Papers by Keyword: Glass Coated Microwires

Abstract: This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.Please make the page settings of your word processor to A4 format (21 x 29,7 cm or 8 x 11 inches); with the margins: bottom 1.5 cm (0.59 in) and top 2.5 cm (0.98 in), right/left margins must be 2 cm (0.78 in).We shall be able to publish your paper in electronic form on our web page http://www.scientific.net, if the paper format and the margins are correct.Your manuscript will be reduced by approximately 20% by the publisher. Please keep this in mind when designing your figures and tables etc.

Abstract: Using magnetic characterization, electronic and optical microscopy we studied magnetic properties and different kind of defects in glass-coated microwires containing Co. We observed that Co addition allows improvement of magnetic softness. We also observed the oxygen presence in “defective” regions on the metallic nucleus surface and indications of chemical interaction between the glass-coating and the metallic nucleus.

Abstract: The effect of annealing under applied stress on magnetic properties of Co-based or CoFeNi-based glass-coated microwires was studied. It was found that CoFeNi-based microwires became bistable after annealing because of changing of magnetostriction constant sign, while Co-based microwires keep S-shape of hysteresis loop. The domain wall dynamics of microwires which became bistable was also investigated and it was shown that microwires with acquired bistability are more suitable for applications.

Abstract: In this paper we report on fabrication and characterization of nearly-zero magnetostriction Co₆₉Fe₄Cr₄Si₁₂B₁₁ amorphous microwires produced by two different methods: i-fabricated by combination of usual Tailor-Ulitovski method allowing rapid quenching of composite glass coated microwires following by glass removal techniques (with diameter about 90 μm); ii-produced by Tailor-Ulitovski method with consequent glass removal and warm drawing (at 300 °C). In first case the metallic nucleus diameter has been about 90 μm and after drawing we obtained microwires with diameter about 55 μm. Drawn samples have been annealed at temperatures between 250 and 450 °C. We studied GMI effect (dependence of impedance, Z, on applied magnetic field H) and hysteretic magnetic properties in produced microwires. Ferromagnetic magnetic without glass coating with good magnetic and mechanical properties and GMI effect have been obtained. We can tailor the microwires magnetic properties for its application in magnetic sensors through the selection of adequate thermal treatment conditions.

Abstract: In this paper we report on fabrication and characterization of a novel glass coated Ni₂MnGa glass coated microwires with metallic nucleus diameter of 44 μm prepared the modified Taylor-Ulitovsky method. First magnetic and structural characterization have been performed.

Abstract: Glass-coated Cu-Mn-Ga microwires were fabricated by Taylor-Ulitovsky technique. By means of energy dispersive spectroscopy microanalysis, an average alloy composition of Cu56Ga28Mn16 was determined. The temperature dependence of magnetization measured at a low magnetic field showed the coexistence of two ferromagnetic phases. The Curie temperature of one phase is 125 K and above room temperature for the other one. X-ray diffraction at room temperature and at 100 K reflects the presence of the same three crystalline phases corresponding to the cubic B2 Cu-Mn-Ga structure as a main phase and the minor phases of fcc Cu rich solid solution with Mn and Ga and the monoclinic CuO.

Abstract: The discovery of the magnetoimpedance (MI) effect in 1994 had a strong impact on the development of magnetic sensors, offering miniature, highly sensitive, and quick response elements. Along with traditional areas of sensing applications (data storage, bio-medical electronics, robotics and security), the MI elements have a high potential for non-destructive testing (as eddy current probes) and smart sensory systems (self-sensing composites). In certain soft magnetic materials, such as composites of amorphous thin wires, the impedance change (MI ratio) can be as high as 600 % in the MHz band and 50-100% at GHz frequencies subjected to small magnetic fields or stresses. Furthermore, special thin-film structures have been proposed to improve the MI performance in miniature elements. This paper discusses physical concepts of MI in multilayered structures including MI ratio enhancement and effect of anisotropy, experimental results proving high sensitivity to the external stimuli for excitation frequencies up to few GHz, practical sensor designs and, finally, the use of MI fibers for tagging the composites to build-in sensing functionality .

Abstract: We report on tailoring magnetic properties and giant magneto-impedance GMI in glasscoated microwires fabricated by the Taylor-Ulitovsky method, by means of selection of their alloy composition and/or annealing conditions. Fe-rich microwires subjected to stress annealing show the hysteresis loops of inclined form due to induced transverse magnetic anisotropy, and hence become suitable for GMI. The transverse anisotropy depends on the annealing conditions: temperature, duration and stress. The application of external stress further drastically changes the shape of the hysteresis loops and the GMI spectra. The wires with compositions Co-Fe-Ni-Si-B and Co-Fe-Cr- Si-B are demonstrated to have a low Curie temperature (below 90oC) and pronounced temperaturedependent magnetic properties and GMI effect. Both families of developed microwires are foreseen for applications in high performance stress and temperature sensors as well as in tuneable sensory composite materials. Such composites contain short pieces of microwires embedded into a dielectric matrix and contribute to the effective ac permittivity. The latter depends on the wire magnetic properties through the GMI effect and can be tailored to produce a microwave response sensitive to environment: magnetic field, stress and temperature.

Abstract: Glass coated microwires with two metallic nucleus compositions Co57Fe 6.1Ni10B15.9Si11 and Fe36,4Co41,7B11,8Si10,1 with 3 different glass coating compositions (Pyrex – 74.5% SiO2, 15% - B2O3, 3%- Na2O, 2%- Al2O3 1.5% -K2O; Nonex – 73% SiO2, 16.5% - B2O3, 6% - PbO 3 %-Na2O, 1.5% -K2O; and F1 – 70.2% SiO2, 27% - B2O3, 0.8 %-Na2O, 2%- LiO2 1% -K2O;) with very similar geometry (metallic nucleus diameter 7 µm, total diameter 19 µm) have been successfully fabricated and studied. Ferich microwires in as-prepared state show rectangular hysteresis loops, which is connected with the strong internal stresses induced by the fabrication process. Co-rich compositions show inclined hysteresis loop with smaller value of coercive field. The coercivity, Hc, of Co-rich microwires is the highest and of Ferich samples is the lowest in the case of Pyrex coated microwires. The Nonex coated microwires are in the intermediate position while the F1 coated Co-rich microwires have the lowest Hc while the Fe-rich samples have the highest Hc. The mechanical tests show that the best tensile strain yield is observed in samples coated by Nonex glass followed by Pyrex and F1. In this way the variation of the glass coating material allows to tailor both magnetic and mechanical properties of glass coated tiny microwires.