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综述了CaTiO3基微波介质陶瓷的发展与研究现状,比较分析了CaTiO3、Ca1-xLn2/3x TiO3、CaO-Li2O-Ln2O3-TiO2与Ca(B1/23 B'1/25 )O3微波介质陶瓷的重要微波介电性能,讨论了Bi2O3、B2O3、ZnO等低熔点烧结助剂对CaTiO3基微波介质陶瓷结构、介电性能的影响以及该系陶瓷制备的新工艺,指出了目前急需解决的问题与今后的发展方向. 相似文献
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通过XRD、SEM等分析手段,结合介电性能测试结果,探讨了两种不同的原料粉体引入方式H1及H2,对Li2O-Nb2O5-TiO2陶瓷体系中"M-相"与Li2TiO3固溶体(Li2TiO3ss)共存的复合陶瓷材料(H1及H2陶瓷)的烧结行为、微观结构以及微波介电性能的影响。采用H2方式制备的H2陶瓷,1100℃烧结2h,材料具有较优异的微波介电性能:介电常数εr=40.2,Q×f值高达9900GHz,频率温度系数τf=4.6×10-6/℃,是一种性能优异的微波介质陶瓷材料。 相似文献
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采用机械合金法制备了Mg4Nb2O9微波介质陶瓷,研究了添加V2O5和Li2CO3对其烧结性能、显微结构及微波介电性能的影响。结果表明:添加V2O5和Li2CO3可有效降低Mg4Nb2O9陶瓷烧结温度(940℃),获得亚微米级(0.86μm)微波介质陶瓷。1.50%V2O5和1.50%Li2CO3(质量分数)共掺杂Mg4Nb2O9陶瓷于940℃烧结获得良好微波介电性能:介电常数为12.7,品质因数为45028GHz,谐振频率温度系数为-7.65×10-5℃-1,有望成为新一代低温烧结基板材料。 相似文献
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《Journal of Modern Optics》2013,60(4):363-369
Microwave holography differs from optical holography in three distinct ways. First, in microwave holography the reference field may be eliminated and replaced by correct phasing of the local oscillator within the microwave receiver. Second, the reference wave need not coexist in time with the signal or object field. Third, it is not necessary that the object field be measured simultaneously across the array. Aside from these fundamental differences, which give the microwave holographer additional freedom in system design, another practical difference should be noted. Because of the long wavelength used in microwave holography, the aperture must be huge to obtain images with fine resolving power. Such apertures are often mechanically unstable. By introducing adaptivity or self-cohering into the creation and measurement of the reference field, it is possible to ‘straighten out’ a distorted microwave aperture. An instrument which performs these operations is called a radio camera. A twodimensional radar map of a few blocks of a small town in Pennsylvania illustrates the process. 相似文献
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Microwave Absorbing Materials 总被引:21,自引:0,他引:21
Available data on microwave absorbing materials finding engineering applications or potentially attractive for use in dielectric, magnetic, and ferroelectric–seignettomagnetic absorbers are summarized. 相似文献
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《IEEE transactions on instrumentation and measurement》1977,26(2):95-98
Modified cavity perturbation methods for permittivity measurements of yarn and textile are described. A cylindrical cavity which is split into equal parts is designed to operate in the TE011 mode. The dielectric yarn is placed across the midplane of the cavity and a textile sample is placed in the cavity on a low-loss dielectric sheet in annular form. The shift in the resonant frequency and change in Q-factor are measured and the complex permittivity is calculated. 相似文献
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1.IntroductionNumerousstudieshaveshownthatmicrowavesin-teringofceramicshassomeadvantagesoverconven-tionalsinteringprocess,suchassavingsinenergyandprocessingtime,volumetricandrapidheating,lowerdensificationtemperature,uniformmicrostruc-tureofsinteredceramics,improvedmaterialsperfor-mance,productionofnewmaterialsandmicrostruc-tureetc..Basedontheformofmicrowaveenergyused,microwavesinteringcanbebasicallydividedintomicrowaveheatingsintering,microwaveplasmaheatingsinteringandstepsioteringwhichcombin… 相似文献
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Microwave processed composite materials 总被引:3,自引:0,他引:3
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