DSpace Arşivi :: by Yazar "Atalay, S." değerine göre listeleniyor

Yazar "Atalay, S." seçeneğine göre listele

Listeleniyor 1 - 20 / 63

Amorphous ferromagnetic wire for manipulation of magnetic nanowires
(Elsevier Science Sa, 2015) Atalay, S.; Atalay, F. E.
The article reports the development of new type of magnetic tip to manipulate magnetic nanowires. The amorphous ferromagnetic tip has a composition of Fe77.5Si7.5B15. Electrochemical etching was performed at room temperature for various dc currents up to 5 mA. It was found that 4.4 mA etching current was the best tip formation current for the FeSiB wire. It was found that the tip radius is smaller than 200 nm after the etching process. Magnetic NiFe nanowires were manipulated using a 3D positioning system with the FeSiB tip. (C) 2015 Elsevier B.V. All rights reserved.
Asymmetric ?E Effect and its Use as a Magnetic Field Sensor
(Polish Acad Sciences Inst Physics, 2019) Atalay, S.; Kolat, V. S.; Izgi, T.
The Delta E effect was studied using Fe77B16Si5Cr2 amorphous ribbon, and asymmetry in the Delta E curves was created using micro magnets placed on the surface of the ribbon. Asymmetry was also observed in the vibration amplitude versus the magnetic field, and magnetization loops of amorphous ribbons with micro magnets were observed. The results show that the asymmetries in the Delta E curves and magnetisation loops are in agreement with each other. A linear change in vibration amplitude as a function of the applied magnetic field in the +/- 100 A/m region was observed, which is important for sensor applications.
Asymmetric giant magnetoimpedance effect created by micro magnets
(Elsevier Science Bv, 2018) Atalay, S.; Izgi, T.; Buznikov, N. A.; Kolat, V. S.
Asymmetric giant magnetoimpedance (AGMI) effect has been investigated in as-prepared and current annealed amorphous (Co0.9Fe0.05Ni0.05)(75)Si15B10 ribbons. Asymmetry was created by micro magnets. Different numbers of magnets were used and it was found that increasing number of magnet, the shift in AGMI curves increases. When two micro magnets were placed 1 cm away from the ends of ribbon, a distortion in two peak shape of the GMI curve was observed. At high frequency range, a linear change in the AGMI was observed for the current annealed sample. (C) 2018 Elsevier B.V. All rights reserved.
Characterisation of magnetic wires for fluxgate cores
(Elsevier Science Sa, 2008) Ripka, P.; Butta, M.; Malatek, M.; Atalay, S.; Atalay, F. E.
Orthogonal fluxgate sensors need only a single core and they can be made very small. We show how to measure properties of composite Cu/Py ferromagnetic wires to be used as cores for these sensors. Besides the well known axial loops we show how to measure the circumferential hysteresis loop and gating curves, which can directly be used for sensor modeling. It is generally believed that in composite wires the majority of the current flows through the copper core, thus reducing the possible perming effect of poorly magnetized core sections. We will show that this is true only at very low frequencies and for low magnetic layer thickness. The calculated values can be used as a starting point for FEM simulations. (c) 2007 Elsevier B.V All rights reserved.
Coil-less fluxgate effect in (Co0.94Fe0.06)72.5Si12.5B15 amorphous wires
(Elsevier Science Bv, 2010) Atalay, S.; Ripka, P.; Bayri, N.
In this study, the coil-less fluxgate properties of the as-cast and annealed amorphous wires with the composition (Co0.94Fe0.06)(72.5)Si12.5B15 were investigated. As its name implies, a coil-less fluxgate is a new type of magnetic-field sensor without a coil. When the wire is periodically saturated in a magnetic field in the circumferential direction with a 30 kHz, 62 mA driving current under a 16.5 pi rad/m torsional strain, there is a linear variation in the second harmonic of the voltage from the wire ends as a function of the applied external DC magnetic field along the length of the wire. Current-stress annealing of each sample improved the sensitivity of the coil-less fluxgate sensor. This is the first time that it has been shown that a linear change in the output of the coil-less fluxgate sensor. This is the first time that it has been shown that a linear change in the output of the coil-less fluxgate sensor can be obtained using torsion annealed wire without the necessity of twisting the wire during measurement. We showed that the linear operating range of the sensor can be increased by increasing the demagnetization factor in the sensing direction, so that the coil-less fluxgate sensor can be miniaturised just by reducing the wire length. (C) 2010 Elsevier B. V. All rights reserved.
