Effect of Sintering Temperature on Dielectric Properties of CaCu3Ti4O12 Ceramics Prepared by Mechanochemical Process

2014 ◽  
Vol 974 ◽  
pp. 157-161
Author(s):  
Masturah Mohamed ◽  
Mahesh Talari ◽  
Mohd Salleh Mohd Deni ◽  
Azlan Zakaria
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Sintering Temperature ◽  
Processing Conditions ◽  
Dielectric Measurements ◽  
Frequency Range ◽  
Grain Sizes ◽  
Barrier Capacitance ◽  
Different Temperatures ◽  
Increasing Temperature

CaCu3Ti4O12(CCTO) is well known to have colossal dielectric constant in the range of 105.It is widely accepted that this phenomenon may be attributed to internal layer barrier capacitance (IBLC) model. The dielectric properties of CCTO were reported to be strongly dependent on the processing conditions and grain size. In this work, CCTO samples with different grain sizes were produced by varying sintering temperature in order to investigate IBLC effect on dielectric properties of CCTO. The samples were sintered at four different temperatures, (T=1100°C, 1050°C, 1000°C and 950°C). Dielectric measurements were carried out for the samples in the frequency range of 102– 106Hz using impedance spectrometer. Electron micrographs showed that increasing temperature promoted the grain growth of CCTO while sintering. The internal crystalline defects are seen to play major role by increasing the grain conductivity in dipole formation and increased the dielectric constant of the samples.

Effect of Y2O3 on the Sintering, Mechanical and Dielectric Properties of Mullite/h-BN Composites

2016 ◽  
Vol 848 ◽  
pp. 28-31
Author(s):  
Han Jin ◽  
Yong Feng Li ◽  
Zhong Qi Shi ◽  
Hong Yan Xia ◽  
Guan Jun Qiao
Keyword(s):  
Fracture Toughness ◽  
Dielectric Constant ◽  
Phase Composition ◽  
High Temperature ◽  
Dielectric Properties ◽  
Liquid Phase ◽  
Flexural Strength ◽  
Sintering Temperature ◽  
Pressureless Sintering ◽  
Different Temperatures

Mullite/10 wt. %h-BN composites with 5 wt. % Y2O3 additive were fabricated by pressureless sintering at different temperatures. The densification, phase composition, microstructure, mechanical and dielectric properties of the mullite/h-BN composites were investigated. With the addition of Y2O3, the sintering temperature of the mullite/h-BN composites declined, while the density, mechanical and dielectric properties all increased. The addition of Y2O3 promoted the formation of liquid phase at high temperature, which accelerated the densification. Besides, Y2O3 particles which were located at the grain boundaries inhibited the grain growth of mullite matrix. For the mullite/h-BN composites with Y2O3 additive, the appropriate sintering temperature was about 1600°C. The relative density, flexural strength, fracture toughness and dielectric constant of the Y2O3 doped mullite/h-BN composite sintered at 1600 °C reached 82%, 135 MPa, 2.3 MPa·m1/2 and 4.9, respectively.

scholarly journals Dielectric and Conductivity Properties of Some Wood Composites

2016 ◽  
Vol 8 ◽  
pp. 51-60
Author(s):  
K.Ch. Varada Rajulu ◽  
B.N. Mohanty
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Low Temperature ◽  
Temperature Region ◽  
Loss Factor ◽  
Wood Composites ◽  
Frequency Range ◽  
Increasing Temperature ◽  
Coaxial Probe

This study presents the dielectric and conductivity properties as function of temperature and frequency of wood based composites. These properties were measured by an open-ended coaxial probe at frequency range between 100 kHz to 100MHz, temperature from 30OC to 200OC which is fully computer interfaced. It has been observed that dielectric constant (ε') and dielectric loss factor (ε") increase with increasing temperature and decrease with increasing frequency. At low temperature region, the conductivity depends significantly on the frequency. However, with the increase in temperature dielectric relaxation takes place and the dependency of the conductivity on frequency get reduced. The patterns of variation were established for the studied specimens and discrepancies were discussed. The study of dielectric properties will help in improving the drying, heating and gluing processes of wood and wood based products.

