Yazar "Aksan, M. Ali" seçeneğine göre listele

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    Electrical Properites of Superconducting Cross - (nano) Whiskers Junction
    (Tubitak Scientific & Technological Research Council Turkey, 2005) Altin, Serdar; Yakinci, Eyuphan; Balci, Yakup; Aksan, M. Ali
    Bi-2212 superconducting single crystal (nano) whiskers have been fabricated by annealing a melt-quenched (glass) Bi3Sr2Ca2Cu3Ox precursor. A couple of (nano) Whiskers obtained were placed crosswise on a YSZ single crystal substrate and then heat treated at 830 C for 25 minute to form nano-scale junction. The T-c of each nano-whisker was found to be 85 K and the critical current density, J(c), of the whiskers was calculated to be 1177 Acm(-2) at zero field. The I - V characteristics of the nano-junction at 30 K were found to show a multiple-branch structure, which is the main behavior of the Josephson junction.
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    Electrical properties of superconducting cross-(nano) Whiskers junction
    (Turkish Journal of Physics, 2005) Altın, Serdar; Yakıncı, Eyüphan; Balcı, Yakup; Aksan, M. Ali
    Abstract: Bi-2212 superconducting single crystal (nano) whiskers have been fabricated by annealing a melt-quenched (glass) Bi3Sr2Ca2Cu3Ox precursor. A couple of (nano) Whiskers obtained were placed crosswise on a YSZ single crystal substrate and then heat treated at 830 C for 25 minute to form nano-scale junction. The Tc of each nano-whisker was found to be 85 K and the critical current density, Jc, of the whiskers was calculated to be 1177 Acm?2 at zero field. The I —V characteristics of the nano-junction at 30 K were found to show a multiple-branch structure, which is the main behavior of the Josephson junction.
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    Improved superconducting properties of MgB2 thin films fabricated by ultrasonic spray pyrolysis method at high temperature
    (Elsevier Sci Ltd, 2012) Yakinci, M. Eyyuphan; Yakinci, Z. Deniz; Aksan, M. Ali; Balci, Yakup
    High quality MgB2 superconducting thin films have been successfully prepared by 2.4 MHz ultrasonic spray pyrolysis (USP) system on single crystal Al2O3 (001) substrates. The microstructure, electrical and magnetic properties of approximately 500-600 nm thick films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) in conjunction with the energy dispersive X-ray analysis (EDX), resistance versus temperature (R-T) and magnetization measurements (M-H) under different magnetic fields and transport critical current density (J(c)). Films were first heat treated in situ in the spraying chamber with an extra Mg powder during deposition to compensate excess evaporation of Mg from the films and then additionally heat treated in Ar atmosphere at 700 degrees C for a short time. According to the results obtained, orientation on any particular direction for the crystal growth was not seen. Homogeneous, highly dense and highly smooth surface morphology and low resistance have been achieved under optimum conditions. Optimally treated films exhibited relatively high transport critical current density of 2.37 x 10(5) A cm(-2). These results have been also compared with the J(c)(mag) results calculated from the M-H curves. The electrical resistance property of the best samples was obtained to be 39.5 and 37.4 K for T-c and T-zero, respectively. (C) 2012 Elsevier Ltd. All rights reserved.
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    Magnetocaloric Properties of Ni-Rich Ni50-xCoxMn38Sn12B3 Shape Memory Ribbons
    (Springer, 2021) Kirat, Gokhan; Kizalaslan, Olcay; Aksan, M. Ali
    The present study presents the magnetocaloric effect (MCE) properties of Ni-rich Ni50-xCoxMn38Sn12B3 (x = 0, 1, 3, 5) ribbons during both heating and cooling processes. The Co substitution caused an increase of magnetization difference Delta M and hence an improvement of the MCE. An inverse giant magnetocaloric effect (IMCE) and a high effective refrigerant capacity RCeff were observed in the x = 3 ribbons. A high amount of Co (x = 5) content led to an inverse magnetic entropy Delta S-M peak with a wide temperature range. Magnetostructural coupling over a wide temperature range is of great importance for technological purposes. On the other hand, the MCE properties were thermal hysteresis dependent, which has to be considered in the technological applications.
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    Magnetocaloric Properties of Ni-Rich Ni50-xCoxMn38Sn12B3 Shape Memory Ribbons (vol 34, pg 581, 2021)
    (Springer, 2021) Kirat, Gokhan; Kizilaslan, Olcay; Aksan, M. Ali
    [Abstract Not Available]
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    Magnetoresistance properties of magnetic Ni-Mn-Sn-B shape memory ribbons and magnetic field sensor aspects operating at room temperature
    (Elsevier Science Bv, 2019) Kirat, Gokhan; Kizilaslan, Olcay; Aksan, M. Ali
    In this study, the magnetotransport properties of the Ni48.95Mn37.74Sn13.32B3 ribbons prepared by melt-spinning technique were investigated in details. The martensitic-austenite phase transition was obtained between 280 K and 285 K which are near the room temperature. From rho-H measurements, it was found that an anomalous Hall effect at 281, 283 and 285 K between M-s (martensite start temperature) and M-f (martensite finish temperature) temperatures is domianant mechanism. It was seen that a voltage variation of 5 mu V (between 0 and 10 kOe) at a constant current of 1 mA is one of the best values found for the Heusler alloys. The rho-H results revealed that the ribbons showed the magnetic field-induced one-way shape memory effect (SME). High voltage change caused by magnetoresistance was reached at a constant current of 100 mA at 298 K. The results suggest that the Ni-Mn-Sn-B ribbon is a potential candidate to prepare a magnetic field sensor operating at the room temperature.
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    Süperiletken materyallerde tanecik yöneliminin "x ışınları Pole-Figure" yöntemi ile incelenmesi
    (2005) Yakıncı, M.Eyyüphan; Balcı, Yakup; Aksan, M. Ali; Alagöz, Serkan
    [Abstract Not Available]
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    Thermoelectric power and thermal conduction studies on the Nd substituted BPSCCO (2234) superconductors
    (Elsevier, 2007) Ozkurt, Berdan; Ocelik, Bekir; Kiymac, Kerim; Aksan, M. Ali; Yakinci, M. Eyyuephan
    In this study, we have carried out thermoelectric power (S-T) and thermal conductivity (kappa-T) measurements from room temperature down to 15 K on Bi1.7Pb0.3-xNdxSr2Ca3Cu4O12+y samples, where 0.0 <= x <= 0.1. The thermoelectric powers, S(T), of the samples have both negative (at high T) and positive values (at low T), and are found to increase with decreasing temperature, reaching maxima (peaks) around their T, values and to drop rapidly to zero below T,. The magnitude of the peaks decreases with increasing Nd-content. The results obtained have been analyzed in terms of the two-band model with linear T-term and Xin's two-band model. A very good agreement between the first model and our thermoelectric power data is obtained, but the fit to the second model is poor. The fittings to the models indicate that while the electrons are effective at higher temperatures, the holes become dominant at lower temperatures, the number of holes and the Fermi energies decrease with increasing Nd-content. Nd substitution also has a considerable effect on the thermal conductivity, kappa. A broad maximum is obtained on kappa versus T plot, just below the T, value of each sample. However, the peaks decrease in intensity and also broaden with increasing Nd concentration. This behavior is believed to be due to the scattering of the carriers. (c) 2007 Elsevier B.V. All rights reserved.