Coil-less Fluxgate Effect in Amorphous Co71Fe1Mo1Mn4Si14B9 Ribbon
(Trans Tech Publications Ltd, 2012) Fidan, A.; Atalay, S.; Bayri, N.; Atalay, F. E.; Yagmur, V.
In this study, the coil-less fluxgate effect in Co71Fe1Mo1Mn4Si14B9 amorphous ribbon was investigated. The coil-less fluxgate is a new type of fluxgate sensor without a coil. It is based on helical anisotropy and deep circumferential magnetic saturation in the ferromagnetic fluxgate core. Coil-less fluxgate measurements were performed in as-cast and annealed ribbons at 480 mA current with 3, 12.5 and 25 rad/m torsion. The second harmonic of the output voltage detected from the ends of the wire show a linear variation in the low magnetic field region. The sensitivity of the current annealed ribbons in the presence of 25 rad/m torsion is about 570 V/T, which is comparable with previously reported fluxgate sensitivity values. The presented sensor has no coil so it is much easier to reduce the size of the sensor and easy to fabricate it.
Coil-less fluxgate effect in amorphous wires
(Elsevier Science Sa, 2010) Atalay, S.; Bayri, N.; Izgi, T.; Atalay, F. E.; Kolat, V. S.
In this study, the coil-less fluxgate properties of as-received amorphous microwires with the compositions (Co(0.94)Fe(0.06))(72.5)Si(12.5)B(15), Fe(77.5)Si(7.5)B(15) and Co(72.5)Si(12.5)B(15) have been investigated. As its name implies, a coil-less fluxgate is a new type of magnetic field sensor without a coil. When the (Co(0.94)Fe(0.06))(72.5)Si(12.5)B(15) wire is magnetically saturated in the circumferential direction with a 30 kHz and 48 mA driving current and under the effect of 33 pi rad/m torsional strain, there is a linear variation in the second harmonic of the voltage from wire ends, U(wire) as a function of the applied external dc magnetic field, H(z), along the wire length. The slope of the second harmonic versus H(z) curve changes in opposite directions as the direction of torsional strain changes from the positive to the negative direction. Coil-less fluxgate effects in as-received Fe(77.5)Si(7.5)B(15) and Co(72.5)Si(12.5)B(15) wires have also been investigated. A very small change in the second harmonic of voltage U(wire) is observed in Fe(77.5)Si(7.5)B(15) wire, with some small hysteresis. (C) 2010 Elsevier B.V. All rights reserved.
Coil-less fluxgate effect in CoNiFe/Cu wire electrodeposited under torsion
(Elsevier, 2011) Atalay, S.; Yagmur, V.; Atalay, F. E.; Bayri, N.
Co19Ni49.6Fe31.4 layer was electrodeposited onto a twisted Cu wire and helical anisotropy was induced in the magnetic Co19Ni49.6Fe31.4 shell. The magnetic and coil-less fluxgate (CF) properties are presented. The Co19Ni49.6Fe31.4/Cu wire, produced at zero torsional strain, shows a CF output of nearly zero. The samples produced under torsional strains of 29.5 pi and 59 pi rad/m show a linear change in CF output in the low-frequency range. At higher frequencies the CF output shows two linear ranges. A maximum sensitivity of 150V/T is observed at 20 kHz driving-current frequency and 67 mA driving current for a wire produced under 59 pi rad/m torsional strain. It is also found that the slope of the CF curve depends on the direction of induced anisotropy. (C) 2011 Elsevier B.V. All rights reserved.
Coil-Less Fluxgate Effect in Negatively Magnetostrictive Co72.5Si12.5B15 Amorphous Wire
(Amer Scientific Publishers, 2013) Atalay, S.; Bayri, N.; Fidan, A.; Yagmur, V.; Izgi, T.; Atalay, F. E.; Kolat, V. S.
In this study, we have investigated coil-less fluxgate (CF) properties of as-cast and annealed Co72.5Si12.5.B15 amorphous wire. As-cast wire without any torsional strain shows nearly zero output in the second harmonic. When the as-cast wire is twisted a linear variation in the second harmonic of output was obtained as a function of applied magnetic field. It was also shown that a linear change in the output of the coil-less fluxgate sensor can be obtained using torsion annealed wire without twisting the wire during measurement. The second harmonic of U-wire showed a linear dependence at magnetic fields of +/- 400 A/m and the sensitivity of the sensor at 50 kHz frequency is about 75 V/T at 61 mA ac driving-current frequency for the wire annealed at 525 mA dc current for 20 minutes at 500 MPa tensile stress and 33 pi rad/m torsional strain.
