Yazar "Baglayan, O." seçeneğine göre listele

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    Electrochemical effects and magnetic properties of B substituted LiCoO2: Improving Li-battery performance
    (Elsevier Science Sa, 2016) Oz, E.; Altin, S.; Demirel, S.; Bayri, A.; Altin, E.; Baglayan, O.; Avci, S.
    LiCo(1-x)BxO(2) (x = 0, 0.125, 0.25, 0.375, 0.5, 0.75 and 1) samples were synthesized via solid state reactions. They were characterized by SEM, X-ray powder diffraction, FTIR, Raman, electrical and magnetic measurements. XRD data show impurity phases for x >= 0.25 samples due to boron content. Based on FTIR studies, the peak position of CoO6 shifts with increasing B content. The Raman spectra of LiCoO2 shows the presence of three broad bands, indicating the possible formation of spinel structure. The effective magnetic moments of the samples were calculated using Curie-Weiss law with temperature independent term. The M-H curves of x = 0.375 and 0.5 samples show very weak hysteresis loops. Effects of boron substitution on battery performance are also investigated. x = 0.125 and x >= 0.25 samples give promising results due to their enhanced reversibility of cycling compared to pristine LiCoO2. Capacity retentions for 100 cycles for x = 0, 0.125 and 0.25 samples are 22%, 81% and 83%, respectively. (C) 2015 Elsevier B.V. All rights reserved.
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    Fabrication of Ca-Mn-Nb-O compounds and their structural, electrical, magnetic and thermoelectric properties
    (Iop Publishing Ltd, 2018) Oz, E.; Demirel, S.; Altin, S.; Altin, E.; Baglayan, O.; Bayri, A.; Avci, S.
    CaMn1-xNbxO3-delta (0 <= x <= 1) were synthesized by conventional solid state reaction method. The structural properties were determined by FTIR, Raman, XRD, XAS measurements. The FTIR and Raman modes change by increasing Nb content and the lattice volume increases by increasing Nb content. The solubility limit of Nb is determined as x <= 0.3 and impurity phases start to appear above this limit. The temperature dependence of the magnetization data shows an antiferromagnetic transition below 120 K for low Nb content. Increasing the Nb content causes a change in the magnetic phase from antiferromagnetic to paramagnetic. The oxygen deficiency in CaMnO3-delta may cause the formation of polaron effect which is destroyed by the Nb ions. The difference graph of XAS data for x = 0 and 0.5 show that the number of Mn3+ ions increases by increasing Nb content to maintain the charge neutrality.
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    New Cu-Al Based Quaternary and Quinary High Temperature Shape Memory Alloy Composition Systems
    (Amer Inst Physics, 2018) Karaduman, O.; Ozkul, I.; Altin, S.; Altin, E.; Baglayan, O.; Canbay, C. Aksu
    The Cu-rich HTSMAs (high temperature shape memory alloys) with new compositions of a quaternary Cu24.07Al- 1.85Ti-1.40Co (at%) and a quinary Cu-24.08Al-2.23Fe-1.34Co-0.97Ti (at%) were fabricated by arc melting and analysed by differential thermal analysis (DTA), X-ray and optical microscopy measurements to find out the thermal and structural properties of the alloys. During thermal measurements, the alloy samples exhibited very well characteristic hysteresis curves of martensitic transformations at high temperatures far above 200 degrees C and their characteristic martensite and austenite phase transition temperatures and kinetic parameters such as enthalpy, entropy and equilibrium temperatures were calculated. The structural X-ray diffraction lattice planes and metallographic semblances on the surface morphology of the crystal natured alloy samples were determined and these results indicated the martensite forms at room temperature. In conclusion, deploying of these new composed alloys in miscellaneous HTSMA applications may be viable.
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    Structural, magnetic, electrical and electrochemical properties of SrCo02.5, Sr9Co2Mn5O21 and SrMnO3 compounds
    (Elsevier Sci Ltd, 2017) Demirel, S.; Oz, E.; Altin, S.; Bayri, A.; Baglayan, O.; Altin, E.; Avci, S.
    SrCo1-xMnxO3-d (0 <= x <= 1) were synthesized by conventional solid state reaction method. We found that Mn substitution hinders the decomposition of carbonate at 900 degrees C and increases the synthesis temperature of SrCo1-xMnxO3-d to 1200 degrees C. Three different main phases emerge as the Mn content is increased; SrCoO2.5, Sr9Co2Mn5O21 and SrMnO3. Structural properties of the samples were investigated by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, x-ray diffraction (XRD) and scanning electron microscopy (SEM). Valance states of the transition metal (TM) ions were estimated based on lattice parameters and ionic radii of TM ions. High temperature resistivity measurements show hysteresis upon heating and cooling and is attributed to oxygen release without any endothermic/exothermic activity. The spin configurations of Co and Mn ions in SrCoO2.5, Sr9Co2Mn5O21. and SrMnO3 were estimated by Curie-Weiss fitting of X-T curves. Electrochemical measurements show two anodic/cathodic peaks indicating two main types of oxygen sites in the unit cell.