Solid State Sintering and Microstructural Evolution on Wide Frequency Range Dielectric Responses of Mechanically Activated CaTiO3 Ceramics

2015 ◽  
Vol 1107 ◽  
pp. 38-44
Author(s):  
Wong Yick Jeng ◽  
Hassan Jumiah ◽  
Mansor Hashim
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sintering Temperature ◽  
Microstructural Analysis ◽  
High Energy ◽  
Wide Frequency Range ◽  
Milling Process ◽  
Frequency Range ◽  
Wide Range

The CaTiO3samples were prepared by high-energy ball milling process followed by sintering process from 1040 to 1200°C. X-ray diffraction (XRD), microstructural analysis, and dielectric properties over a wide range of frequency varying from 0.01 Hz to 1 GHz at room temperature were investigated. The formation of a single phase CaTiO3with orthorhombic structure was achieved at 1120°C and above. From a morphological point of view, sintering temperature promoted grain growth. Dielectric properties in the frequency range 0.01 Hz - 1 MHz revealed a relaxation-type process. Interfacial phenomena were the possible physical mechanisms that gave rise to these relaxation-type plots. Extending the frequencies above ~1 MHz yielded a frequency-independent characteristic of dielectric constant (ε'). These turned out to the relatively small dielectric loss (tan δ) values. The origin of the dielectric responses in the frequency range 1 MHz - 1 GHz was attributed to the domination of dipolar polarization. The grain size effect in sintered CaTiO3samples was prominent, notably in dielectric responses above ~1 MHz. Increase in sintering temperature remarkably led to an enhancement in dielectric constant values and reduction in dielectric loss values. Therefore, a significant correlation existed between microstructural features and dielectric properties.

Characterization and dielectric properties of sodium fluoride doped talc

Clay Minerals ◽  
2014 ◽  
Vol 49 (4) ◽  
pp. 551-558
Author(s):  
S. Gümüştas ◽  
K. Köseoğlu ◽  
E. E. Yalçinkaya ◽  
M. Balcan
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Firing Temperature ◽  
Room Temperature ◽  
Dielectric Measurements ◽  
Frequency Range ◽  
Detailed Characterization ◽  
Circuit Element

AbstractThe purpose of this paper is to determine the effect of NaF and firing temperature on the dielectric properties (dielectric constant and dielectric loss) of talc, which is used in the electrical and electronic industries as a circuit element. A detailed characterization of the samples was made by XRD, FTIR, SEM and TG-DTG methods. Dielectric measurements were performed in the frequency range from 1 MHz to 80 MHz at room temperature. The dielectric constant value increased with an increase in firing temperature due to the removal of polarizable compounds from the talc structure. The higher dielectric constant values were obtained by addition of NaF. The dielectric loss of NaF doped talc decreased with the increase of firing temperature and increased with the increase of the amount of NaF.

Dielectric Properties of Na2O Doped Cao-B2O3-SiO2 System Glass-Ceramics

2013 ◽  
Vol 750-752 ◽  
pp. 492-496
Author(s):  
Peng Fei Wei
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sintering Temperature ◽  
Glass Ceramics ◽  
Wide Frequency Range ◽  
Microwave Properties ◽  
Low Dielectric Constant ◽  
Frequency Range ◽  
Low Dielectric

The behavior of dielectric and microwave properties against sintering temperature was been carried out on CaO-B2O3-SiO2glass-ceramics with Na2O addition by XRD and SEM. The results show that 0.5 wt.% Na2O addition is advantageous to improve the dielectric and microwave properties due to increasing the major crystalline CaSiO3. With further increasing Na2O content, α-SiO2is the predominant crystalline phase instead of CaSiO3. The CBS glass-ceramics with 0.5 wt.% Na2O sintered at 875°C has a bulk density of 2.51g·cm-3, and which possesses good dielectric properties:εr=6.2,tanδ=1.9×10-3(10 MHz) and low dielectric constant below 2×10-3over a wide frequency range. The proposed dielectrics can find applications in microwave devices, which require low dielectric loss and low dielectric constant.

