Browsing by Author "Çipiloǧlu M.A."

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    Effects of thermal oxidation temperature on vacuum evaporated tin dioxide film
    (2012) Çakmak H.M.; Çetinkara H.A.; Kahraman S.; Bayansal F.; Tepe M.; Güder H.S.; Çipiloǧlu M.A.
    In order to investigate the effect of thermal oxidation temperature on tin dioxide (SnO 2), tin dioxide films were obtained on quartz substrates by vacuum evaporation of tin metal. The films were characterized by X-ray diffraction (XRD) analyses, scanning electron microscopy (SEM), temperature dependent electrical resistivity measurement and optical absorption spectroscopy. The SEM images showed that the films are dense, continuous and are composed of nanoparticles and particle sizes are increased after thermal oxidation. From the X-ray measurement results, the films indicated two strong reflection peaks of tetragonal structure in the orientations of (1 0 1) and (2 0 0) at 2θ = 33.89°and 37.95°, respectively. Intensity of the peaks increased with increasing thermal oxidation temperature. We found resistivity values of about 10 -4 Ω-cm. Optical absorption spectra of the films in the UV-Vis spectral range revealed that optical band gap (E g) value of the films increases with increasing thermal oxidation temperature. © 2012 Elsevier Ltd. All rights reserved.
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    Theoretical investigation on molecular structure and electronic properties of BxLiycluster for lithium-ion batteries with quantum ESPRESSO program
    (MDPI AG, 2020) Çipiloǧlu M.A.; Özkurt A.
    In this study, molecular structure and electronic properties of eleven BxLiy (x = 1-3, y = 1-3) clusters are examined using the Perdew, Burke and Ernezerhof (PBE) method in the Quantum ESPRESSO program. Three main groups, consisting of two atoms, three atoms and four atoms, are selected as the starting points. The stable configurations, their binding energies per atom (Eb), dissociation energy (AE), and the second difference in energy (A2E), HOMO-LUMO (HOMO: Highest Occupied Molecular Orbital LUMO: Lowest Occupied Molecular Orbital) gaps, total energy, frequency, force on atom, point group, bond length, density of state (DOS) and band structures are investigated for BxLiy (x = 1-3, y = 1-3) clusters. The results of binding energies (Eb), dissociation energy (AE) and the second difference in energy (A2E) show that BLi, BLi2 first isomer, BLi2 second isomer, B2Li2 first isomer, B2Li2 second isomer and BLi3 are the most stable among all 11 molecules of BxLiy (x = 1-3, y = 1-3). The stability of BxLiy (x = 1-3, y = 1-3) clusters depend on both the formation of geometrical structures on the number of Li atoms. As the number of Li atoms in the group increases, the stability of BxLiy clusters also increases. Within each group formation of geometrical structures, the stability of BxLiy clusters changes. It is observed that they may change the capability of chemical reactions in BxLiy clusters. © 2020 by the authors.