Papers by Keyword: dielectric characteristics

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Authors: Jian Zhu Ye, Gan Qing Zuo, Song Wang, Chao Xie, Yang Wang, Yan Hui Shi
Abstract: Based on the composite dielectric polarization theory, dielectric permittivity, dissipation factor and loss angle tangent of hydrated paraffin versus temperature and power supply frequency were analyzed. The effect of different water contents in paraffin on its dielectric characteristics was also studied. The more the water content in hydrated paraffin, the greater the dielectric parameters, dissipation factor can reach 1.48 when the water contents was 15%. They can provide references for theoretical researches and industrial applications on removal of paraffin that condense on the interior walls of oil pipes in oil extraction by electric heating method.
2544
Authors: J. Subocz, A. Valozhyn, P. Berczyński, E. Herko
Abstract: The paper presents the results of research into the dielectric characteristics of modified Kapton and Upilex polyimides with C60 – fullerene contents of 0.1-2.0 % wt. The influence of temperature and frequency on the time constants of b-relaxation of modified polyimides is shown.
157
Authors: Chien Min Cheng, Kai Huang Chen, Hung Chi Yang, Cheng Fu Yang, Wen Cheng Tzou, Ming Chang Kuan, Fuh Cheng Jong
Abstract: In order to improve the sintering density and dielectric properties of the lead-free K0.5Na0.5NbO3-based ceramics, by the use of solid-state reaction, part of the Nb atoms are substituted by the Ta atoms to form K0.5Na0.5Nb0.95Ta0.05O3 ceramics and the dielectric characteristics are detail investigated in this letter. It is found that the phases of K0.5Na0.5Nb0.95Ta0.05O3 ceramics are pure perovskite with typical orthorhombic symmetry, in addition, no other secondary phases could be certified. For pure K0.5Na0.5Nb0.95Ta0.05O3 ceramics, the shapes of the grains are quadrate and which would due to the increase of the porosity and can not be eliminated easily. Because of the phase stability of pure K0.5Na0.5Nb0.95Ta0.05O3 ceramics is limited to 1140 °C in this study, higher sintering temperature (over than 1140 °C) is not suitable for the fabrication of K0.5Na0.5Nb0.95Ta0.05O3 ceramics. Moreover, the Ta atoms in the K0.5Na0.5NbO3-based ceramics could be used to improve the dielectric properties effectively, and it also reveals lower Curie temperature and lower phase transition temperature than the pure K0.5Na0.5NbO3 ceramics. In this letter, for 1120°C-sintered K0.5Na0.5Nb0.95Ta0.05O3 ceramics, the optimum bulk density is 95.6 % of the theorical density, the Curie temperature is 380 °C, and the optimum relative dielectric constant is 6107 at 10 kHz.
285
Authors: Cheng Fu Yang, Chien Min Cheng, Ho Hua Chung, Chao Chin Chan
Abstract: 5~15 wt% MgO-CaO-Al2O3-SiO2 (MCAS, fabricated by sol-gel method) glass is used as the sintering aid of AlN ceramics. The sintering is proceeded from 1350oC~1550oC, scanning electron microscope is used to observe the sintered morphologies and X-ray diffraction pattern are used to confirm the crystal structures. From the SEM observations, as 10wt% and 15wt% MCAS is added, AlN ceramics can be densified at 1500oC and 1450oC, which are much lower than the before studies were. From the X-ray diffraction patterns, the crystal phases of MCAS-AlN ceramics are AlN, Al2O3, and cordierite phases. In this study, the dielectric characteristics of MCAS-AlN ceramics are also developed as a function of MCAS content and sintering temperature.
1868
Authors: Chien Min Cheng, Ming Chang Kuan, Kai Huang Chen, Chia Chi Shih, Jiann Sheng Jiang
Abstract: Lead-free potassium sodium niobate ceramic, with the nominal composition of K0.5Na0.5NbO3, were synthesized by conventional solid state sintering, and its dielectric, ferroelectric, and piezoelectric properties were characterized as a function of sintering temperature. The orthorhombic to tetragonal phase transition (TO-T) temperature of K0.5Na0.5NbO3 ceramic sample was about 220°C, and its Curie temperature was about 420°C. The high bulk density was obtained for all compositions by solid state sintering in air. Bulk density was increased with temperature and it reached to 4.4 g/cm3. The K0.5Na0.5NbO3 ceramic sample sintered at 1100°C was optimized densification properties. In addition, the ferroelectric loop and dielectric characteristics dependence of different sintering temperature for K0.5Na0.5NbO3 ceramic sample was obtained. Finally, we found that the piezoelectric constant (d33) was 160 pC/N, high remanent polarization (Pr) was 33mC/cm2, and high electromechanical coupling coefficients (kP) was about of 45%.
994
Authors: Chien Min Cheng, Kai Huang Chen, Yuan Tai Hsieh, Fuh Cheng Jong
Abstract: BaTiO3/ which has good dielectric properties, they were widely used in ceramic capacitors, thermistors, etc. In this study, BaTiO3/ ceramics prepared by sol-gel powder, then mixed in the organic polymer polyether imide (PEI) and dispersant (surface active agents) and silane coupling agent (Silane Coupling Agent) of the composite material on flexible substrates, And analysis of its properties and electrical properties. Increase by a ceramic powder, to explore the impact of the substrate. In the physical analysis is used XRD, SEM to measure the intensity of crystalline phase and surface uniformity of the electrical measurement using HP4294 measuring dielectric constant and dielectric loss.
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