Department Of Physics
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Item Titania sensitized with SPADNS dye for dye sensitized solar cell(Springer New York LLC, 2016) Didwal, P.N.; Pawar, K.S.; Chikate, P.R.; Abhyankar, A.C.; Pathan, H.M.; Devan, R.S.Synthesis of anatase TiO2 nanoparticle with diameter about 25?nm is carried out by using chemical method and powder of TiO2 nanoparticle is pasted on fluorine doped tin oxide (FTO) coated glass by doctor blade. New organic SPADNS dye (C16H9N2Na3O11S3) is used first time to make the dye-sensitized solar cells (DSSC). Cell were constructed by using SPADNS dye loaded wide band gap anatase TiO2 nanoparticle on FTO coated glass as photo-anode, polyiodide as electrolyte, and platinum coated FTO as counter electrode. SPADNS dye was made from organic reagent which is low cost and easy available in market. Better adsorption of SPADNS dye on anatase TiO2 film is due to porous nature of TiO2. This better adsorption gives more transportation of electron from dye to TiO2 which increase the efficiency of solar cell. Although SPADNS dye is the first experiment with TiO2 nanoparticle for DSSC, it gives photocurrent (short-circuit current density) 1.04?mA/cm2, open-circuit voltage 0.59?V, with 0.9?% efficiency under 10?mW/m2 LED. ? 2016, Springer Science+Business Media New York.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 Facile chemical bath deposition method for interconnected nanofibrous polythiophene thin films and their use for highly efficient room temperature NO2 sensor application(Elsevier B.V., 2017) Kamble, D.B.; Sharma, A.K.; Yadav, J.B.; Patil, V.B.; Devan, R.S.; Jatratkar, A.A.; Yewale, M.A.; Ganbavle, V.V.; Pawar, S.D.Interconnected nanofibrous polythiophene (INPTh) film was deposited on the glass substrate through a simple chemical bath deposition method. The influence of monomer concentration on INPTh film properties as well as on NO2sensing properties of the film was studied. The morphological and structural studies were carried out using FTIR spectroscopy, FE-SEM microscope, and AFM analysis. The FTIR spectra confirmed the formation of PTH structure. The interconnected nanofibrous surface morphology was observed in FE-SEM images. The roughness of the film and thickness (225?nm?442?nm) was found to increase with monomer concentration up to 0.5?M, after that, both decreased at 0.6?M monomer concentration. The highest selectivity of PTh thin film towards NO2was observed than the other gases like H2S, SO2, NH3, CO and LPG. The influence of film morphology and thickness on gas sensing properties was observed, which was varied with monomer concentration. The film deposited at 0.5?M monomer concentration showed the highest NO2gas response of 47.58% at room temperature. Present results revealed that monomer concentration was also one of the deposition parameters for tuning the morphological as well as gas sensing properties of the chemical bath deposited PTh film. ? 2017 Elsevier B.V.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.Item Correlation between structural, magnetic and ferroelectric properties of Fe-doped (Ba-Ca)TiO3 lead-free piezoelectric(Elsevier Ltd, 2017) Keswani, B.C.; Devan, R.S.; Kambale, R.C.; James, A.R.; Manandhar, S.; Kolekar, Y.D.; Ramana, C.V.The effect of iron (Fe) doping modification on the structure and properties of Ba0.92Ca0.08TiO3 (BCT8) lead-free ferroelectrics is investigated in detail. Intrinsic BaTiO3 (BT) and Ba0.92Ca0.08TiO3 (BCT8) lead-free polycrystalline ceramics were synthesized by conventional solid-state chemical reaction method. The crystal structure, morphology, chemical composition and valence state, magnetic and ferroelectric properties of BCT8 ceramics were evaluated as a function of variable Fe-content (0–5 wt%). X-ray diffraction measurements coupled with Rietveld refinement analyses indicate that the BT, BCT8, and Fe-BCT8 ceramics crystallize in single phase tetragonal structure. Phase transformation occurs with higher Fe doping; Fe-BCT8 ceramics with 5 wt% Fe exhibits fully transformed orthorhombic structure. The crystal structure and phase formation of these ceramics was further confirmed by the Raman spectroscopic (RS) measurements. The RS data coupled with high-resolution X-ray photoelectron spectroscopic (XPS) analyses also confirm the formation of single phase materials without any presence of secondary or impurity phases. Microstructure imaging analyses indicate that the grain size was ∼1 μm, while agglomeration and inhomogeneous distribution were observed with Fe doping. Polarization-electric field (P-E) hysteresis and strain-electric field (S-E) hysteresis measurements revealed the ferroelectric and piezoelectric nature of the ceramics. Ferroelectric and piezoelectric properties were observed to be suppressed for Fe doped BCT8 ceramics due to the partial replacement of Ti4+ by Fe3+ as confirmed by the chemical analyses made using XPS. Temperature dependent dielectric measurements for Fe doped BCT8 show a drastic decrease in ferroelectric Curie temperature (Tc), along with a decrease in dielectric constant compared to that of undoped BCT8. Magnetization (M-H) measurements confirm the presence of long-range magnetic ordering for 5% Fe-doped BCT8 sample. The results demonstrate that addition of 5% Fe in lead-free BCT8 perovskite induces the magnetic ordering and a switchable ferroelectric state, which evidences the presence of multiferroic nature that can be used for four-bit memory and switching applications.