Sintering and Dielectric Properties of SrTiO3-based Ceramics

2012 ◽  
Vol 1397 ◽  
Author(s):  
Juan Li ◽  
Dengren Jin ◽  
Lixin Zhou ◽  
Jinrong Cheng
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Precursor Solution ◽  
Particle Sizes ◽  
Low Dielectric ◽  
Different Temperatures ◽  
High Dielectric ◽  
Room Temperature Dielectric Constant

ABSTRACTHigh dielectric tunability, low dielectric loss tangent and appropriate level of dielectric constant are the basic requirements for applications as electrically tunable dielectric microwave devices. In our experiments, the SrTiO3 green compacts made of the powder mixtures with various particle sizes were infiltrated with a BaTiO3 precursor solution and sintered at different temperatures between 1280 and 1350 ºC for 2 hours and 1350 ºC for 6 hours. The sintering, microstructural and dielectric properties were investigated. Results showed that the relative density of SrTiO3 ceramics could reached 93% when sintered at 1280 ºC for 2 hours. When sintered for 6 hours at 1350 °C, the room temperature dielectric constant of SrTiO3 reaches 900 at a frequency of 1MHz. It has only weak temperature dependence between 100 and 500K. The reason of the low sintering temperature for the dense SrTiO3 ceramics and the effects of sintering scheme on the dielectric properties from 100 K to 500 K are discussed in this paper.

Effect of Sintering Temperatures on Sr-Doped NiO Ceramics

2016 ◽  
Vol 840 ◽  
pp. 61-65 ◽  
Author(s):  
Nurul Nadia Mohd Salim ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Dielectric Constant ◽  
Grain Size ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Size Range ◽  
Sintering Temperature ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Solid State Method ◽  
State Method

Sr - doped NiO ceramic was prepared using solid state method. The calcination temperature used at 950 oC for 4 hours and the sintering temperatures was varied from 1100 to 1300 oC for 3 hours. The results depict the microstructures increasing in grains size (1-8 μm) by increase of sintering temperatures. The density and porosity testing support the result of microstructures analysis. The larger grains size induced the increase in density and lower in porosity. The dielectric properties is observed in a wide frequency range of (1 - 1 000 MHz). The increase of dielectric constant is associated with the decrease of dielectric loss. The optimum sintering temperature was obtained at 1200 oC depict the grain size range (1 - 2 μm) with highest dielectric constant (1.61 x 103) and lowest dielectric loss (1.15) at 1MHz.

Study the Effect of Heat Treatment and Pressure on some the Optical Properties of the Pure PVA Nano Polymer

2021 ◽  
Vol 900 ◽  
pp. 16-25
Author(s):  
Tabarak Mohammed Awad ◽  
May A.S. Mohammed
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Refractive Index ◽  
Optical Properties ◽  
Absorption Coefficient ◽  
Polyvinyl Alcohol ◽  
Complex Dielectric Constant ◽  
Different Temperatures ◽  
German Origin ◽  
Increasing Temperature

In this study, some optical properties were studied of the pure vinyl polyvinyl alcohol (PVA) nanopolymer (German origin). Under the influence of different temperatures and pressures of PVA. Where 25 samples were prepared for the purpose of conducting the research. Which studied the study of these samples was done by recording the absorbance and transmittance spectra of the wavelengths (200-900) nm. From them, absorbance, transmittance, reflectivity, absorption coefficient, refractive index, extinction coefficient, complex dielectric constant were calculated. At different temperatures (25,40, 80, 120, 160)°C. And with different pressures within the range (7.5,8,8.5,9,9.5) MPa. The results are that the permeability of the polymer (PVA) at different temperatures for each pressure decreases with increasing temperature, and that all other calculated optical properties increase with increasing temperature.