Crack Detection Using Fluxgate Magnetic Field Sensor
(Polish Acad Sciences Inst Physics, 2014) Izgi, T.; Goktepe, M.; Bayri, N.; Kolat, V. S.; Atalay, S.
In this study, the variation of the magnetic flux distribution in a magnetised ferromagnetic material which has in homogeneity as a crack is studied. An orthogonal fluxgate magnetic field sensor was used in the inspection of cracks. In the fluxgate sensor, the sensing element (Co(0.94)Fec(0.06))(72.5)Si2.5B15 amorphous ferromagnetic wire was placed inside a pickup coil winding with 50 mu m copper wire and connected to a signal generator and the output from pick-up coil was detected using a lock-in amplifier. The surface profile of magnetic materials with a crack was obtained using a specially designed 3-dimensional moving system. A large decrease in the output voltage of the sensor was observed when the sensor was moved on the top of the crack, after the further movement of the sensor the output voltage came back to the previous value.
Crystallisation Kinetics of Co75-xMxSi15B10 (M = Fe, Mn, Cr and x=0, 5) Amorphous Alloys
(Polish Acad Sciences Inst Physics, 2016) Bayri, N.; Kolat, V. S.; Izgi, T.; Atalay, S.; Gencer, H.; Sovak, P.
In this study, the effect of Fe, Mn and Cr substitution for Co on the crystallization kinetics of amorphous Co75-xMxSi15B10 (M = Fe, Mn and Cr; x = 0 and 5) alloys were investigated. The broad diffraction peaks in the X-ray diffraction patterns for as-quenched ribbons indicated that all of the samples exhibit an amorphous structure. The activation energies of the alloys were calculated from differential thermal analysis data using the Kissinger, Ozawa and Augis-Bennett models. The increased activation energy for Fe, Mn and Cr doped samples indicated that the thermal stability and the crystallization kinetics were improved in the doped samples. The value of the Avrami exponent indicated that the crystallization is typical diffusion controlled three-dimensional growth for all of the samples.
The crystallisation kinetics, magnetic and magnetocaloric properties of Gd55Co20Fe5Al20 - xSix (x=0, 5, 10, 15) alloys
(Elsevier, 2013) Gencer, H.; Izgi, T.; Kolat, V. S.; Bayri, N.; Kaya, A. O.; Atalay, S.
The effects of substituting Si for Al on the crystallisation kinetics and magnetic and magnetocaloric properties of Gd55Co20Fe5Al20 Si-- x(x) (x = 0, 5, 10, 15) alloys have been investigated in detail. The broad diffraction peaks in the XRD patterns indicated that all the samples have amorphous structures. The activation energies of the alloys were calculated using the Kissinger, Ozawa and Augis-Bennett models based on differential thermal analysis data. The Avrami exponent n was calculated from the Johnson-Mehl-Avrami equation. The increase in the activation energy as the Si content increased to x = 10 indicated that the addition of Si improves the thermal stability and slows the crystallisation kinetics of the samples. The value of the Avrami exponent showed that the nucleation and growth mechanisms of the crystallisation process depend on the Si concentration. The maximum entropy change reached a maximum value of 6.82 J/kg K for x = 5 and then decreased with further increases of Si. The refrigeration capacities are 558, 665,700 and 519 J/kg for x = 0, 5, 10 and 15, respectively. The increased thermal stabilities and large refrigeration capacities make these amorphous alloys attractive candidates for magnetic refrigeration applications. (C) 2013 Elsevier B.V. All rights reserved.
Crystallization kinetics of Fe73.5-xMnxCu1Nb3Si13.5B9 (x=0, 1, 3, 5, 7) amorphous alloys
(Elsevier Science Bv, 2009) Bayri, N.; Izgi, T.; Gencer, H.; Sovak, P.; Gunes, M.; Atalay, S.
In this study, we have investigated the effect of substituting Mn for Fe on the crystallization kinetics of amorphous Fe73.5-xMnxCu1Nb3Si13.5B9 (x = 1, 3, 5, 7) alloys. The samples were annealed at 550 degrees C and 600 degrees C for 1 h under an argon atmosphere. The X-ray diffraction analyses showed only a crystalline peak belonging to the alpha-Fe(Si) phase, with the grain size ranging from 12.2 nm for x = 0 to 16.7 nm for x = 7. The activation energies of the alloys were calculated using Kissinger, Ozawa and Augis-Bennett models based on differential thermal analysis data. The Avrami exponent n was calculated from the Johnson-Mehl-Avrami equation. The activation energy increased up to x = 3. then decreased with increasing Mn content. The values of the Avrami exponent showed that the crystallization is typical diffusion-controlled three-dimensional growth at a constant nucleation rate. (C) 2008 Elsevier B.V. All rights reserved.
