contact material. Among dielectric properties, complex dielectric constant (ε* = εʹ - jεʺ), loss tangent (tanδ) and ac conductivity (σac) in the frequency range of 20 Hz to 2 MHz were analyzed in the temperature range of 303 to 498 K using a Wayne Kerr impedance analyzer (model No. 6500B). The experimental results indicate that ε, εʺ, tanδ and σac decrease with an increase in frequency and increase with increasing temperature. The transition temperature, as obtained from dispersion curve of εʹ, shifts towards higher temperature with an increase in frequency. The variation of dielectric properties with frequency and temperature shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop’s phenomenological theory. The frequency dependent conductivity results satisfy the Jonscher’s power law, σT(ω) = σ(o)+Aωn, and the results show the occurrence of two types of conduction process at elevated temperature: (i) low frequency conductivity, due to long-range ordering (frequency independent, region I), (ii) mid frequency conductivity at the grain boundaries (region II, dispersion) and (iii) high frequency conductivity at the grain interior due to the short-range hopping mechanism (frequency independent plateau, region III).

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

scholarly journals Influence of Erbium Doping on Dielectric Properties of Zinc Borotellurite Glass System

2016 ◽  
Vol 846 ◽  
pp. 161-171 ◽  
Author(s):  
Siti Shafinas Zulkefly ◽  
Halimah Mohamed Kamari ◽  
Muhammad Nor Azlan Abdul Azis ◽  
Wan Mohd Daud Wan Yusoff
Keyword(s):  
Dielectric Properties ◽  
Molar Volume ◽  
Structural Changes ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Xrd Analysis ◽  
Glass System ◽  
Response Measurement ◽  
Xrd Pattern ◽  
Higher Temperature

Glasses of the system {[ (TeO2)70 (B2O3)30]70 (ZnO)30}100-y (Er2O3)y containing different concentration of Er2O3 (ranging from 0 to 5 mol %) was prepared from melt-quenching technique. The structural changes were studied by XRD analysis and FTIR analysis. The XRD pattern shows the glasses are amorphous. The higher concentration of Er2O3, the more unit of TeO3 would transform to TeO4 and formation of B-O vibrational groups. The density and molar volume was obtained attribute to non-bridging oxygen (NBO) and are found the density and molar volume of the glass system are increasing. The densities range from 3630 kg/m3 to 3960 kg/m3. The dielectric constant ε’ and dielectric loss factor ε’’ which were characterized in the frequency range 10-2 – 106 Hz over temperature range 50°C – 200 °C, show a larger value at lower frequency and higher temperature (above 110°C ). The results of dielectric response measurement show that interfacial polarization at low frequency, and orientation polarization at intermediate and high frequency.Keywords: Dielectric properties; Activation Energy; Rare Earth; Polarization; Non-Bridging Oxygen;

DIELECTRIC PROPERTIES OF DRY, GEOLOGIC MATERIALS

Geophysics ◽  
1970 ◽  
Vol 35 (4) ◽  
pp. 624-645 ◽  
Author(s):  
M. Saint‐Amant ◽  
David W. Strangway
Keyword(s):  
Dielectric Properties ◽  
Loss Tangent ◽  
Relaxation Times ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Relaxation Peak ◽  
Debye Relaxation ◽  
Thermally Activated ◽  
Geologic Materials ◽  
Frequency Independent

A detailed investigation of the dielectric properties of powdered and solid dry rocks in the frequency range of 50 hz to 2 mhz has revealed the following general characteristics: 1) All dry rocks, powdered and solid, show an increase in both the dielectric constant and the loss tangent as frequency decreases and as temperature increases. This dispersion is believed to be due to polarization associated with charge buildup at grain boundaries or at grain imperfections. 2) Dry powdered rocks often show a thermally‐activated relaxation peak with a typical Debye‐relaxation character. This is due to the presence of pyroxene and biotite and may be associated with other minerals. The relaxation peak is not seen in solid rocks, where it is hidden by the low‐frequency dispersion. 3) At high frequencies, the loss tangent approaches a constant value which is frequency independent. This behavior is observed in many dielectrics and may be the result of a distribution of relaxation times.

