Electromagnetic Materials and Devices最新文献

{"title":"High-Frequency Permeability of Fe-Based Nanostructured Materials","authors":"M. Han","doi":"10.5772/INTECHOPEN.86403","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.86403","url":null,"abstract":"Frequency dependence of permeability of magnetic materials is crucial for their various electromagnetic applications. In this chapter, the approaches to tailor the high-frequency permeability of Fe-based nanostructured materials are discussed: shape controlling, particle size distribution, coating treatments, phase transitions and external excitations. Special attention is paid on the electromagnetic wave absorbing using these Fe-based magnetic materials (Fe-Si-Al alloys, Fe-Cu-Nb-Si-B nanocrystalline alloys and Fe nanowires). Micromagnetic simulations also have been presented to discuss the intrinsic high-frequency permeability. Negative imaginary part of permeability ( μ ″ < 0) is proved possible under the spin transfer torque effect.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126057347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Semiconductor Surface State Engineering for THz Nanodevices","authors":"I. Cortes-Mestizo, E. Briones, L. I. Espinosa-Vega, V. Méndez-García","doi":"10.5772/intechopen.86469","DOIUrl":"https://doi.org/10.5772/intechopen.86469","url":null,"abstract":"This chapter is dedicated to study the semiconductor surface states, which com-bined with nanolithography techniques could result on remarkable properties of advanced nanodevices suitable for terahertz (THz) signal detection or harvesting. The author presents the use of low-dimensional semiconductor heterostructures for the development of the so-called self-switching diodes (SSDs), studying by simulation tool key parameters in detail such as the shape and size of the two-dimensional electron gas system. The impact of the geometry on the working principle of the nanodevice and the effects on current-voltage behavior will be described in order to acquire design guidelines that may improve the performance of the self-switching diodes when applied to low-power square-law rectifiers as well as elements in rectennas by appropriately setting the size of the components.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128999870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dielectric Responses in Multilayer Cf/Si3N4 as High-Temperature Microwave-Absorbing Materials","authors":"Heng Luo, L. Deng, P. Xiao","doi":"10.5772/intechopen.82389","DOIUrl":"https://doi.org/10.5772/intechopen.82389","url":null,"abstract":"High-temperature microwave-absorbing materials are in great demand in mili-tary and aerospace vehicles. The high-temperature dielectric behavior of multilayer C f /Si 3 N 4 composites fabricated by gelcasting has been intensively investigated at temperature coverage up to 800°C in the X-band (8.2–12.4 GHz). Experimental results show that the permittivity of Si 3 N 4 matrix exhibits excellent thermo-stability with temperature coefficient lower than 10 − 3 °C − 1 . Taking temperature-dependent polarized bound charge and damping coefficient into consideration, a revised dielectric relaxation model with Lorentz correction for Si 3 N 4 ceramics has been established and validated by experimental results. Besides, a general model with respect to permittivity as a function of temperature and frequency has been established with the help of nonlinear numerical analysis to reveal mechanisms of temperature-dependent dielectric responses in C f /Si 3 N 4 composites. Temperature-dependent permittivity has been demonstrated to be well distributed on circular arcs with centers actually kept around the real ( ε ′ ) axis in the Cole-Cole plane. Furthermore, space charge polarization and relaxation are discussed. These findings point to important guidelines to reveal the mechanism of dielectric behavior for carbon fiber functionalized composites including but not limited to C f /Si 3 N 4 composites at high temperatures, and pave the way for the development of high-temperature radar absorbing materials. dielectric Si 3 permittivity and loss thermo-stability temperature coefficient − 3 dielectric as-prepared 3 of for permittivity of electric polarization and relaxation of migration for graphitic basal planes of short carbon fibers. addition room-temperature model concerning frequency-dependent permittivity available when extended into the full range of temperature coverage up to 800°C, an empirical equation with respect to temperature-dependent permittivity of multilayer C f /Si 3 N 4 composites has been established. It is concluded that the measured complex permittivity of multilayer C f /Si 3 N 4 composites is well distributed on circular arcs with centers actually kept around the real ( ε ′ ) axis in ( ε ′ , ε ″ ) complex plane. Furthermore, the relaxation time as a function of temperature also has been derived. Results suggest that the relaxation time for multilayer C f /Si 3 N 4 composites increases from 216.1 to 250.2 ps when heated from","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129740139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ferromagnetism in Multiferroic BaTiO3, Spinel MFe2O4 (M = Mn, Co, Ni, Zn) Ferrite and DMS ZnO Nanostructures","authors":"K. Verma, Ashish