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微波介质复介电系数测试理论及方法 总被引:2,自引:0,他引:2
本文综合介绍了有关微波介质材料复介电子系数的测试理论及其测定方法的系统组成与夹具构造,并对各种测试方法的优缺点,适用范围及其测试精度等进行了说明与比较。 相似文献
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详细分析了基于终端短路波导法材料高温介电性能的测试方法,给出了几种典型透波材料从室温到1600℃的高温介电性能测试与分析结果。由结果可知,由于表面吸附水和体内物理水的存在,一般在1000℃以前,随着温度升高,水分挥发或蒸发,复合材料的介电常数ε和损耗角正切tanδ会有所减小;当温度升至1000℃,由于材料中所吸附的水分基本挥发完全,ε和tanδ降到最小值;当温度高于1000℃时,由于复合材料在制备过程中会引入微量杂质,随着温度升高这些微量杂质开始电离,并产生粒子电导,所以导致ε和tanδ均有较大幅度的上升。本文实测数据可以用于高超声速电磁窗材料透波性能的研究与应用。 相似文献
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晶粒尺寸对Ba0.80Sr0.20TiO3陶瓷介电铁电特性的影响 总被引:8,自引:4,他引:8
利用微波烧结技术和传统烧结技术制备了晶粒尺寸在0.8~15μm的Ba0.80Sr0.20TiO3陶瓷,并对样品的介电特性和铁电特性进行了测试,分析了晶粒尺寸对材料介电和铁电性能的影响,实验结果表明,微波烧结技术可以有效地控制Ba0.80Sr0.20TiO3陶瓷的晶粒尺寸,晶粒尺寸降低,材料的介电常数大幅度提高,弥散指数降低,在外电场作用下,材料介电常数呈现明显的非线性效应,晶粒尺寸的大小对非线性效应产生影响,随晶粒尺寸的降低,材料的矫顽电压,剩余极化和自发极化都有所提高。 相似文献
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对偶极矩作了象观和理论上的描述。甲苯硝基化合物的偶极矩决定于它们的几何结构,可由各键的偶极矩矢量之和作近似计算,它可以用作有机化学以及过程分析化学基础研究的参考。 相似文献
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在炭黑为主要补强材料的轮胎胎面胶行业中,人们对用白炭黑作为补强填料产生了极大的兴趣。这是因为与炭黑填充胶料相比,白炭黑填充胶料的湿路面牵引性能及雪路面牵引性能较好,而且滚动阻力较小。白炭黑在轮胎胎面胶料中的用量逐年增大,可能成为轮胎的主要填充剂。但是,白炭黑填充胶料仍存在一些问题,如未硫化胶料粘度增大,硫化速度慢等。 相似文献
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对PMN-PZN-PT弛豫铁电陶瓷在不同外电场下的介电特性进行了研究。结果表明:直流偏压场与交流测试场对弛豫铁电体的作用相反,增大偏压场导致介电常数的降低,而增大测试场则使介电常数升高。同时频率色散度也呈现了不同的变化趋势。利用超顺电理论及多畴态模型对上述结果进行了定性分析。 相似文献
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Amal Amin Heba Kandil A. M. Rabia Doaa E. El. Nashar Mohamed Nader Ismail 《Polymer-Plastics Technology and Engineering》2018,57(17):1733-1742
Promising nanocomposites (EPDM-nRHP) were prepared from EPDM/ nanosized rice husk powder (nRHP) in the presence of HRH system as modifying dry bonding agent. HRH system comprised hydrated silica, resorcinol and hexamethylenetetramine. Different concentrations from nRHP were used for preparing such nanocomposites. The effect of nRHP was studied on the mechanical and dielectric properties of EPDM-nRHP nanocomposites whether in the presence or absence of HRH system. The presence of HRH modifying system enhanced the dispersion of nRHP in EPDM and consequently improved the mechanical and dielectric properties for the resulting EPDM-nRHP nanocomposites which may be used as electrical insulator. 相似文献
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BaCu(B_2O_5)助烧对CaO-BaO-Li_2O-Sm_2O_3-TiO_2微波介质陶瓷低温烧结和介电性能的影响 总被引:1,自引:0,他引:1
研究了BaCu(B_2O_5)(简写为BCB)掺入对14CaO-4BaO-8Li_2O-12Sm_2O_3-63TiO_2(简写为CBLST)微波介质陶瓷介电性能的影响.用XRD和SEM研究其相组成及微观形貌.结果表明:BaCu(B_2O_5)掺入能显著降低CBLST陶瓷的烧结温度,由1325 ℃降至1100 ℃.1100 ℃烧结2 h后,仍包含正交钙钛矿相和棒状的BST相.掺入6wt% BaCu(B_2O_5)的CBLST陶瓷取得了较好的介电性能:Kr=87.76,tanδ=0.018,TCF=-4.27 ppm/℃(1 MHz). 相似文献