Dielectric Properties of A, B-Site Mn-Doped LaTiO3+δ

2018 ◽  
Vol 921 ◽  
pp. 78-84
Author(s):  
Yan Chen ◽  
Qi Qi Yan ◽  
Yi Min Cui
Keyword(s):  
Dielectric Properties ◽  
Dielectric Response ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Conventional Solid State Reaction ◽  
Dielectric Characteristics ◽  
Low Dielectric ◽  
A Site ◽  
Mn Doped

A-site Mn-doped La1-xMnxTiO3+δand B-site doped LaMnxTi1-xO3+δ(x = 0.1, 0.2) composites were synthesized by conventional solid-state reaction method. The low-frequency complex dielectric properties of the composites were investigated as functions of temperature (77 K ≤ T ≤ 360 K) and frequency (100 Hz ≤ f ≤ 1 MHz), respectively. The dielectric constants of A-site doped samples are higher than that of B-site doped samples. The loss tangents of the low doped samples are much less than that of the high doped samples. The A-site doped composites exhibit intrinsic dielectric response with a dielectric constant of ~40 in the temperature below 250 K. Interestingly, the dielectric constants of B-site doped composites always increased in the temperature range from 77 to 360 K. And it is clearly observed that extraordinarily low dielectric loss tangents appear in LaMn0.1Ti0.9O3+δ, which are much lower than that of LaMn0.2Ti0.8O3+δ. These changes indicate that the doped content can affect the intrinsic dielectric characteristics significantly.

scholarly journals L attice V ibrational C haracteristics , Crystal Structure s , and D ielectric P roperties of Li Mn PO 4  Microwave Dielectric Ceramics as a Function of Sintering Temperature

2021 ◽  
Author(s):  
xiangyu wang ◽  
encai xiao ◽  
Lingcui Zhang ◽  
Yue Xu ◽  
tong liu ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Low Frequency ◽  
Solid State Reaction Method ◽  
Packing Fraction ◽  
Raman Shift ◽  
Microwave Dielectric Ceramics ◽  
Structure Property ◽  
Microwave Dielectric ◽  
Dielectric Ceramics

Abstract LiMnPO4 (LMP) microwave dielectric ceramics were manufactured at different temperatures via a standard solid-state reaction method, and the LMP ceramic sintered at 750 °C displayed dielectric properties of εr = 7.82, Q × f = 29,189 (f = 12.7 GHz). The lattice vibrational characteristics of LMP ceramics were studied utilizing both infrared reflection and Raman scattering spectroscopy to clarify the basic principle of the dielectric response. The intrinsic properties that were fitted and simulated based on the infrared spectra agreed with the measured property values. The low-frequency vibrational modes contributed more to the dielectric properties than the high-frequency modes. Upon increasing the temperature, the permittivity was positively correlated with the bond length but showed the opposite trend of the Raman shift of mode 9 Ag(υ1). The Q × f value was positively correlated with the packing fraction but negatively correlated with the FWHM of mode 10 Ag(υ3). Thus, the structure-property relationships of LMP ceramics were established as a function of sintering temperature.

scholarly journals Ionic Transportation and Dielectric Properties of YF3:Eu3+ Nanocrystals

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 995 ◽  
Author(s):  
Xiaoyan Cui ◽  
Tingjing Hu ◽  
Jingshu Wang ◽  
Junkai Zhang ◽  
Xin Zhong ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Dielectric Properties ◽  
Carrier Transport ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Structural Disorder ◽  
Ion Diffusion ◽  
Ion Migration ◽  
Conductivity Increase ◽  
The Difference

The ionic transportation and dielectric properties of YF3:Eu3+ nanocrystals are investigated by AC impedance spectroscopy. The ion diffusion coefficient and conductivity increase along with the doping concentration and reach their highest values at 4% of Eu3+. The difference of ionic radius between Eu3+ and Y3+ leads to the structural disorder and lattice strain, which deduces the increase of the ion diffusion coefficient and conductivity before 4% Eu3+ doping; then the interaction of the neighboring doping ions is dominated, which results in the difficulty of ion migration and decreases of the ion diffusion coefficient and conductivity. The strong dispersion of the permittivity in the low frequency region indicates that the charge carrier transport mechanism is the ion hopping in the system. The low-frequency hopping dispersion is affected by an interfacial polarization, which exhibits a Maxwell-Wagner relaxation process, and its loss peak shifts to higher frequency with the ionic conductivity increasing.

