High frequency properties of microwires
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2021-07-01 09:59
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BARANOV, Serghei Alexei. High frequency properties of microwires. In: Materials Science and Condensed Matter Physics, Ed. 7, 16-19 septembrie 2014, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2014, Editia 7, p. 297.
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Materials Science and Condensed Matter Physics
Editia 7, 2014
Conferința "Materials Science and Condensed Matter Physics"
7, Chișinău, Moldova, 16-19 septembrie 2014

High frequency properties of microwires


Pag. 297-297

Baranov Serghei Alexei12
 
1 Institute of Applied Physics, Academy of Sciences of Moldova,
2 T.G. Shevchenko State University of Pridnestrovie, Tiraspol
 
Disponibil în IBN: 19 martie 2019


Rezumat

Glass-coated amorphous magnetic microwires are produced by the Taylor-Ulitovsky method (see in Ref. [1-8). The alloy is heated, in an inductor, up to the melting point. The portion of the glass tube adjacent to melting metal softens, enveloping the metal droplet. Before entering into their microwave properties, let us briefly summarize some important aspects of these composite materials. Glass-coated magnetic microwires are characterized by a nucleus out of a magnetic alloy, structurally amorphous and metallic conductor, with diameter between around 2 and 20 μm, covered by a Pyrex-like coating 2 to 10 μm thick. That coating, besides insulating the metallic nucleus from corrosion and electrical points of view, induces strong mechanical stresses in that nucleus that couple with magnetostriction to determine large magnetoelastic anisotropy, and consequently a unique magnetic behavior. Particularly, the strong magnetoelastic anisotropy in magnetostrictive Fe-rich alloys amorphous microwires gives rise to the existence magnetic bistability characterized. These microwires exhibit also outstanding high frequency properties as for example natural ferromagnetic resonance, NFMR, appearing typically within the frequency range 0,1 to 12 GHz depending on the magnetic alloy composition. A correlation between the frequency of natural ferromagnetic resonance (NFMR) (1 to 12 GHz), determined from the dispersion of permeability, and alloy composition (or magnetostriction between 1 and 40 ppm) of glass-coated microwires has been systematically confirmed. Absorption of composite (microwire pieces embedded in a polymer matrix) screens has been experimentally investigated. Parallel theoretical studies suggest that a significant fraction of the absorption can be ascribed to a geometrical resonant effect, while a concentration effect is expected for the thinnest microwires. We present the results of a research regarding new applications of cast amorphous microwires in the realization of some new composite material and the possibility to use it in electromagnetic shielding and protection equipment manufacturing. The spontaneous NFMR phenomena observed in glass-coated microwires has opened the possibility of developing novel materials with broad-band of radio absorbing materials. The microwave electromagnetic response has been analyzed for a composite consisting of dipoles of amorphous magnetic glass-coated microwires in a dielectric. This material can be employed for radio absorbing screening.