Dielectric Properties of SiAlON Ceramics

2008 ◽  
Vol 403 ◽  
pp. 125-128 ◽  
Author(s):  
Do Kyung Kim ◽  
Ha Neul Kim ◽  
Young Hoon Seong ◽  
Seung Soo Baek ◽  
Eul Son Kang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Microwave Frequency ◽  
Tangent Loss ◽  
Hot Press ◽  
Frequency Range ◽  
Cationic Species ◽  
Press Method ◽  
Resonator Method

The dielectric properties of -SiAlON and various cations doped -SiAlON bulk ceramics prepared by a hot-press method were investigated. The dielectric properties (dielectric constant and tangent loss) were characterized by a post-resonator method (Hakki-Coleman method) at room temperature in the microwave frequency range. The effect of z-values about -SiAlON was examined, and also the effects of various interstitial cations on dielectric properties of -SiAlON were studied. Dielectric properties of -SiAlON were compared with those of Si3N4 and -SiAlON and their relationship between the dielectric properties and the cationic species of SiAlON were discussed.

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.

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 Studies of Admicelled Natural Rubber with Poly(3-Trimethoxysilylpropyl Methacrylate)

2013 ◽  
Vol 844 ◽  
pp. 373-376
Author(s):  
Suparat Nooma ◽  
Rathanawan Magaraphan
Keyword(s):  
Dielectric Constant ◽  
Composite Materials ◽  
Dielectric Properties ◽  
Chemical Modification ◽  
Natural Rubber ◽  
Microwave Frequency ◽  
Dielectric Studies ◽  
Frequency Range ◽  
Admicellar Polymerization ◽  
Methoxy Groups

In this work, 3-trimethoxysilylpropyl methacrylate (MPS) was used as a substrate for coating on natural rubber (NR) particles by admicellar polymerization. The incorporation of MPS monomer, consisting of silicon element and 3 reactive methoxy groups (R-Si(OCH3)), is expected to increase dielectric properties of NR. Under the admicellar polymerization, the R-Si(OCH3) groups can be hydrolyzed and condensed into polysiloxane existed on NR particles. This method aims to prepare composite materials from NR and MPS with various amounts of MPS. The effects of microwave frequency and chemical modification by admicellar polymerization were studied. The dielectric properties of admicelled natural rubber (adNR) with PMPS were investigated at 20 °C in a frequency range extended from MHz to GHz. The results showed that the dielectric constant of adNR increased with PMPS contents. To study the effect of crosslinking on the dielectric properties of adNR, the dielectric spectroscopy measurements were performed on prevulcanized and non-prevulcanized adNR. The investigation showed that the dielectric constant of non-prevulcanized adNR was less than prevulcanized adNR.

THE DIELECTRIC PROPERTIES OF SELECTED BASALTS

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 135-139 ◽  
Author(s):  
W. Hansen ◽  
W. R. Sill ◽  
S. H. Ward
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Room Temperature ◽  
Frequency Dispersion ◽  
Nitrogen Atmosphere ◽  
Frequency Range ◽  
Dielectric Constant And Loss ◽  
Identical Composition ◽  
Titanium Compounds

Basaltic samples of known chemical composition were measured for dielectric constant and loss tangent in the frequency range 100 hz to 50 Mhz. All samples were prepared and measured by a contact substitution method in a dry nitrogen atmosphere at room temperature. The measurements indicated a general spectrum of dielectric constant with a range of 10–65 at 100 hz to 7–15 at 50 Mhz with frequency dispersion observed to be minimal above 1 Mhz. The loss tangent decreases from a range .2–.9 at 100 hz to a range .02–.15 at 100 khz. A finer‐grained sample was observed to have higher dielectric properties below 1 Mhz than a coarser‐grained sample of identical composition. A qualitative and subsequent quantitative study of possible compositional effects indicated that iron‐titanium compounds may be responsible for observed variations in the dielectric spectra of typical basalts.

Preparation and Characterization of CaCu3Ti4O12 Ceramics by Cold Isostatic Press Forming

2008 ◽  
Vol 368-372 ◽  
pp. 123-125
Author(s):  
Jie Li ◽  
Hao Xue ◽  
Zhao Xian Xiong
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Frequency Range ◽  
Cold Isostatic Press ◽  
Temperature Range ◽  
Press Forming ◽  
Conventional Sintering ◽  
Sintering Method

CaCu3Ti4O12 (CCTO) ceramics were prepared by cold isostatic press (CIP) forming combined with the conventional sintering method. The effects of calcining temperature on properties of CCTO ceramics were investigated. The dielectric properties as the function of temperature at typical frequencies were measured in the temperature range from 243 to 363 K. In addition, the dielectric properties and complex impedances at room temperature were analyzed in a frequency range from 20 Hz to 106 Hz. The results showed that CCTO ceramics with dielectric constant higher than 104 were obtained. Compared with the dry press forming, CCTO ceramics prepared by CIP had more homogeneous grains, less porosity and better dielectric properties.

scholarly journals Bi2O3-Modified Ceramics Based on BaTiO3 Powder Synthesized in Water Vapor

