Preparation and High-Frequency Dielectric Properties of Cu/SiO2 Composites

2015 ◽  
Vol 655 ◽  
pp. 174-177
Author(s):  
Kai Sun ◽  
Run Hua Fan ◽  
Zi Dong Zhang ◽  
Xi Hua Zhang ◽  
Ke Lan Yan ◽  
...  
Keyword(s):  
Phase Composition ◽  
Dielectric Properties ◽  
High Frequency ◽  
Selective Reduction ◽  
Reduction Process ◽  
Silica Matrix ◽  
Dielectric Constants ◽  
Impedance Analyzer ◽  
Copper Particles ◽  
Metal Contents

In this paper, Cu/SiO2composites with different metal contents were successfully prepared by a selective reduction process. The phase composition and microstructure of composites were analyzed by XRD and SEM, respectively. The results show that spherical copper particles are uniformly distributed in silica matrix. The impedance and permittivity of composites were tested with RF impedance analyzer (0.1~1 GHz). It is indicated Cu/SiO2composites exhibit capacitive character. In addition, the dielectric constants get enlarged due to the enhancement of interface polarization.

Effect of Sr/Ba Ratio on Dielectric Properties of BSTN Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 125-128 ◽  
Author(s):  
Zong Hui Zhou ◽  
Xin Cheng ◽  
Pi Yi Du ◽  
Jun Chang ◽  
Shi Feng Huang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Phase Composition ◽  
Dielectric Properties ◽  
Perovskite Phase ◽  
Tungsten Bronze ◽  
Dielectric Constants ◽  
Composite Ceramics ◽  
Impedance Analyzer ◽  
Applied Frequency ◽  
Two Phases

The phase composition of (1-x)BaO·xSrO·0.7TiO2·0.3Nb2O5 (BSTN) composite ceramics was analyzed by XRD, and the effect of Sr/Ba ratio on the dielectric properties of BSTN was investigated by impedance analyzer. The results showed that any sample with different x value contained two phases-the perovskite phase and the tungsten bronze phase. The dielectric constants of BSTN basically decreased while the tanδ increased with the increase in x value. Both dielectric constant and tanδ decreased with the applied frequency increased for the same x value. There were two Curie points for BSTN composite ceramics. The first one belonging to the perovskite phase decreased with the increase in x value, but the second one belonging to the tungsten bronze phase kept almost constant at about 300°C.

A facile method for the preparation of aliphatic main-chain benzoxazine copolymers with high-frequency low dielectric constants

2018 ◽  
Vol 9 (21) ◽  
pp. 2913-2925 ◽  
Author(s):  
Ming Zeng ◽  
Jiangbing Chen ◽  
Qingyu Xu ◽  
Yiwan Huang ◽  
Zijian Feng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Main Chain ◽  
Polymerization Kinetics ◽  
Dielectric Constants ◽  
Low Dielectric

The effects of the reaction solvent on the preparation, polymerization kinetics, and high-frequency dielectric properties of aliphatic main-chain benzoxazine copolymers were investigated.

Effects of Mn Doping on Dielectric Properties of BSTN Ceramics

2008 ◽  
Vol 368-372 ◽  
pp. 72-74
Author(s):  
Xin Cheng ◽  
Zong Hui Zhou
Keyword(s):  
Phase Transition ◽  
Phase Composition ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Phase Transition Temperature ◽  
Tungsten Bronze ◽  
Dielectric Constants ◽  
Composite Ceramics ◽  
Mn Doping ◽  
Applied Frequency

The effects of Mn doping on the phase composition and dielectric properties of (1-x)BaO·xSrO·0.7TiO2·0.3Nb2O5 (BSTN) composite ceramics was investigated. The results showed that the dielectric constants of 0.7BaO·0.3SrO·(0.7-z)TiO2·0.3Nb2O5·zMnO2 (BSTNM) composite ceramics basically decreases as the content of doped MnO2 increases at the same applied frequency, while tanδ decreases when value z≤0.01 but increases when value z>0.01. The phase transition temperature of tungsten bronze phase in BSTNM composite ceramics increases with the increase of value z.

