Comparative Study Of Dielectric Properties Research Articles

Comparative study of dielectric properties of Ternary Alkali Halide crystals

Comparative study of dielectric properties of Ternary Alkali Halide crystals

Comparative study of dielectric properties of the PVDF composites filled with spherical and rod-like BaTiO3 derived by molten salt synthesis method

In the molten salt environment, the BaTiO3 spherical nanoparticles (BTNPs) and BaTiO3 nanorods (BTNRs) have been synthesized, respectively, in which spherical TiO2 and rod-like BaTi2O5 are precursors. The dissolution–precipitation is the main dominated mechanism in the formation of BTNPs, while the dissolution–diffusion is the main mechanism responsible for the formation of BTNRs. The latter is also called as topochemical mechanism, which is associated with the assembly of [TiO6] octahedron units in the transformation from BaTi2O5 to BaTiO3. By using these two kinds of BT as fillers, polyvinylidene fluoride (PVDF)-based composites, BTNPs/PVDF and BTNRs/PVDF, have been constructed and their dielectric properties have been investigated. It was found that there were three main factors related to filler morphology affecting the dielectric properties of the composites, i.e., intrinsic polarization of filler, the interface polarization and electric field distribution between the filler and the matrix. Though the spontaneous polarization of 600-nm-sized BTNPs is larger, the interfacial area of BTNRs/PVDF composite is larger than that of BTNPs (600 nm)/PVDF composite, which is advantageous to enhance the interface polarization. Moreover, the analysis through Potential-Across model revealed that BTNRs/PVDF composite has stronger electric field intensity distribution across BTNRs filler in comparison with BTNPs/PVDF, which plays the key role in improving the dielectric properties of composites. This work not only presents the BTNRs/PVDF composite with good dielectric performance, the related design and the theory analysis also facilitate the development of more new high dielectric composites based on morphology control of ferroelectric filler.

Comparative study of dielectric properties of the skin of human and laboratory animals

Comparative study of dielectric properties of the skin of human and laboratory animals

The dielectric properties and dielectric mechanism of perovskite ceramic CLST/PTFE composites

Polytetrafluorethylene (PTFE) composites filled with perovskite (Ca,Li,Sm)TiO3 (CLST) dielectric ceramic of various volume fractions filler up to 60% were prepared. The effects of volume fraction of ceramic filler on the microstructure and dielectric properties of the composites have been investigated. A comparative study of dielectric properties of experiment and modeling analysis has been carried out at high frequencies for the CLST/PTFE composites. The results indicate that both the dielectric constant and the dielectric loss increase with the filler. The CLST/PTFE composite with 40% ceramic has exhibited good dielectric properties: e r = 7.92 (~10 GHz), tan δ = 1.2 × 10−3 (~10 GHz), and τ f = −45 ppm/°C. The dielectric properties are obviously better than most composites reported previously at high frequencies in the aspects of dielectric loss and thermal stability. The dielectric constant and dielectric loss of composites predicted by the Rother–Lichtenecker equation and the general mixing model are in good agreement with the experiment data when the volume fraction of ceramic is less than 40%. When the volume fraction of the ceramic is more than 40%, the deviation occurs. By introducing the correction factor, the theoretical values of the dielectric constant agrees well with the experimental values.

Comparative Study of Dielectric Properties of Chicken Feather/Kenaf Fiber Reinforced Unsaturated Polyester Composites

The electrical properties of chicken feather fiber (CFF) and kenaf fiber (KF) unsaturated polyester (UP) composites have been studied with reference to fiber loading and frequency. Tests were carried out to compare the suitability of the two different composites as a dielectric material. The chicken feather fiber unsaturated polyester composite exhibited an overall lower dielectric constant, dissipation factor, and loss factor compared to the kenaf fiber unsaturated polyester composites. The values were high for the composites with fiber contents at 40%. The dielectric value increments were high at low frequencies, and they gradually reached significantly lower values at higher frequencies. Based on the results it was judged that chicken feather fiber composites would be suitable for application as high speed printed circuit board (PCB) material with good frequency stability at 1 MHz. Finally, an attempt was made to correlate the experimental values with theoretical calculations.