Inorganics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 8 ◽  
Author(s):  
Anastasia Kholodkova ◽  
Aleksey Smirnov ◽  
Marina Danchevskaya ◽  
Yurii Ivakin ◽  
Galina Muravieva ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Water Vapor ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Frequency Range ◽  
Batio3 Powder ◽  
Strength Determination ◽  
Water Vapor Atmosphere ◽  
Room Temperature Dielectric Constant

Bi2O3 was investigated in the role of a modifier for BaTiO3 powder synthesized in a water vapor atmosphere at 200 °C and 1.55 MPa. Modification was aimed at increasing the sinterability of the powder as well as improving the structural and dielectric properties of the obtained ceramics. The morphology and phase contents of the synthesized BaTiO3 powder were controlled by the methods of SEM and XRD. Properties of pure and Bi-doped BaTiO3 ceramics were comprehensively studied by XRD, SEM, dielectric spectroscopy, and standard approaches for density and mechanical strength determination. Doping with Bi2O3 favored BaTiO3 ceramic densification and strengthening. The room-temperature dielectric constant and the loss tangent of Bi-doped BaTiO3 were shown to stabilize within the frequency range of 20 Hz to 2 MHz compared to non-doped material. The drop of dielectric constant between room temperature and Curie point was significantly reduced after Bi2O3 addition to BaTiO3. Bi2O3 appeared to be an effective modifier for BaTiO3 ceramics produced from non-stoichiometric powder synthesized in water vapor.

Dielectric Properties of Alumina Ceramics in the Microwave Frequency at High Temperature

2007 ◽  
Vol 124-126 ◽  
pp. 743-746 ◽  
Author(s):  
Min Kyu Park ◽  
Ha Neul Kim ◽  
Seung Su Baek ◽  
Eul Son Kang ◽  
Yong Kee Baek ◽  
...  
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Microwave Frequency ◽  
Dielectric Measurement ◽  
Alumina Ceramics ◽  
Frequency Range ◽  
Beam Focusing ◽  
Half Wavelength ◽  
Optimum Specimen

The dielectric properties of alumina ceramics have been measured using a free-space time-domain technique from room temperature to 1400 oC in the frequency range 8.2 – 12.4 GHz. The effects of thickness and lateral size of specimen were investigated with comparing the measured values to the calculated ones based on the half-wavelength and the Gaussian beam focusing. From these results the optimum specimen dimension for the high temperature dielectric measurement was suggested with experimental verification.

INFLUENCE OF La2O3 ADDITIONS ON CHEMICAL DURABILITY AND DIELECTRIC PROPERTIES OF BOROALUMINOSILICATE GLASSES

2012 ◽  
Vol 19 (06) ◽  
pp. 1250062 ◽  
Author(s):  
X. H. ZHANG ◽  
Y. L. YUE ◽  
H. T. WU
Keyword(s):  
Dielectric Properties ◽  
Chemical Durability ◽  
Tangent Loss ◽  
Frequency Range ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Weight Losses ◽  
Quenching Method ◽  
Scanning Electron

Boroaluminosilicate glasses containing La2O3 were prepared by the normal quenching method. The glass transition temperatures (Tg) were measured by differential scanning calorimetry (DSC). The structural role of RO was investigated by nuclear magnetic resonance (NMR). Chemical durability was evaluated by weight losses of glass samples after immersion in HC1 solution. High resolution scanning electron microscopy (HR-SEM) was used to examine the surface micrographs of corroded glass samples. The dielectric constant and tangent loss were measured in the frequency range 10–106 Hz. The results revealed that chemical durability and dielectric properties increased with increasing La2O3 content.

Effect of Sintering Temperature on Structure and Dielectric Properties of Lead Free K0.5Na0.5NbO3 Prepared via Hot Isostatic Pressing

2017 ◽  
Vol 888 ◽  
pp. 42-46 ◽  
Author(s):  
Fatin Khairah Bahanurdin ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Grain Size ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Hot Isostatic Pressing ◽  
Solid State Reaction Method ◽  
Lead Free ◽  
Tangent Loss ◽  
Isostatic Pressing ◽  
Tan Δ

In this research, alkaline niobate known as K0.5Na0.5NbO3 (KNN) lead-free piezoelectric ceramic was synthesis by solid state reaction method which pressing at different sintering temperatures (1000 °C and 1080 °C) prepared via hot isostatic pressing (HIP)). The effect of sintering temperature on structure and dielectric properties was studied. The optimum sintering temperature (at 1080 °C for 30 minutes) using hot isostatic pressing (HIP) was successfully increase the density, enlarge the particle grain size in the range of 0.3 µm – 2.5 µm and improves the dielectric properties of K0.5Na0.5NbO3 ceramics. The larger grain size and higher density ceramics body will contribute the good dielectric properties. At room temperature, the excellent relative permittivity and tangent loss recorded at 1 MHz (ɛr = 5517.35 and tan δ = 0.954), respectively for KNN1080HIP sample. The KNN1080HIP sample is also exhibits highest relative density which is 4.485 g/cm3. The ɛr depends upon density and in this work, the density increase as the sintering temperature increase, which resulting the corresponding ɛr value also increases.

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