Papers by Author: Zhao Xian Xiong

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Authors: F. Xiao, Zhao Xian Xiong, X.Y. Dong, G.S. Yang
Abstract: Automatic measurement system with multimode for microwave ceramic materials is developed. Based on traditional parallel-plate resonance method, the whole system is composed of a parallel-plate cavity, a vector network analyzer (VNA), an interface card for GPIB to USB, and a PC with measurement programs. Besides the fundamental mode, higher order resonant modes are also measured at the same time. Based on a platform of VEE, a set of analysis software is programmed with the functions of not only automatically calibrating and searching resonant frequencies but also automatically computing and displaying the dielectric parameters of microwave materials with high reliability and efficiency in a wide frequency range.
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Authors: Zhao Xian Xiong, M.Y. Zhou, Hao Xue, Hong Qiu, F. Xiao
Abstract: A new type of porous ceramics, Mg2SiO4, for microwave application with low permittivity and high quality factors were prepared via gel-casting processing in this paper. Microstructure of the ceramics was observed and crystal structure of the samples was also identified. Moreover, emphasis was paid on the characterization of the microwave ceramics. Dielectric properties of the ceramics were measured by an automatic system of microwave measurement, resulting in dielectric constant of 3.51 and quality factor of 11,774 for the ceramic sample at frequency about 10GHz. Mechanical performance of the samples were also evaluated with maximal bending strength of 140MPa.
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Authors: Zhao Xian Xiong, Z.G. Su, Hong Qiu
Abstract: Degradation aging of BaTiO3 microwave ceramic capacitors for EMI applications at highvoltage, AC 10kV, was focused in this paper. Electric performances of the ceramic capacitors were systematically evaluated with thermal shock (5 cycles of –30 °C for 1 h and then 125°C for 1 h), damp heat (100% RH at 40°C for 500 h), and, endurance at high temperature (DC 10 kV at 100°C for 500 h). High reliability for the ceramic capacitor was obtained with optimal ceramic composition, sintering temperature, epoxy resin, curing agent and additives, which was satisfied with practical microwave technologies.
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Authors: He Lan Ye, Zhao Xian Xiong, Hao Xue, Hong Qiu, Chun Xiao Son
Abstract: A new kind of gas sensors were prepared via chemical polymerization of polypyrrole (PPy) as sensitive layer on base of Mg2SiO4 porous ceramics. Thermal stability of the PPy sensitive layer was characterized with thermogravimetric analysis, including TG and DTA. Chemical structure of the samples was identified with X-ray diffraction (XRD) analysis. Microstructure of the PPy film was observed by a scanning electron microscope (SEM). Chemo-electrical relationship of the gas sensors was investigated with the resistance variation of PPy films at different gas concentrations. Based on series of experimental results, linear behavior of the chemo-electrical relationship was obtained for the gas sensor, y=0.00344x+1.33754, with R2=0.9734.
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Authors: Zhao Xian Xiong, F. Xiao, J.R. Huang, Hong Qiu
Abstract: Dielectric constant of Ba2Ti9O20 ceramics are theoretically calculated based on the chemical structure of the oxides and the mixing rule of dielectric material in this paper. Meanwhile, the microwave properties (εr, Q and τf) of practical Ba2Ti9O20 ceramics are experimentally measured at microwave frequencies. Some of useful suggestions are therefore provided for material optimization of practical ceramics.
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Authors: Zhao Xian Xiong, Guo Feng Zhang, Hao Xue, Jin Bao Huang, Qiang Zheng, Bai Qiang You
Abstract: τMicrowave dielectric properties of 0.95MgTiO3-0.05CaTiO3 ceramics and their performances as H-shaped microstrip patch antenna were investigated. Best values of dielectric constant (εr) and quality factor (Q×f) of 19.00 and 66800GHz, respectively, were obtained for the microwave ceramics sintered at 1300°C for 3h. A near-zero temperature coefficient of resonant frequency (τf) of -4.7ppm/°C was obtained for the ceramics with sintering 1280°C for 3h. A new kind of H-shaped microstrip patch antenna with two resonant frequencies was fabricated by using of this kind of ceramics as antenna substrate. The return loss bandwidth of the patch antenna was extended with the increasing of substrate thickness at both resonant frequencies of the antennas, around 1.530GHz and 2.750GHz, respectively.
