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Öğe The effect of furnace annealing and surface crystallization on the anisotropy, ?E and magnetoimpedance effects in Fe71Cr7Si9B13 amorphous wires(Iop Publishing Ltd, 2004) Bayri, N; Kolat, VS; Atalay, FE; Atalay, SThe dependence of the magnetization loops, coercivity, anisotropy constant, DeltaE and magnetoimpedance (MI) effects in positively magnetostrictive Fe71Cr7Si9B13 amorphous wires on annealing conditions were studied. Samples were annealed at temperatures of 440degreesC and 460degreesC for durations between 0.3 and 300 min. The results indicate that progressive annealing first leads to relief of internal stresses and annealing of wires at 460degreesC for 60 min produces the minimum coercivity of about 1 A m(-1). Further annealing increases the coercivity and anisotropy, due to partial crystallization at the surface. It was found that the anisotropy changes its direction to the circumferential direction with the surface crystallization. The maximum change in Young's modulus was measured to be about 75% in a partly surface crystalline sample. It was observed that the magnitude of the MI effect of the stress relieved sample could exceed 200% at 1 MHz.Öğe Effect of hydrogen charging on the electrochemical and magnetic properties of Fe73.5M1Nb3Si13.5B9 (M = Cu, Pt, Pd, Ag, Mn) alloys(Wiley-V C H Verlag Gmbh, 2002) Kolat, VS; Turkdemir, H; Adigüzel, HI; Atalay, FE; Atalay, S; Sovak, PThe effects of hydrogen absorption on the electrochemical, magnetic and magnetoelastic properties of amorphous Fe73.5M1Nb3Si13.5B9 alloys (M = Cu, Pt, Ag, Pd, Mn) were investigated. Hydrogen was charged cathodically for 30 min with cathodic current density of 50 A/m(2) in all samples using 0.5 M H2SO4 solution with 0.1 g/l As2O3 as a poison. It was observed that the partial substitution of Pt. Mn, Ag, Pd for Cu in Fe73.5Cu1Nb3Si13.5B9 has a great influence in the hydrogen absorption properties.Öğe The effect of nickel electrodeposition on magnetic properties of CoFeSiB amorphous wire(Elsevier Science Bv, 2004) Atalay, FENickel films were electrodeposited on rapidly quenched amorphous wires from nitrate bath using a constant voltage. It was found that the pH of plating bath had a very strong effect on the formation of nickel films. The magnetic field, H, dependence of the impedance, of nickel plated (Co0.94Fe0.06)(72.5)Si12.5B15 wires have been investigated using a Hewlett-Packard 4294A impedance analyser with 42941A impedance probe. The best elecroplating condition and GMI response were obtained for the plated wire at pH 5 for 30 min plating time. (C) 2003 Elsevier B.V. All rights reserved.Öğe Effect of pH on the magnetoimpedance properties of electrodeposited CoNiFe microtubes(Elsevier Science Bv, 2006) Atalay, FE; Kaya, H; Atalay, SCobalt/nickel/iron (CoNiFe) magnetic samples were prepared by electrodeposition onto copper wires with a diameter of 50 pin. The magnetic properties of CoNiFe microtubes were systematically investigated at pH 2-3.5. It was observed that the composition, surface quality and magnetic and magnetoimpedance (MI) properties of the CoNiFe magnetic tubes were strongly affected by the pH of the electrochemical bath. The MI ratio of 123.2% at 160 kHz and a coercivity of 51.5 A/m were obtained for the sample that was produced in the pH 2.4 solution. The energy dispersive X-ray spectrum was also evaluated; this film had a composition of 22.14% Co. 59.94% Ni and 17.92% Fe, with no impurities. (c) 2005 Published by Elsevier B.V.Öğe Giant magnetoimpedance effect in NiFe/Cu plated wire with various plating thicknesses(Elsevier Science Sa, 2005) Atalay, FE; Atalay, SIn this study, the magnetoimpedance, MI, effect in NiFe/Cu wire with various plated NiFe thicknesses was investigated. The MI results showed that the frequency, where the maximum MI occurs, decreases with increasing plating thickness. During the plating process some parameters such as the plating voltage, pH, and the temperature of solutions were kept constant. It was found that the thickness of the plated NiFe layer changes with plating time and the obtained plated layers are approximately 1-2, 3.5 and 10 mu m for 10, 60 and 180 min plating times, respectively. It was found that the NiFe film thickness had a significant effect on the magnitude and frequency dependence of the MI effect. The magnitude of the MI ratio under the H = 7400 A/m can reach about 750% for 180 min plating at 55 kHz driving current frequency. (c) 2004 Elsevier B.V. All rights reserved.