排序方式: 共有86条查询结果,搜索用时 296 毫秒
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针对羰基铁粉吸收剂在温度较高时易被氧化的问题,采用水热法制备了氧化锌包覆羰基铁粉核壳结构复合粒子,并分别将羰基铁粉和氧化锌/羰基铁粉核壳粒子与石蜡混合,制备复合材料。结果表明,氧化锌纳米棒致密的包覆在羰基铁粉颗粒表面形成海胆状核壳结构复合粒子,正是这种结构将羰基铁粉颗粒与空气隔绝,使得复合粒子的抗氧化性能得到显著改善。与羰基铁粉复合吸波材料相比,氧化锌/羰基铁粉核壳粒子的复合材料吸收峰稍向低频移动,反射损耗小于-5 d B的带宽几乎保持不变,在不改变电磁吸波性能的前提下,提高了羰基铁粉粒子的使用温度。 相似文献
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A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper.Theoretical analysis,an equivalent circuit model and simulated results of a wedge sample show that this material exhibits a negative refraction pass-band around 9.6GHz under normal-incidence and is insensitive to a change in incidence angle.Furthermore,as the angle between the arm of the electric resonators and the strip connecting the arms increases,the frequency range of the pass-band shifts downwards.Consequently,this LHM guarantees a relatively stable torlerence of errors when it is practically fabricated.Moreover,it is a candidate for designing multi-band LHM through combining the resonator pairs with different angles. 相似文献
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通过将单回路镜像对称开口金属环结构印制在高介电常数基板上,实现了一种金属含量比传统负折射材料更少,"双负"通带比全介质负折射材料更宽的负折射材料.分析了高介电常数基板产生负介电常数以及"双负"通带形成的机理,通过仿真实验分析了影响"双负"通带的因素.通过制作样品验证了这一机理实现"双负"的可行性,理论分析与实验结果都表明这种方法可实现较宽频段内的"双负"通带.
关键词:
负折射材料
负介电常数
负磁导率
介质谐振器原理 相似文献
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采用固态烧结工艺制备了位于反铁电/铁电相界附近的掺镧锆锡钛酸铅(PLZST)反铁电陶瓷样品.采用该样品作为阴极材料,研究了其在负脉冲激励电场下的电子发射行为.负脉冲激励下,0.5 mm厚PLZST反铁电陶瓷圆片发射阈值电压为500 V;当激励电压为500 V,抽取电压为3.5 kV时,得到690 A发射电流.结果表明,PLZST反铁电陶瓷发射阈值电压低,发射电流大,即使激励电场低于陶瓷的正向开关电场,仍能得到强发射电流.最后,讨论了PLZST反铁电陶瓷在负脉冲激励下电子发射内在机制.
关键词:
反铁电材料
铁电阴极
电子发射 相似文献
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<正>We simplify the material parameter equation for elliptical cylinder cloaks under transverse-electric and transverse-magnetic models,respectively,and confirm these simplified equations by numerical simulations.As a result,the number of the component parameters is reduced from three to two,which simplifies the design of meta-materials and thus opens up the possibility of achieving elliptical cylinder cloaks in an easy way. 相似文献
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Experimental Verification of Left-Handed Metamaterials Composed of Coplanar Electric and Magnetic Resonators 下载免费PDF全文
We verified experimentally left-handed metamaterials (LHM) composed of coplanar electric and magnetic resonators. A typical LHM sample composed of coplanar resonator unit cells was fabricated, investigated and tested. The experimental results show that the tested sample has a left-handed band of width 1.4 GHz in the X band. The experimental results agree quite well with the simulation ones. Moreover, both the simulation and experimental results show that the LHM under study can automatically achieve good impedance-matching in the left-handed band. 相似文献
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由于具有优异的压电性能,弛豫铁电单晶自上世纪90年代问世以来即成为了铁电压电领域研究的热点材料,并被认为是研发下一代高性能换能器、传感器等器件的重要压电材料。弛豫铁电单晶不但压电常数可达2500 pC/N,约为软性Pb(Zr,Ti)O3(PZT)陶瓷的5倍,而且其电致应变滞后也远小于软性PZT陶瓷。因此,弛豫铁电单晶高压电性能的产生机理一直是铁电压电领域的研究热点。本文主要介绍了弛豫铁电单晶材料在近些年的发展,从本征压电效应(晶格压电畸变)的角度归纳总结了弛豫铁电单晶高压电效应的产生机理,着重探讨了弛豫铁电单晶的重要特点—剪切压电效应。在本征效应的基础上,本文对弛豫铁电单晶压电效应与晶体组分、切向以及温度的关系进行了分析。需要指出的是,目前基于本征角度对弛豫铁电单晶高压电效应的分析仍处于定性的阶段,因而还不能完全排除一些可能导致弛豫铁电单晶高压电效应的非本征物理机制。 相似文献
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