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Authors: S.S. Cheng, J. Luo, Zhao Xian Xiong
Abstract: Microwave ceramics of Ba(Mg0.2/3Zn0.8/3Nb2/3)O3 and Ba1-xSrx(Mg0.2/3Zn0.8/3Nb2/3)O3 were synthesized with conventional solid-state reaction method. Dielectric properties of the samples were studied as functions of compositions and sintering temperatures. Experimental results show that a higher Q×f value is reached by substituting Zn ions with Mg ions and a near-zero temperature coefficient of resonant frequency is obtained by replacing Ba ions with Sr ions.
272
Authors: H.G. Yu, C.X. Song, Z.H. Shen, Zhao Xian Xiong
Abstract: (Zr0.8Sn0.2)TiO4 ceramics with additives of ZnO, CuO, Bi2O3 and MnCO3 were prepared by the conventional mixed oxide route. They were characterized by TG/DTA, SEM, EDS and a network analyzer. Microwave properties of (Zr0.8Sn0.2)TiO4 ceramics were investigated as a function of the amount of additives. The optimal values of dielectric constant er, quality factors Q*f and temperature coefficient of resonant frequency tf reached 35, 51000 GHz and 26 ppm/°C respectively with 2.0 wt% MnCO3. Specimens with additives of ZnO, CuO and Bi2O3 had microwave properties of er = 35 ~ 39, Q*f = 9000 ~ 35000 GHz and tf = 15~40 ppm/°C.
91
Authors: Wei Li, Zhao Xian Xiong, Hao Xue, Chun Xiao Song, Hong Qiu
Abstract: CaCu(3+ x)Ti4O12 (x = 0, 0.001, 0.002, 0.004 and 0.008) ceramics with variation in copper micro-scale excess were prepared via solid-state reaction, Aqueous technology of tape casting was applied to obtain thick films of, about 100 μm in thickness. Crystal phases of the samples were identified by XRD. SEM of samples revealed that copper micro-scale excess can accelerate some important solid phase reactions in the sintering process, most because of liquid phase sintering mechanism. EDX analysis indicated that copper micro-scale excess could compensate for a lack of copper in sintering process. The Cu3.004 sample exhibited the best dielectric properties with a very low dielectric loss (0.029), while retaining a very high dielectric constant (91,536), and the Cu3.002 and Cu3.004 samples exhibited a well frequency and temperature stability which was of significant industrial relevance. In this work, it was concluded that a certain amount of Cu micro-scale excess could improve dielectric properties, frequency stability and temperature stability of CCTO ceramics.
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Authors: Jin Bao Huang, Yi Xiang Cai, Zhao Xian Xiong, Hao Xue
Abstract: 0.95MgTiO3-0.05CaTiO3 (95MCT) microwave dielectric ceramics was prepared solid-state reaction method. Effect of H3BO3 additive and forming pressure on sintering process, microstructure and microwave dielectric properties of 95MCT were investigated. The result showed that the additive of H3BO3 can lower the sintering temperature of 95MCT, and improve the densification of 95MCT. MgTi2O5 was found as mesosphere, which can be effectively suppressed through the additive of H3BO3. Excellent microwave dielectric properties of ceramics was obtained when the H3BO3 additive was 0.50wt%. The best value of dielectric constant (εr), quality factor (Q×f) and temperature coefficient of resonant frequency (τf ) of 21.54, 67,286GHz and-4.1ppm/oC was obtained for the ceramics with sintering 1220oC for 2h.
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