scholarly journals The effects of calcination and doping on structural and dielectric properties of CaCu3-xCoxTi4O12 ceramic

2019 ◽  
Vol 8 (3) ◽  
pp. 234
Author(s):  
Nasr Hadi ◽  
Tajdine Lamcharfi ◽  
Farid Abdi ◽  
Nor-Said Echtoui ◽  
Ahmed Harrach ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Complex Impedance ◽  
Impedance Analysis ◽  
Xrd Analysis ◽  
Secondary Phases ◽  
Solid State Method ◽  
Complex Impedance Analysis ◽  
Oxide Powders ◽  
Increasing Temperature

<p class="Abstract"><span lang="EN-US">The influences of calcination temperature and doping with cobalt in A–site on structural and dielectric properties of CaCu<sub>3-x</sub>Co<sub>x</sub>Ti<sub>4</sub>O<sub>12</sub> (CCCxTO, x = 0.00, 0.02 and 0.10) ceramics sintered at 1050 <sup>0</sup>C for 8h were investigated. The ceramic samples are prepared by the conventional solid-state method using high purity oxide powders, and they are calcined at 850 °C, 950 °C and 1050 <sup>0</sup>C for 4h. The X-ray diffraction (XRD) analysis of pure and doped CCTO samples calcined at 950 °C and 1050 <sup>0</sup>C showed no traces of any other secondary phases, while impurity phases alongside CCTO phase in the x=0.00 sample calcined at 850 <sup>0</sup>C was observed. Scanning electron microscopy (SEM) investigation showed an increase in grain size with increasing of Co content and calcining temperature. Dielectric measurements indicated that the dielectric constant of the pure CCTO calcined at 1050 <sup>0</sup>C/4h has a low value in the frequency range of 1kHz up to 1MHz, whereas the substitution of Co up to x = 0.10 into CCTO caused a huge increase in the dielectric constant value of the calcined samples which is equal to 153419 and 18957 at 950 <sup>°</sup>C and 1050 <sup>0</sup>C respectively. The complex impedance analysis of all samples shows a decrease in resistance with an increasing temperature, which suggests a semiconductor nature of the samples.</span></p>

Effect of moisture content on dielectric properties of banana leaves and peels in frequency range of 1–20 GHz

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Soumya Sundar Pattanayak ◽  
Soumen Biswas
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Measurement Data ◽  
Banana Peel ◽  
Frequency Range ◽  
Proposed Model ◽  
Banana Leaves ◽  
Banana Leaf

Abstract The quality of agricultural products can be remotely sensed and enhanced by determining the dielectric properties. This paper studies the dielectric properties of banana leaf and banana peel over the frequency range 1–20 GHz using the open-ended coaxial probe (OCP) method. A new curve fitting model is proposed to characterize the dielectric properties of banana leaf and banana peel. The different moisture content (MC) levels are considered for both banana leaf and banana peel samples and, their dielectric properties are characterized. Further, the banana leaf and banana peel’s measurement data are compared with the data obtained using the proposed model. In addition, Root Mean Square Error (RMSE) and R-squared (R 2) are calculated to validate the performance of the proposed model. In case of banana leaf at 68.26% MC, the dielectric constant achieves the value of R 2 and RMSE of 0.98 and 0.0648, respectively. Similarly, dielectric loss achieves the value of R 2 and RMSE of 0.88 and 0.0795, respectively. Further, for banana peel at 80.89% MC, the dielectric constant achieves the value of R 2 and RMSE of 0.99 and 0.2989, respectively. Similarly, dielectric loss achieves the value of R 2 and RMSE of 0.96 and 0.6132, respectively.

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