Papers by Keyword: Dielectric

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Authors: Hashem Al-Mattarneh, Abdullah Alwadie, Ahmad Malkawi, Muhd Fadhil Nuruddin
Abstract: A new measurement system is developed to monitor the early hydration of cementitious materials based on measured dielectric properties of the material in low electromagnetic frequency range. The objectives of this paper were to evaluate the changes in the electromagnetic properties for samples with different fly ash content and to establish the reliability of the measurement technique by comparing with results obtained by traditional method such as thermal method that is either time consuming or impractical. The method adopted in the present experimental work is a parallel plate electrode system (PPES). The suggested monitoring device for concrete hydration and strength development is based on the relationship between the electromagnetic properties such as dielectric constant, loss factor and the strength development during hydration process and curing time. In this research the electromagnetic properties of concrete is found to be dependent on the hydration and strength of concrete. Therefore the development of microstructure and concrete compressive strength can be determined by monitoring its electromagnetic properties in the frequency range of 1 to 100 kHz.
Authors: Rong Wang Guo, Juan Zhang, Zhuo Fu, Bo Yu Liu
Abstract: Simple dielectric or magnetic absorbing material medium's capacity to absorb the electromagnetic wave is limited so that it can't very well meet technical requirements. At the historic moment ,absorbing material mixed dielectric and magnetic medium development arises. There is a very complicated relationship between effective electromagnetic parameters of a mixture of dielectric and magnetic medium and its components .The ratio of different not only lead to different effective electromagnetic parameters but also have different reflection and transmission of electromagnetic parameters. According to the existing model and comparing the different reflection outcome of mixing ratio of the electromagnetic medium , this article mainly carry on the calculation of effective electromagnetic parameters and analysis of reflectivity to get the optimization of the hybrid medium’ absorbing properties.
Authors: Don Kyu Lee
Abstract: Various studies are being conducted on the application of DBD (Dielectric barrier discharges). The internal dielectric has a very important characteristic on DBD, thus we analyze of the characteristics on dielectric barrier discharges depending on the relative permittivity and frequency. Through simulation, the discharge voltage was calculated based on relative permittivity and frequency of real used dielectrics (Green sheet, Down dielectric, white dielectric). We investigate that increased relative permittivity and fast frequency occur the decrease of the firing voltage. Also, we investigate the frequency dependence of the dielectric constant and dielectric loss of dielectric layers measured at a frequency region of 100Hz to 10MHz. In a condition of drive within 1MHz, with regard to the change of real and imaginary part according to frequency, it has quite stable dielectric constant in the condition of drive within 1MHz.
Authors: Hong Qiang Shan, Xin Ming Wang, Wei Ping Li
Abstract: In order to obtain the high dielectric constant and low loss materials by using the two main methods for synergy, the 3-phases TiO2/(PVDF+Fe3O4) composites with the fixed Fe3O4 fraction have been prepared by using a simple blending and hot-molding technique. The dielectric measurement results show that no synergistic effect but a cancellation effect has been found here, corresponding to the decrease of dielectric constant and conductivity. The value of the relative dielectric constant dropped to the original level of polymer matrix. The reasons for the counter result are present here. It is helpful and reference for the proper choice for multiphase composite system.
Authors: X.A. Mei, Min Chen, W.K. An, Chong Qing Huang, J. Liu, A.H. Cai
Abstract: Pr-doped bismuth titanate (BixPryTi3O12: BPT) thin films with random orientation were fabricated on Pt/Ti/SiO2/Si substrates by rf magnetron sputtering technique, and the structures and Raman spectra of the films were investigated. XRD studies indicated that all of the BPT films consist of single phase of a bismuth-layered structure, showing a highly (117) oriented preferential growth with a minor fraction of (00l) orientation. For an increasing degree of Pr doping, Raman spectra studies revealed a substantial hardening of the vibration involving Bi atoms at the perovskite A site, whereas the Bi mode at the Bi2O2 layer is negligibly changed. From a comparison with a simple mass consideration, we identify a precise cation distribution, indicating a pronounced site selectivity of Pr ions for the A site for y ~ 1.2.
Authors: Dariusz Bochenek, Ryszard Skulski, Paweł Wawrzała, Przemysław Niemiec
Abstract: We present the technology of the solid solution with formula (1-y)[(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3]-yPb(Fe1/2Nb1/2)O3 where x=0.25, y=0.1 i.e. 0.9(0.75PMN-0.25PT)-0.1PFN. The addition of PFN decreases the temperature of final sintering and as a result such composition is interesting material for multilayer ceramic capacitors (MLCC). The powder of 0.9(0.75PMN-0.25PT)-0.1PFN has been obtained in three steps. In first step we obtained MgNb2O6. In second step FeNbO4 was obtained. In final third step the 0.9(0.75PMN-0.25PT)-0.1PFN was obtained from mixed powders MgNb2O6, FeNbO4 and PbO and TiO2. For obtained ceramics the following investigations have been made: XRD patterns, microstructure, EDS and main dielectric properties v.s. temperature. It has been stated that obtained ceramic powder is a good material for obtaining MLCC
Authors: I. Albinsson, R. Bokalawela, M.A.K.L. Dissanayake, B.E. Mellander, K. Rundgren
Authors: Somnath Paul, Arnab Gangopadhyay, A. Sarkar
Abstract: Gadolinium (Gd) is a weak magnetic element at room temperature. Gadolinium oxide (Gd2O3) is a poor semiconductor with para-magnetism. In this work Gadolinium oxide is prepared from the thermal dissociation of Gadolinium acetate. The average cluster size is found to be dependent on the number of the sintering time. In this present work an attempt has been made to characterize the developed Gadolinium oxide. Experimental probes used to characterize it are optical absorbance (UV-VIS); Fourier transformed infra red (FTIR) spectroscopy, DC current voltage characteristics (CVC) and photo-sensitivity studies of the developed specimens. Gadolinium oxide exhibits a good optical sensing property.
Authors: Jing Hua Xia, David M. Martin, Sethu Saveda Suvanam, Carl Mikael Zetterling, Mikael Östling
Abstract: LaxHfyO nanolaminated thin film deposited using atomic layer deposition process has been studied as a high-K gate dielectric in 4H-SiC MOS capacitors. The electrical and nano-laminated film characteristics were studied with increasing post deposition annealing (PDA) in N2O ambient. The result shows that high quality LaxHfyO nano-laminated thin films with good interface and bulk qualities are fabricated using high PDA temperature.
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