Department Of Physics
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Item Promising field electron emission performance of vertically aligned one dimensional (1D) brookite (?) TiO2 nanorods(Royal Society of Chemistry, 2016) Devan, R.S.; Ma, Y.-R.; More, M.A.; Khare, R.T.; Antad, V.V.; Patil, R.A.; Thakare, V.P.; Dhayal, R.S.; Schmidt-Mende, L.We evidence field-electron emission (FE) studies on the large-area array of one-dimensional (1D) brookite (?) TiO2 nanorods. The pure 1D ?-TiO2 nanorods of 10 nm width and 760 nm long were synthesized on Si substrate utilizing hot-filament metal vapor deposition technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis evidenced the ?-TiO2 nanorods to be composed of orthorhombic crystals in brookite (?) phase. X-ray photoemission spectroscopy (XPS) revealed the formation of pure stoichiometric (i.e. 1 : 1.98) 1D TiO2 nanorods. The values of turn-on field, required to draw current density of 10 ?A cm-2, was observed 3.9 V ?m-1 for pristine 1D ?-TiO2 nanorods emitters, which were found significantly lower than doped/undoped 1D TiO2 nanostructures (i.e. nanotubes, nanowires, nanorods) based field emitters. The enhanced FE behavior of the TiO2/Si emitter can be attributed to modulation of electronic properties due to the high aspect ratio of vertically aligned TiO2 nanorods. Furthermore, the orthodox emission situation of pristine TiO2/Si emitters exhibit good emission stability and reveal their potentials as promising FE material. ? 2016 The Royal Society of Chemistry.Item Highly stable supercapacitive performance of one-dimensional (1D) brookite TiO2 nanoneedles(Royal Society of Chemistry, 2016) Devan, R.S.; Ma, Y.-R.; Patil, R.A.; Lukas, S.-M.We report the highly stable supercapacitive performance of one-dimensional (1D) nanoneedles of brookite (?) TiO2 synthesized on a conducting glass substrate. The 1D ?-TiO2 nanoneedles synthesized over a large area array utilizing hot-filament metal vapor deposition (HFMVD) were ?24-26 nm wide, ?650 nm long and tapered in a downward direction. X-ray photoemission spectroscopy (XPS) revealed their chemical properties and stoichiometric Ti and O composition. The 1D ?-TiO2 nanoneedles execute as parallel units for charge storage, yielding a specific capacitance of 34.1 mF g-1. Electrochemical impedance spectroscopy revealed that the large surface area and brookite crystalline nature of the 1D nanoneedles provided easy access to Na+ ions, and resulted in low diffusion resistance, playing a key role in their stable charging-discharging electrochemical mechanism. Moreover, the non-faradic mechanism of these nanoneedles delivered better durability and high stability up to 10000 cycles, and a columbic efficiency of 98%. Therefore, 1D ?-TiO2 nanoneedles hold potential as an electrode material for highly stable supercapacitive performance with long cycle lifetime. ? 2016 The Royal Society of Chemistry.Item Electron transport behavior and charge ordering phenomena in La0.5Ca0.5MnO3(Elsevier Ltd, 2016) Kekade, S.S.; Devan, R.S.; Deshmukh, A.V.; Phase, D.M.; Choudhary, R.J.; Patil, S.I.In this study, the polycrystalline sample of La0.5Ca0.5MnO3 (LCMO) with perovskite (Orthorhombic) crystalline structure was synthesized by citrate gel method. The temperature dependent magnetization studies exhibit both paramagnetic to ferromagnetic and ferromagnetic to antiferromagnetic transition of LCMO at ?230 K and ?150 K, respectively. The X-ray photoemission spectroscopy data revealed electronic structures, chemical properties, while the valence band photoemission spectra for LCMO measured at various photon energies ranging from 40 eV to 60 eV, showed Fano curve like resonance behavior for Mn 3p to 3d transition and also confirmed the change of DOS near Fermi level. ? 2016 Elsevier B.V.