Dielectric Relaxation and Microwave Dielectric Properties of Bi2O3–ZnO–Ta2O5 Ceramics

2002 ◽  
Vol 17 (6) ◽  
pp. 1502-1506 ◽  
Author(s):  
Hyuk-Joon Youn ◽  
Clive Randall ◽  
Ang Chen ◽  
Tom Shrout ◽  
Michael T. Lanagan
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Low Frequency ◽  
Microwave Dielectric Properties ◽  
Β Phase ◽  
Microwave Dielectric ◽  
Α Phase ◽  
Frequency Independent ◽  
Temperature Relaxation ◽  
Two Phases

The permittivity of two primary phases within the Bi2O3–ZnO–Ta2O5 system was measured from 100 Hz to approximately 8.7 GHz. A cubic pyrochlore (Bi3/2Zn1/2)(Zn1/2Ta3/2)O7 phase (a phase) exhibited a dielectric constant of 71 at low frequency which decreased to 64 at approximately 10 GHz. A lower symmetry zirconolite Bi2(Zn1/3Ta2/3)2O7 phase (β phase) was also measured and had a frequency independent dielectric constant of 60. The temperature dependence of the capacitance (τC), measured from −55 to 120 °C, was 78 ppm/°C for the β phase and nonlinear for the α phase having no unique slope. The primary difference in dielectric properties between these two phases was a low-temperature relaxation of the α phase, which is modeled as a basic Debye-type relaxation.

Impedance and dielectric properties of mercury cuprate at nonsuperconducting state

2015 ◽  
Vol 29 (29) ◽  
pp. 1550205 ◽  
Author(s):  
Z. Güven Özdemir ◽  
Ö. Aslan Çataltepe ◽  
Ü. Onbaşlı
Keyword(s):  
Dielectric Properties ◽  
Low Frequency ◽  
Interfacial Polarization ◽  
Nyquist Plot ◽  
Dielectric Constants ◽  
Frequency Interval ◽  
Radio Waves ◽  
Spectroscopy Analysis ◽  
High Dielectric ◽  
First Time

In this paper, impedance and dielectric properties of nonsuperconducting state of the mercury-based cuprate have been investigated by impedance measurements within the frequency interval of 10 Hz–10 MHz for the first time. The dielectric loss factor [Formula: see text] and ac conductivity [Formula: see text] parameters have also been calculated for non-superconducting state. According to impedance spectroscopy analysis, the equivalent circuit of the mercury cuprate system manifests itself as a semicircle in the Nyquist plot that corresponds to parallel connected resistance–capacitance circuit. The oscillation frequency of the circuit has been determined as approximately 45 kHz which coincides with the low frequency radio waves. Moreover, it has been revealed that the mercury-based cuprate investigated has high dielectric constants and hence it may be utilized in microelectronic industry such as capacitors, memory devices etc., at room temperature. In addition, negative capacitance (NC) effect has been observed for the mercury cuprate regardless of the operating temperatures at nonsuperconducting state. Referring to dispersions in dielectric properties, the main contribution to dielectric response of the system has been suggested as dipolar and interfacial polarization mechanisms.

EFFECT OF SINTERING TEMPERATURE ON THE STRUCTURAL AND DIELECTRIC PROPERTIES OF ZINC CADMIUM FERRITES PREPARED BY EGG-WHITE TECHNIQUE

2010 ◽  
Vol 24 (17) ◽  
pp. 1907-1914 ◽  
Author(s):  
M. ABDULLAH DAR ◽  
W. A. SIDDIQUI ◽  
M. ALAM
Keyword(s):  
Dielectric Properties ◽  
Sintering Temperature ◽  
Interfacial Polarization ◽  
Phenomenological Theory ◽  
Egg White ◽  
Frequency Range ◽  
Wagner Model ◽  
Maximum Value ◽  
Zinc Cadmium ◽  
Tan Δ

The effect of cadmium substitution and sintering temperature on the microstructure and dielectric properties of nano ZnCd x Fe 2-x O 4 ferrites (x=0.0, 0.05, 0.1, 0.2, 0.3 and 0.5) has been investigated and prepared by egg-white technique. Electrical conductivity and dielectric measurements have been analysed in the frequency range from 100 Hz to 10 MHz. The variation of the real (ε′) and imaginary (ε″) part of dielectric constant, AC conductivity (σ AC ) and loss tangent ( tan δ) with frequency has been studied. It follows the Maxwell–Wagner model based on the interfacial polarization in consonance with the Koop's phenomenological theory. It is found that the permittivity of ZnCd x Fe 2-x O 4 ferrites improved and shows a maximum value (~9 × 103) at 100 Hz for the x=0.1 sample.

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