Dielectric Properties of PMN/CB/CIIR Composites

2009 ◽  
Vol 66 ◽  
pp. 234-237 ◽  
Author(s):  
Hao Yan ◽  
Zhi Xiong Huang ◽  
Yan Bing Wang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Carbon Black ◽  
Lead Titanate ◽  
High Frequency ◽  
Dielectric Constants ◽  
Frequency Range ◽  
Magnesium Niobate ◽  
Chlorobutyl Rubber

The Magnesium Niobate-Lead Titanate (PMN) / conductive carbon black (CB)/ chlorobutyl rubber(CIIR) composites were prepared by blending-vulcanization method, and the dielectric properties were studied. The results showed that the dielectric constant and dielectric loss of composites increased nonlinearly when increasing the content of PMN or CB. From the curve of dielectric constant vs frequency, it is obtained that in the frequency range from 103 to 106 Hz, the dielectric constant of PMN/CB/CIIR composites decreased with the frequency increasing and the dielectric constants are more stable under high frequency.

scholarly journals Preparation and Characterization of Electrospun Fluoro-Containing Poly(imide-benzoxazole) Nano-Fibrous Membranes with Low Dielectric Constants and High Thermal Stability

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 537
Author(s):  
Meng-Ge Huangfu ◽  
Deng-Xiong Shen ◽  
Xin-Xin Zhi ◽  
Yan Zhang ◽  
Yan-Jiang Jia ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Dielectric Properties ◽  
High Frequency ◽  
Rapid Development ◽  
Dielectric Constants ◽  
Polymer Materials ◽  
Aromatic Diamines ◽  
Low Dielectric ◽  
Fibrous Membranes ◽  
Poly Imide

The rapid development of advanced high-frequency mobile communication techniques has advanced urgent requirements for polymer materials with high-temperature resistance and good dielectric properties, including low dielectric constants (low-Dk) and low dielectric dissipation factors (low-Df). The relatively poor dielectric properties of common polymer candidates, such as standard polyimides (PIs) greatly limited their application in high-frequency areas. In the current work, benzoxazole units were successfully incorporated into the molecular structures of the fluoro-containing PIs to afford the poly(imide-benzoxazole) (PIBO) nano-fibrous membranes (NFMs) via electrospinning fabrication. First, the PI NFMs were prepared by the electrospinning procedure from organo-soluble PI resins derived from 2,2′-bis(3,4-dicarboxy-phenyl)hexafluoropropane dianhydride (6FDA) and aromatic diamines containing ortho-hydroxy-substituted benzamide units, including 2,2-bis[3-(4-aminobenzamide)-4-hydroxylphenyl]hexafluoropropane (p6FAHP) and 2,2-bis[3-(3-aminobenzamide)-4-hydroxyphenyl]hexafluoropropane (m6FAHP). Then, the PI NFMs were thermally dehydrated at 350 °C in nitrogen to afford the PIBO NFMs. The average fiber diameters (dav) for the PIBO NFMs were 1225 nm for PIBO-1 derived from PI-1 (6FDA-p6FAHP) precursor and 816 nm for PIBO-2 derived from PI-2 (6FDA-m6FAHP). The derived PIBO NFMs showed good thermal stability with the glass transition temperatures (Tgs) over 310 °C and the 5% weight loss temperatures (T5%) higher than 500 °C in nitrogen. The PIBO NFMs showed low dielectric features with the Dk value of 1.64 for PIBO-1 and 1.82 for PIBO-2 at the frequency of 1 MHz, respectively. The Df values were in the range of 0.010~0.018 for the PIBO NFMs.

Dielectric Properties of CaCu3Ti4O12 Ceramics

2010 ◽  
Vol 434-435 ◽  
pp. 253-255
Author(s):  
Jing Han You ◽  
Xiao Yang Gong ◽  
Tong Wei Li ◽  
Qing Dong Chen ◽  
Li Ben Li
Keyword(s):  
Activation Energy ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Frequency ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Debye Relaxation ◽  
Relaxation Theory ◽  
Reaction Method ◽  
Theoretical Results

CaCu3Ti4O12 ceramics were prepared by the traditional solid-state reaction method and the dielectric properties were investigated, the activation energy and relaxation time factor of the samples were calculated. Debye relaxation theory was attempted to analyze the experimental datum, the static and high-frequency dielectric constants were obtained according to Cole-Cole spectra. The temperature dependence of the dielectric constant of CaCu3Ti4O12 were fitted by computer and the theoretical results nearly agree with experimental results.