Öğe Magnetoimpedance effect in electrochemically etched CoFeSiB amorphous wires(Elsevier Science Bv, 2005) Atalay, FE; Atalay, S; Kaya, H; Bahadir, ARAs-received CoFeSiB amorphous wires with 128 mu m diameter were electrochemically etched at constant voltage to obtain micro magnetoimpedance (MI) sensor. Wires with different diameters from 13 to 100 mu m were obtained at various constant voltage and pH conditions. The diameters and surface properties of the wires were studied by scanning electron microscopy. It was found that the magnitude of the magnetoimpedance effect was first increased and then decreased with decreasing wire diameter. The thinnest wire obtained at pH 4 and 0.4 V, has a diameter of 13 mu m and this wire shows a 4.95% variation in the magnitude of (Delta Z/Z)(%). The results were discussed On the basis of internal stress distribution and a simple magnetic moment rotational model. (c) 2005 Elsevier B.V. All rights reserved.Öğe Magnetoimpedance effect in electroplated NiFeRu/Cu wire(Iop Publishing Ltd, 2006) Atalay, FE; Kaya, H; Atalay, SMagnetoimpedance (MI) and hysteresis loops were studied in electroplated Ni-79.1 Fe-20.9/Cu, Ni75.64Fe24.26Ru0.10/Cu, Ni79.51Fe20.31Ru0.18/Cu and Ni75.99Fe23.66Ru0.34/Cu wires. Scanning electron micrographs showed that crack-free electroplated wires were obtained with a smooth surface. The average grain size varied between 3 and 10 mu m for all samples. It was found that circumferential anisotropy was induced in all samples during the electroplating process. The maximum MI response was 459 % at a frequency of 90 kHz, 361 % at 110 kHz, 157 % at 100 kHz and 114 % at 340 kHz for Ni79.1Fe20.9/Cu, Ni75.64Fe24.26Ru0.10/Cu, Ni79.51Fe20.31Ru0.18/Cu and Ni75.99Fe23.66Ru0.34/Cu wires, respectively.Öğe A position sensor based on magneto-impedance effect(Wiley-V C H Verlag Gmbh, 2002) Atalay, FE; Atalay, SAn alternative measurement method for the giant magneto-impedance effect is presented in this study. The method measures pulse width instead of induced voltage between the ends of an amorphous wire as a function of external dc magnetic field. Amorphous magnetic wire with (Co0.94Fe0.06)(72.5)Si12.5B15 composition was used in this study. In the position sensing measurements, a small permanent magnet is brought near the wire and the pulse width response is measured as a function of distance between the permanent magnet and the amorphous as-received wire. The advantages of the alternative measurement method for the giant magneto-impedance effect for position detection are also discussed.Öğe Symmetry and bonding interactions in [Cu2Cl6]- complexes(Wiley-V C H Verlag Gmbh, 2002) Atalay, FETwo kinds of magnetic interactions are experimentally reported in [Cu2CI6](-) complexes, namely ferromagnetic and antiferromagnetic ones. Symmetry related magnetic interactions in these complexes have been considered. First we defined the local symmetry properties of the molecule and then we determined symmetry adapted molecular orbitals. The bonding orbitals among two Cu atoms in [Cu2Cl6](-) complexes seem to be sigma orbitals. However, the structure of these molecules indicates that a bonds must exist in these molecules.Öğe Torsional stress impedance effect in Fe71Cr7Si9B13 amorphous wire(Wiley-V C H Verlag Gmbh, 2004) Atalay, FE; Bayri, N; Bahadir, AR; Atalay, SThe magnetoimpedance effect has been measured in as-received and current annealed Fe71Cr7Si9B13 amorphous wires under torsional stress varied up to 1.2 rad/cm. It was found that the torsional stress dependence of impedance of as-received amorphous wire has a non-monotonous shape with first an increase of the impedance and then a decrease. On the other hand, the impedance of current annealed wire directly starts to decrease with increasing torsional stress. The current annealing of wire results in a large variation in the magnitude of torsional stress impedance effect, (DeltaZ/Z)xi(%), up to 150%. Also, a simple mathematical model based on the magnetic moment rotation to explain torsional stress versus impedance data was developed and the results were partly discussed on the basis of this model.