The Dynamic Effects in Electrodeposited NiFe/Cu Wire with Preliminary Torsion
(Trans Tech Publications Ltd, 2012) Yagmur, V.; Atalay, F. E.; Bayri, N.; Atalay, S.
Ni80Fe20/Cu composite wires were produced under torsion using electrodeposition method. The total length of the magnetic film deposited onto 50 mu m Cu wire is 3 cm and the thickness of the magnetic layer is about 10 gm. All samples showed single peak in magnetoimpedance (MI) curves. The magnitude (Delta Z/Z) % are 260%, 235% and 119% for samples produced under 22.4, 44.8, 89.7 rad/m torsion values, respectively at driving frequency of 160 kHz. MI effect magnitude decreases with increasing applied torsion during the electrodeposition process. A linear change in the second harmonics of output voltage from wire ends as a function of applied magnetic field (coil-less fluxgate effect) was observed in all sample. The sensitivity of coil-less output increases with increasing torsion and maximum sensitivity was observed in the sample produced at 89.7 rad/m torsion.
The effect of back electrode on the formation of electrodeposited CoNiFe magnetic nanotubes and nanowires
(Elsevier Science Bv, 2010) Atalay, F. E.; Kaya, H.; Yagmur, V.; Tari, S.; Atalay, S.; Avsar, D.
The electrodeposition of cobalt + nickel + iron alloy nanostructures in aqueous sulfate solution has been studied using vitreous templates placed on highly ordered porous anodic alumina oxide (AAO). During the deposition process some electrochemical bath parameters such as ion content, deposition voltage, pH and temperature of solution were kept constant. The morphological properties of the nanostructures were studied by scanning electron microscopy (SEM) and the chemical composition was determined by examination of the energy dispersive X-ray (EDX) spectra. The magnetic behaviour of the arrays was determined with a vibrating sample magnetometer (VSM). Voltammetric and galvanostatic results indicate that the back electrodes placed on AAO plays the main role in obtaining nanowire or nanotube structured material. (C) 2009 Elsevier B. V. All rights reserved.
Effect of Fe Substitution on Magnetic and Magnetocaloric Properties of La0.94Bi0.06Mn1-xFexO3 (x=0, 0.05, 0.075 and 0.1) Compounds
(Korean Magnetics Soc, 2017) Gencer, H.; Kolat, V. S.; Bayri, N.; Izgi, T.; Atalay, S.
The effects of Fe doping on structural, magnetic and magnetocaloric properties of La0.94Bi0.06Mn1-xFexO3 (x = 0, 0.05, 0.075, 0.1) compounds were investigated. X-ray analyses showed that the substitution of Mn by Fe produced no major structural change. It was found that the saturation magnetization, Curie temperature and maximum value of magnetic entropy change decrease with increasing Fe content. The decrease in magnetic entropy change was attributed to the decrease in saturation magnetization and the nature of phase transition transforms from first-order to second-order. The refrigeration capacities were determined to be 259 and 230 J/kg for the x = 0 and 0.075 samples, respectively at a field change of 5 T.
Effect of tensile stress on magnetoimpedance properties of CoNiFe/Cu wire
(Iop Publishing Ltd, 2009) Bayri, N.; Kolat, V. S.; Kaya, H.; Atalay, F. E.; Izgi, T.; Atalay, S.
A Co20.5Ni40.5Fe39 magnetic film was electrodeposited onto a copper wire 50 mu m in diameter. The magnetoimpedance (MI) effect, (Delta Z/Z)(H)(%) = ((Z(H)-Z(max))/Z(max)) x 100, was measured in the Co20.5Ni40.5Fe39/Cu composite wire under varying tensile stresses up to 30 MPa. The results showed that large MI and stress impedance (SI) effects can be observed in the Co20.5Ni40.5Fe39/Cu composite wire. The MI curve at zero tensile stress shows a small split peak in the low-field region. With increasing applied tensile stress, single-peak behaviour of the MI effect is observed. The magnitude of the MI and SI effects decreases with increasing tensile stress, sigma. The peak values of (Delta Z/Z)(H)(%) for the sample decrease from 265% at sigma = 0 to 39% at sigma = 30MPa at 40 kHz ac driving-current frequency. The impedance of a sample under the effect of 25 MPa tensile stress at 40 kHz ac driving-current frequency showed variations of about 146%. It was also found that the frequency value, f*, where the maximum MI effect was observed as a function of driving-current frequency, increases with increasing tensile stress.