Dielectric properties of the hydrates of argon and nitrogen

1968 ◽  
Vol 46 (10) ◽  
pp. 1673-1681 ◽  
Author(s):  
S. R. Gough ◽  
E. Whalley ◽  
D. W. Davidson
Keyword(s):  
Dielectric Properties ◽  
High Frequency ◽  
Dielectric Constants ◽  
Water Molecules ◽  
Circular Arc ◽  
Circular Arcs ◽  
In Series ◽  
Temperature And Pressure ◽  
Water Lattice ◽  
Static Dielectric Constants

The dielectric relaxation of water in the structure I clathrate hydrates of argon and nitrogen was studied over a range of temperature and pressure. Hydrates were slowly grown at pressures of 1 to 2 kbar in a coaxial cell enclosed in a pressure vessel. The complex permittivity loci resemble circular arcs with static dielectric constants of ~56 at 0 °C and high-frequency dielectric constants of 2.85 ± 0.05. Relaxation near 0 °C is about as slow as in ice I, but activation energies and entropies are much smaller. Formation of Bjerrum defects probably takes place preferentially near the occasional sites at which argon and nitrogen molecules have replaced water molecules in the lattice. The much faster relaxations found previously in the isostructural hydrates of ethers arise from orientational defects induced in the water lattice by the encaged molecules, a small proportion of which may form hydrogen bonds with water. The effect of small gaps in series with samples showing circular-arc dispersion behavior was evaluated.

Dielectric Properties of ZrO2 Doped on NiO at High Frequency

2014 ◽  
Vol 895 ◽  
pp. 216-220
Author(s):  
Aishah Syed Salim Sharifah ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Frequency ◽  
Phase Identification ◽  
Dielectric Analysis ◽  
Frequency Range ◽  
Conventional Solid State Reaction ◽  
Impedance Analyzer ◽  
Microstructural Observation ◽  
Scanning Electron

ZrxNi1-xO was prepared by conventional solid state reaction. The properties of undoped and ZrO2 doped NiO ceramics have been studied. The raw mixture of ZrO2 and NiO were ball milled for 24 hours. The samples were calcined at 1000°C for 2 hours, pressed into pellet shape at 200 MPa and sintered at 1300°C for 10 hours. The sintered samples were subjected to XRD, Scanning Electron Microscopy (SEM) and Impedance Analyzer for phase identification, microstructural observation and dielectric analysis. The grains size decrease with the increment of dopant amount. Enhanced dielectric constant was observed in the ZrO2 doped NiO with x= 0.02 for the frequency range from 1MHz to 1GHz. The dielectric constant of sintered ZrxNi1-xO decreased with an increasing frequency. The result indicates that Zr ions have effectively changed the dielectric properties of NiO.Keywords: NiO, Zr-doped, XRD, SEM, Dielectric.

Dielectric Properties of Li-Zr Modified NiO at High Frequency

2016 ◽  
Vol 846 ◽  
pp. 326-330
Author(s):  
C.T. Ping ◽  
Syarifah Aishah Syed Salim ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Phase Formation ◽  
Solid State Reaction ◽  
High Frequency ◽  
Single Phase ◽  
Impedance Analyzer ◽  
Single Phase Formation

Li+ and Zr2+ codoped NiO ceramics was successfully prepared from the mixture of commercial Li2CO3, ZrO2 and NiO using solid state reaction. The mixture of varies Li+ concentration (x = 0.01, 0.02, 0.03, 0.05 and 0.1), Zr2+ (y = 0.02) and NiO were ball milled for 24 hours. The samples were calcined at 1000oC for 2 hours, pressed into pellet shape at 250 MPa and sintered at 1280°C for 10 hours. The sintered pellets were subjected to XRD, SEM, density testing and Impedance analyzer. XRD result shows the single phase formation of LixNi1-x-0.02Zr0.02O. The grain becomes larger with the increament of Li+ mole %. The dielectric constant of LixNi1-x-0.02Zr0.02 decrease with the increasing frequency. The NiO codoped with Li+ and Zr2+ can be use excellently at high frequencies.Keywords: NiO doped Li+ and Zr2+, dielectric constant, high frequency

Preparation and Dielectric Property of C/SiO2 Composite via Self-Assembly

2016 ◽  
Vol 848 ◽  
pp. 369-373
Author(s):  
Zi Dong Zhang ◽  
Xiu Jie Ji ◽  
Chen Qin ◽  
Hui Min Wang ◽  
Shu Hui Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Dielectric Constant ◽  
Composite Material ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Self Assembly ◽  
High Frequency ◽  
Assembly Process ◽  
Composite Matrix ◽  
Impedance Analyzer

In this paper, C/SiO2 bulk composite was prepared via SiO2 microspheres’ self-assembly process combined with heat treatment. SEM and impedance analyzer was used to investigate the microstructure and high-frequency dielectric properties of the composites. The results show that SiO2 microspheres constituted the composite matrix, whose porosity was slightly higher than the densest hexagonal stacking. Sheet carbon distributed in pores formed by SiO2 microspheres. The real and imaginary parts of the dielectric constant of the composite material increased with the content of carbon, but decreased with the frequency. The permittivity of C/SiO2 composite could be adjusted by control the concentration of PVA solution.

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