Comparative Study of Dielectric Properties and Relative Magnetic Permeability of Nano and Bulk Mg Zn Spinel Ferrite

Comparative Study of Dielectric Properties and Relative Magnetic Permeability of Nano and Bulk Mg Zn Spinel Ferrite

Relaxation investigations in polysulfone: Thermally stimulated discharge current and dielectric spectroscopy

The temperature and electric field dependence of dielectric relaxation have been investigated in amorphous polysulfone (PSF) samples using thermally stimulated discharge current (TSDC) and AC dielectric measurement. All measurements were performed on solution grown thin films of thickness 50 μm. The nature of relaxation mechanisms in amorphous PSF is discussed on the basis of TSDC and dielectric measurement results. The comparative studies of dielectric properties with TSDC indicated a strong resemblance between the two techniques. Polysulfone (PSF) films are characterized by two TSDC peaks, i.e. β peak at 348 K and α peak at 470 K. The depolarization current for the β peak increases linearly with poling field. The peak obtained at lower temperature (i.e. β peak) is associated with dipolar relaxation and the other one obtained at high temperature (i.e. α peak), which appears due to the α relaxation.

COMPARISON OF MICROWAVE AND ELECTRICAL PROPERTIES OF SELECTED CONDUCTING POLYMERS

Microwave properties of conductive polymers is crucial because of their wide areas of applications such as coating in reflector antennas, coating in electronic equipments, frequency selective surfaces, EMI materials, satellite communication links, microchip antennas, and medical applications. This work involves a comparative study of dielectric properties of selected conducting polymers such as polyaniline, poly(3,4-ethylenedioxythiophene), polythiophene, polypyrrole, and polyparaphenylene diazomethine (PPDA) in microwave and DC fields. The microwave properties such as dielectric constant, dielectric loss, absorption coefficient, heating coefficient, skin depth, and conductivity in the microwave frequency (S band), and DC fields were compared. PEDOT and polyaniline were found to exhibit excellent properties in DC field and microwave frequencies, which make them potential materials in many of the aforementioned applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 504–508, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23091

Comparison of microwave and electrical properties of selected conducting polymers

AbstractMicrowave properties of conductive polymers is crucial because of their wide areas of applications such as coating in reflector antennas, coating in electronic equipments, frequency selective surfaces, EMI materials, satellite communication links, microchip antennas, and medical applications. This work involves a comparative study of dielectric properties of selected conducting polymers such as polyaniline, poly(3,4‐ethylenedioxythiophene), polythiophene, polypyrrole, and polyparaphenylene diazomethine (PPDA) in microwave and DC fields. The microwave properties such as dielectric constant, dielectric loss, absorption coefficient, heating coefficient, skin depth, and conductivity in the microwave frequency (S band), and DC fields were compared. PEDOT and polyaniline were found to exhibit excellent properties in DC field and microwave frequencies, which make them potential materials in many of the aforementioned applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 504–508, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23091

Comparative study of dielectric properties of MgNb2O6 prepared by molten salt and ceramic method

Magnesium niobate (MgNb2O6) powder was synthesized by the conventional ceramic route as well as by the molten salt route using a eutectic mixture of NaCl-KCl as the salt and Mg(NO3)2-6H2O and TiO2 as the starting materials. Pure phase of MgNb2O6 could be obtained by the molten salt method at 1100°C. However, in ceramic method the pure phase of MgNb2O6 was obtained by heating at 1025°C for 20 h. On sintering at 1100°C the dielectric constant and dielectric loss of MgNb2O6 obtained by the molten salt method was found to be 19.5 and 0.004 at 100 kHz at room temperature. Lower values were obtained for these oxides prepared by the ceramic route, 16.6 and 0.000518, respectively. In both cases the dielectric constant was quite stable with frequency.

Comparative study of dielectric properties of K2ZnCl4 and K2Zn1−xFexCl4 in the vicinity of incommensurate-commensurate phase transition

Comparative study of dielectric properties of K2ZnCl4 and K2Zn1−xFexCl4 in the vicinity of incommensurate-commensurate phase transition

Electrical and structural characteristics of oxides grown from polycrystalline silicon

A comparative study of dielectric properties of polysilicon oxide with silicon dioxide, grown on single crystal silicon, shows that the former is more conducting due to the presence of asperites at polysilicon/SiO2 interface. This paper also reports attempts made to improve the electrical properties of polysilicon oxide by investigating the effects of oxidation temperature, polysilicon deposition temperature and doping on current field characteristics of polyoxide. Higher doping and higher oxidation temperature yield smoother interface with higher breakdown voltages and lower leakage currents. Surface morphology of polyoxide under different process conditions is also studied.