Sharma, N. Goyal, R. Kotnala","doi":"10.5772/intechopen.82437","DOIUrl":"https://doi.org/10.5772/intechopen.82437","url":null,"abstract":"Multiferroic magnetoelectric material has significance for new design nanoscale spintronic devices. In single-phase multiferroic BaTiO 3 , the magnetism occurs with doping of transition metals, TM ions, which has partially filled d-orbitals. Interestingly, the magnetic ordering is strongly related with oxygen vacancies, and thus, it is thought to be a source of ferromagnetism of TM:BaTiO 3 . The nanostructural MFe 2 O 4 (M = Mn, Co, Ni, Cu, Zn, etc.) ferrite has an inverse spinel structure, for which M 2+ ions in octahedral site and Fe 3+ ions are equally distributed between tetrahedral and octahedral sites. These antiparallel sub-lattices (cations M 2+ and Fe 3+ occupy either tetrahedral or octahedral sites) are coupled with O 2- ion due to superexchange interaction to form ferrimagnetic structure. Moreover, the future spintronic technologies using diluted magnetic semiconductors, DMS materials might have realized ferromagnetic origin. A simultaneous doping from TM and rare earth ions in ZnO nanoparticles could increase the antiferromagnetic ordering to achieve high-Tc ferromagnetism. The role of the oxygen vacancies as the dominant defects in doped ZnO that must involve bound magnetic polarons as the origin of ferromagnetism.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115688049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Terahertz Sources, Detectors, and Transceivers in Silicon Technologies","authors":"Li Zhuang, Cao Rui, Tao Xiaohui, Jiang Lihui, Rong Dawei","doi":"10.5772/INTECHOPEN.86468","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.86468","url":null,"abstract":"With active devices lingering on the brink of activity and every passive device and interconnection on chip acting as potential radiator, a paradigm shift from “ top-down ” to “ bottom-up ” approach in silicon terahertz (THz) circuit design is clearly evident as we witness orders-of-magnitude improvements of silicon THz circuits in terms of output power, phase noise, and sensitivity since their inception around 2010. That is, the once clear boundary between devices, circuits, and function blocks is getting blurrier as we push the devices toward their limits. And when all else fails to meet the system requirements, which is often the case, a logical step forward is to scale these THz circuits to arrays. This makes a lot of sense in the terahertz region considering the relatively efficient on-chip THz antennas and the reduced size of arrays with half-wavelength pitch. This chapter begins with the derivation of conditions for maximizing power gain of active devices. Discussions of circuit topologies for THz sources, detectors, and transceivers with emphasis on their efficacy and scalability ensue, and this chapter concludes with a brief survey of interface options for channeling THz energy out of the chip.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"334 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116907231","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electromagnetic Function Textiles","authors":"Hong Xiao, Meiwu Shi, Jianying Chen","doi":"10.5772/INTECHOPEN.85586","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.85586","url":null,"abstract":"This chapter is about the electromagnetic (EM) functional textiles. There are three parts including the EM properties of the textiles, the EM functional textile materials, and the application of the EM functional textiles. In the first part, we outline the textile materials including the fibers, yarns, and fabrics and their EM properties. Generally, textiles are poor in EM properties such as low conductivity and low dielectric and magnetic properties. In the second part, EM functional textiles are defined and the manufacture method is stated. The EM functional fibers and yarns and fabrics can be got by various methods; the EM properties can be improved to a high level. In the third part, several typical EM functional textiles are introduced. These textiles are antistatic textiles, EM shielding textiles, EM scattering textiles, and two-dimensional and three-dimensional frequency selective textiles. The principle, the processing methods, the properties of the static electro or EM shielding or EM scattering or frequency selection, and so on are described one by one in detail.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129756727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ferrite Materials and Applications","authors":"Tsun-Hsu Chang","doi":"10.5772/INTECHOPEN.84623","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.84623","url":null,"abstract":"This chapter starts from a generalized permeability and aims at providing a better understanding of the ferrites behavior in the microwave fields. The formula of the generalized permeability explains why the permeability of the ferrimagnetic or even the ferromagnetic materials strongly depends on the applied magnetic bias and the polarization of the wave. Right-hand circularly polarized (RHCP) wave may synchronize with the precession of the magnetic moment, resulting in a strong resonant effect. Characterizing the ferrites ’ properties, including the complex permittivity, the saturation magnetization, and the resonance linewidth, will be discussed. We then utilize these properties to design and fabricate various microwave devices, such as phase shifters, circulators, and isolators. Detailed analysis and simulation to demonstrate how these ferrite devices work will be shown. The mechanism will be discussed.