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采用固相烧结反应法制备(Mg1–x,Cax)2Al4Si5O18陶瓷。XRD测试结果表明:0≤x<0.2时,陶瓷以(Mg,Ca)2Al4Si5O18堇青石单一相固溶体形式存在;0.2≤x<0.8时,陶瓷以Mg2Al4Si5O18/CaAl2Si2O8两相复合形式存在;0.8≤x<1.0时,陶瓷以单一相(Ca,Mg)Al2Si2O8固溶体形式存在。SEM结果显示:Ca2+掺杂可以有效地降低堇青石陶瓷的气孔率与微裂纹,并能有效地控制Mg2Al4Si5O18/CaAl2Si2O8复相陶瓷的颗粒分布与晶粒尺寸。微波介电性能测试结果表明:0≤x≤0.4时,(Mg1–xCax)2Al4Si5O18陶瓷介电常数εr为7.0左右;0.6≤x≤1.0时,εr从7.0增加到8.6,然后又降低到6.9。随着x增加,品质因数Qf值从24100GHz降低到4400GHz。但是,在x=0.6时,由于[Si,AlO4]四面体中Al/Si原子排列的有序化,(Mg0.4,Ca0.6)2Al4Si5O18陶瓷Qf值(Qf=5500GHz)比两侧x值成分点Qf值有较大提高。(Mg1–x,Cax)2Al4Si5O18陶瓷谐振频率温度系数在整个x值范围内保持在–20×10–6~–35×10–6℃–1。 相似文献
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Chong You Beh Ee Meng Cheng Nashrul Fazli Mohd Nasir Mohd Shukry Abdul Majid Shing Fhan Khor Mohd Ridzuan Mohd Jamir Emma Ziezie Mohd Tarmizi Kim Yee Lee 《International journal of molecular sciences》2022,23(10)
This paper aims to investigate the dielectric properties, i.e., dielectric constant (ε′), dielectric loss factor (ε″), dielectric tangent loss (tan δ), electrical conductivity (σ), and penetration depth (Dp), of the porous nanohydroxyapatite/starch composites in the function of starch proportion, pore size, and porosity over a broad band frequency range of 5 MHz–12 GHz. The porous nanohydroxyapatite/starch composites were fabricated using different starch proportions ranging from 30 to 90 wt%. The results reveal that the dielectric properties and the microstructural features of the porous nanohydroxyapatite/starch composites can be enhanced by the increment in the starch proportion. Nevertheless, the composite with 80 wt% of starch proportion exhibit low dielectric properties (ε′, ε″, tan δ, and σ) and a high penetration depth because of its highly interconnected porous microstructures. The dielectric properties of the porous nanohydroxyapatite/starch composites are highly dependent on starch proportion, average pore size, and porosity. The regression models are developed to express the dielectric properties of the porous nanohydroxyapatite/starch composites (R2 > 0.96) in the function of starch proportion, pore size, and porosity from 1 to 11 GHz. This dielectric study can facilitate the assessment of bone scaffold design in bone tissue engineering applications. 相似文献
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以EDTA为络合剂,采用聚合物前驱体法合成了SmAlO3微波介质陶瓷粉体,并研究了SmAlO3的制备过程、热分解机理,表征了粉体性质. 结果表明,添加乙二醇制备的干凝胶在550℃以上基本分解完全,800℃煅烧2 h获得正交钙钛矿结构的SmAlO3单相,合成温度从传统固相反应法的1400℃大幅下降到800℃,所得粉体颗粒呈球形,分散性良好,平均粒径约30 nm. 合成粉体可显著提高SmAlO3的烧结性能,SmAlO3陶瓷在1550℃即可烧结致密,相对密度达97.5%,并显示出优良的微波介电性能,相对介电常数为21, 品质因数为77400 GHz, 谐振频率温度系数为-73.2′10-6 ℃-1. 相似文献
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Dhirendra Mohan Ram Prasad Srikumar Banerjee 《Journal of the American Ceramic Society》2001,84(9):2126-2128
Lead magnesium niobate (PMN) and lead iron niobate (PFN) were prepared by the semiwet hydroxide route, and their dielectric properties were measured in temperature ranges around their peak dielectric constants. The dielectric constant of PFN was much larger as compared with that of PMN sintered at the same temperature. The dielectric properties of PMN and PFN are compared and explained on the basis of their structure development. 相似文献