Abstract
Reduction in the skin effect for the sintered Si nanopolycrystalline body as an electricity conductor at a high frequency due to its nanostructure was studied. Singular disappearance of electrical resistances near a local high magnetic harmonic frequency of a few MHz was observed. This phenomenon has not been observed for conventional ferromagnetic metals. The measured electrical resistances changed to almost 0 mΩ at room temperature. At the same time, negative resistance of the sintered Si nanopolycrystalline body was observed. It will be applicable to electronic transmittance lines or semiconductors. Numerical calculation was also performed on the electrical resistance with frequency dependency while considering the electric field and magnetic field in the sintered Si nanopolycrystalline body. The experimental and calculated results are compared. The calculation could explain the variation of the relative permittivity of the Si nanopolycrystalline body and the phenomenon for the theoretical disappearance of the resistivity at the MHz frequency. Reduced Si nanoparticles from SiO2powder were synthesized by laser ablation in liquid. A Si nanopolycrystalline body made of the reduced Si nanoparticles was fabricated. It was found by measuring the magnetization property of the body of the sintered Si nanopolycrystalline body which is ferromagnetic. Dangling bonds (unpaired electrons) have long been known to occur due to defects in Si crystals. Perfect Si without defective crystals has no dangling bonds. However, Si nanoparticles have many dangling bonds. High-density dangling bonds cause the sintered Si nanopolycrystalline body to have ferromagnetism. In this study, the density of the unpaired electrons in the sintered Si nanopolycrystalline body was observed using ESR. It has been clarified that the Si nanopowder and the sintered Si nanopolycrystalline body have numerous dangling bonds. Both densities of the dangling bonds were evaluated.
Highlights
Reduction of AC resistance owing to the skin effect at high frequency from MHz to GHz in electronic devices or transmittance lines has been attracting attention due to its ability to realize low-power consumption
We can expect that low-loss electric power lines and low-power-consumption electronic devices with low heat generation can be achieved by developing metals and semiconductors that have the reduced skin effect [1,2,3,4]
Singular disappearance of electrical resistances near a local high magnetic harmonic frequency of a few MHz has been observed in the experiments
Summary
Reduction of AC resistance owing to the skin effect at high frequency from MHz to GHz in electronic devices or transmittance lines has been attracting attention due to its ability to realize low-power consumption. A multilayered material, which consists of different materials, such as metal and magnetic, is used for reducing the skin effect when a high-frequency current is conducted. A technology has been developed to make electrical circuits at low temperatures of below 470 K using paste or ink consisting of Au [7], Ag [8, 9], Cu [10], Fe [11, 12], Al [11, 12], and Mg [12] nanoparticles owing to the phenomena of melting point depression.
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