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128128087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal- and Dielectric-Loaded Waveguide: An Artificial Material for Tailoring the Waveguide Propagation Characteristics","authors":"V. Kesari","doi":"10.5772/INTECHOPEN.82124","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82124","url":null,"abstract":"In the present chapter a number of loaded structures are studied with circular cross-section to explore the deviation in their dispersion characteristics from their parent circular waveguide. The dielectric and/or metal loading to the waveguide tailors its dispersion characteristics. In general, the dielectric depresses and the metal elevates the dispersion characteristics from the characteristics of their parent circular waveguide. The axial periodicity results in periodic dispersion characteristics with a lower and an upper cut-off frequency (bandpass). However such a characteristic is not reported for the azimuthal periodic structures. The bandpass characteristic arises due to the shaping of the dispersion characteristics. Therefore the dispersion shaping is only possible with axial periodicity and not with the azimuthal periodicity. The sensitivity of the structure (geometry) parameters on the lower and upper cut-off frequencies, the extent of passband and the dispersion shaping are also included. In the axial periodic structures, the periodicity is found to be the most sensitive parameter for tailoring the dispersion characteristics and the disc-hole radius is the most sensitive parameter for shifting the dispersion characteristics over the frequency axis.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114795864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dielectric Losses of Microwave Ceramics Based on Crystal Structure","authors":"H. Ohsato, J. Varghese, H. Jantunen","doi":"10.5772/INTECHOPEN.82483","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82483","url":null,"abstract":"So far, many microwave dielectric materials have been investigated for a range of telecommunication applications. In dielectrics, the three main dielectric properties are quality factor ( Q ), dielectric constant and temperature coefficient of resonant frequency. Among these, the most essential dielectric property is Q . More specifi-cally, Q is the inverse of the dielectric loss (tan δ ); thus Q = 1/tan δ . There are two kinds of losses: those depending on crystal structure and losses due to external factors. The former is intrinsic losses such as ordering, symmetry, and phonon vibration. The latter is extrinsic losses due to factors such as grain size, defects, inclusions and distortion. In this chapter, the authors present the origin of dielectric losses based on the crystal structure. An ideal and well-proportional crystal structure constitutes a low loss material. Most dielectric materials are paraelectrics with inversion symmetry i and high symmetry. In general, it is believed that ordering gives rise to a high Q , on which many researchers are casting doubt. In the case of complex perovskites, the symmetry changes from cubic to trigonal. Ordering and symmetry should be compared with the structure. In this chapter, three essential conditions for the origin of high Q such as high symmetry, compositional ordering and compositional density are presented.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131231708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electromagnetic Wave Absorption Properties of Core-Shell Ni-Based Composites","authors":"Biao Zhao, Rui Zhang","doi":"10.5772/INTECHOPEN.82301","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82301","url":null,"abstract":"Currently, high efficiency electromagnetic wave absorption plays an important role to keep away from the detection of aircraft by radar and reduce information leakage in various electronic equipment. Among the candidates of electromagnetic absorbers, ferromagnetic Ni materials possess high saturation magnetization and high permeability at high frequency (1–18 GHz), which is widely used to prepare thinner absorbing materials along with strong electromagnetic absorption properties. However, the metallic materials usually have relatively high electrical conductivity, and their permeability decreases rapidly at high frequency thanks to the eddy current losses, which is generally named as skin-depth effect. To address this issue, one effective way is to design core-shell structured Ni based composites combining magnetic cores with dielectric shells. This chapter focuses on the state-of-the-art of the microwave absorption properties of Ni-based core-shell composites, and the related electromagnetic attenuation theory about how to enhance absorption properties is also discussed in detail.","PeriodicalId":247660,"journal":{"name":"Electromagnetic Materials and Devices","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130662569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}