Effects of Ru substitution on the structural, magnetic and magnetocaloric properties of Pr0.68Ca0.22Sr0.1Mn1-xRuxO3(x=0, 0.05, 0.1 and 0.2) compounds
(Springer, 2020) Pektas, M.; Izgi, T.; Gencer, H.; Atalay, S.; Kolat, V. S.; Bayri, N.
The structural, magnetic and magnetocaloric properties of polycrystalline Pr0.68Ca0.22Sr0.1Mn1-xRuxO3(x = 0, 0.05, 0.1 and 0.2) compounds were studied. All the samples crystallized in an orthorhombic symmetry. A significant increase in the lattice parameters in the doped samples was attributed to the existence of Ru with a the mixed-valence state (Ru3+/Ru4+). The increase in the Curie temperature (T-c) with increasing Ru content was interpreted as Ru doping promoting the ferromagnetic interactions between Ru4+-Mn(3+)and Ru4+-Mn(4+)pairs. The decrease in saturation magnetisation was attributed to an AFM interaction between the Ru3+-Mn(3+)and Ru3+-Mn(4+)pairs and smaller magnetic moments of Ru than those of Mn. The decrease in |Delta S-M| (from 4.66 J kg(-1) K(-1)forx = 0.05 to 2.32 J kg(-1) K(-1)forx = 0.2 at 5 T) was attributed to the nature of phase transition (from a first-order to second-order transition) and a decrease in the saturation magnetisation.
Electrical Transport and Magnetoresistance of La0.67Ca0.33MnO3: Agx (x=0, 0.1, 0.2, 0.3, 0.4) Composites
(Korean Magnetics Soc, 2012) Gencer, H.; Pektas, M.; Babur, Y.; Kolat, V. S.; Izgi, T.; Atalay, S.
The structural, magnetic and magnetotransport properties of La0.67Ca0.33MnO3: Ag-x (x = 0, 0.1, 0.2, 0.3 and 0.4) composites were investigated systematically. X-ray and EDX analysis indicated that Ag is not substituted into the main La0.67Ca0.33MnO3 phase and remains an additive to the second phase at the grain boundary. The Curie temperature first decreased from 269 K for x = 0 to 257 K for x = 0.1 and then remained nearly unchanged with increasing Ag content. For the x > 0.1 samples, a second transition temperature (T-M12) was observed in the resistance curves. At temperatures below 150 K, a significant enhancement in MR was observed while high temperature MR decreased with increasing Ag content. The maximum MR was observed to be 55% in the x = 0.4 sample at 10 K and a 6T magnetic field, this value is larger than that of pure La0.67Ca0.33MnO3 (53% at 265 K and 6 T). In addition, at low fields (H < 1T), a sharp increase in the MR was observed.
Electrical transport and magnetoresistance properties of La0.67Ca0.33Mno3 film coated on pyrex glass substrate
(World Scientific Publ Co Pte Ltd, 2008) Gencer, H.; Goktas, A.; Gunes, M.; Mutlu, H. I.; Atalay, S.
The electrical transport and magnetoresistance properties of the polycrystalline La0.67Ca0.33MnO3 film produced on a Pyrex substrate were investigated for the first time. X-ray powder diffraction indicated that the film sample has a perovskite structure. Scanning electron microscope indicated that La0.67Ca0.33MnO3 film thickness is approximately 500 nm, and the average grain size of this sample varies between 40 and 50 nm. La0.67Ca0.33MnO3 film showed a phase transition from paramagnetic to ferromagnetic at (T-C) 80 K and a metal insulator transition at (T-MI) 77.5 K and at 2 mT magnetic field. The upturn of the resistance observed at low temperatures (<36 K) was attributed to the Coulomb blockade, and the strong structural disorder is due to the large lattice mismatch and strain relaxation. A large magnetoresistance ratio [MR %] of 780% was observed at 100 K and 6 T magnetic field.

Yazar "Atalay, S." seçeneğine göre listele

Sayfa Başına Sonuç

Sıralama seçenekleri