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Permittivity

About: Permittivity is a research topic. Over the lifetime, 35736 publications have been published within this topic receiving 687533 citations. The topic is also known as: electric permittivity & absolute permittivity.


Papers
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Journal ArticleDOI
TL;DR: In this paper, copolymers of aniline and p-phenylenediamine were prepared by joint chemical oxidation of these chemicals with ammonium peroxydisulphate in aqueous medium.
Abstract: Copolymers of aniline and p-phenylenediamine were prepared by joint chemical oxidation of these chemicals with ammonium peroxydisulphate in aqueous medium. The temperature and frequency dependences of the impedance and permittivity of copolymers were measured. The exponential dependence of resistivity on aniline content was observed.

18 citations

Journal ArticleDOI
TL;DR: In this article, the properties of magnetoelectric ceramics were investigated and their functional properties were investigated in order to be designed as components in tunable microwave devices, and it was found that the central stop-band frequency of the designed filter can be tuned with 18 MHz by changing the magnetic field from 0 to 2 kOe.
Abstract: Tunable microwave devices are widely used in radar, telecommunication and radio frequency measurement systems. In recent years, a promising technology for tunable microwave devices, which combines the advantages of using the magnetic and electrical properties of materials as well as their magnetoelectric coupling, has been developed. In the present work, xMnFe2O4-(1 − x)Pb0.988(Zr0.52Ti0.48)0.976Nb0.024O3 ferrite-ferroelectric composites have been prepared and their functional properties were investigated, in order to be designed as components in tunable microwave devices. Structural, microstructural, dielectric and magnetic investigations confirmed the formation of composite ceramics with valuable dielectric and magnetic properties at room temperature. The complex permittivity and permeability of the investigated magnetoelectric ceramics, measured in the frequency range of 1 MHz to 1 GHz, show as a combination of the properties of Pb(Zr,Ti)NbO3 ferroelectric and magnetic MnFe2O4 phases. Experimental measurements and the numerical simulations were done using a high frequency structure simulator (HFSS) which revealed that the investigated composite disk placed on a microstrip line acts as an electromagnetic resonator and it could be consider as a filter with tunable stop-band capabilities controlled by an external magnetic field. It was found that the central stop-band frequency of the designed filter can be tuned with 18 MHz by changing the magnetic field from 0 to 2 kOe.

18 citations

Journal ArticleDOI
TL;DR: In this article, the structural, magnetic and microwave properties of the resulting material were investigated using the sol-gel method, and it was shown that Gd has a much larger ionic radius than Fe, as revealed by the structural analysis.
Abstract: This paper presents a study on attempting to substitute Gd into a Ca-Ba M-type hexaferrite (Ca0.5Ba0.5GdxFe12−xO19, where x = 0, 0.05, 0.1, 0.15, 0.2, 0.25) using the sol–gel method. The structural, magnetic and microwave properties of the resultant material were investigated. Since Gd has a much larger ionic radius than Fe, substitution is not straightforward as revealed by the structural analysis. X-ray diffraction (XRD) patterns revealed some substitution into the M-type phase due to a changing lattice parameter; however, significant quantities of additional phases of hematite (α-Fe2O3) and gadolinium orthoferrite started to form at concentrations of up to Gd = 0.10 and at higher Gd concentrations, respectively. High-resolution transmission electron microscopy of selected compositions showed d-spacings corresponding to the three phases observed in XRD, confirming the incomplete substitution of Gd. Scanning electron microscopy showed platelet-shaped grains. Vibrating sample magnetometry at room temperature showed varied results owing to a myriad of interactions from the hexaferrite and secondary phases. The microwave complex permittivity and permeability in the frequency range of 2–11 GHz showed little frequency dependence with nominal values for the complex permeability. All the compositions exhibit low magnetic losses with frequency except Gd = 0.10. Such type of materials can be used for microwave devices in the low-GHz range and as well as permanent magnets.

18 citations

Journal ArticleDOI
TL;DR: Using both the correlated barrier hopping model accounting for the dielectric losses and the Anderson and Stuart model describing the potential barrier in ionically conducting glasses, the authors in this paper extended the calculation of dielectrics processes in ionic solids to the complex permittivity and compared with the behaviour described by the empirical Cole-Davidson function.
Abstract: Using both the correlated barrier hopping model accounting for the dielectric losses and the Anderson and Stuart model describing the potential barrier in ionically conducting glasses, the calculation of the dielectric processes in ionic solids is extended to the complex permittivity and the results are compared with the behaviour described by the empirical Cole-Davidson function. Experimental results for the ac conductivity obtained on Na 2 O-3SiO 2 glass are fitted by the theoretical behaviour predicted by this model.

18 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023713
20221,673
20211,078
20201,271
20191,324
20181,403