Rajan Kumar Singh; Neha Jain; Jai Singh; Ranveer Kumar
Abstract
This is the first time that a highly purified white organic electrolyte salts (OES), Methylammonium iodide, CH3NH3I (MAI) and Methylammonium chloride, CH3NH3Cl (MACl) have been successfully synthesized by a new technique, high vacuum oven evaporation method (HVOE), which is inexpensive and less time ...
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This is the first time that a highly purified white organic electrolyte salts (OES), Methylammonium iodide, CH3NH3I (MAI) and Methylammonium chloride, CH3NH3Cl (MACl) have been successfully synthesized by a new technique, high vacuum oven evaporation method (HVOE), which is inexpensive and less time consumable. Thermal stability of organic salt, pure and mixed perovskite light harvester materials (PLHM) are studied by STA (DTG/DTA). CH3NH3I and CH3NH3Cl undergo ~100% weight loss in one step, at temperature 310 o C and 350 o C, respectively. Additionally, CH3NH3PbI3 is more thermally stable than mixed halide perovskite CH3NH3PbI3-xCl. Stability behavior of organic salts and CH3NH3PbI3-xClx is analyzed by Raman study which indicates that organic salts are stable in ambient conditions and CH3NH3PbI3-xClx is not stable in ambient condition. Different stretching and banding modes of organic and inorganic materials are indentified by study of Raman spectra.
Partha P. Dey; Alika Khare
Abstract
In this letter, optical limiting property of the insufficiently oxidized silicon oxide (SiOx) thin films is reported. Films were deposited by Pulsed Laser Deposition technique using Q-switched Nd: YAG laser (532 nm) onto fused silica substrate at a substrate temperature of 400 °C by varying the O2 ...
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In this letter, optical limiting property of the insufficiently oxidized silicon oxide (SiOx) thin films is reported. Films were deposited by Pulsed Laser Deposition technique using Q-switched Nd: YAG laser (532 nm) onto fused silica substrate at a substrate temperature of 400 °C by varying the O2 pressure in the range of 5×10 -5 to 0.5 mbar. Energy Dispersive X-Ray spectra showed the increase in oxygen content with increasing O2 pressure. Raman spectra of SiOx films depicted the presence of micron sized clusters composed of nanocrystalline Silicon embedded in uniform matrix of oxidized amorphous Silicon. The open Z-scan of the thin films, under cw He-Ne laser irradiation, showed strong reverse saturation absorption (RSA) features and non linear absorption (NLA) coefficient, β, was found to be decreasing from 23.5 cm/W to 1.64 cm/W, with increase in O2 pressure from 5×10 -5 to 10 -1 mbar, respectively. Also, the SiOx films except that with maximum oxygen content showed optical limiting, where limiting threshold increases with increasing transparency controlled by oxygen content. The key feature of the present work is the tunability in linear absorption, nonlinear RSA and optical limiting in the SiOx films which can be used as novel material for optical switching application.
V. Saikiran; N. Manikanthababu; N. Srinivasa Rao; S. V. S. Nageswara Rao; A. P. Pathak
Abstract
Trilayered HfO2/Ge/HfO2 thin films were grown on Si substrate by RF magnetron sputtering with HfO2 and Ge targets. The subsequent rapid thermal annealing (RTA) of these films at 700 & 800°C results in formation of Ge nanocrystals (NCs) in HfO2 matrix. X-ray diffraction (XRD) and micro-Raman spectroscopy ...
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Trilayered HfO2/Ge/HfO2 thin films were grown on Si substrate by RF magnetron sputtering with HfO2 and Ge targets. The subsequent rapid thermal annealing (RTA) of these films at 700 & 800°C results in formation of Ge nanocrystals (NCs) in HfO2 matrix. X-ray diffraction (XRD) and micro-Raman spectroscopy measurements were performed to confirm the formation of Ge NCs in the annealed samples. XRD results indicate that the as-deposited samples show amorphous behaviour, whereas the annealed samples clearly confirm the crystallinity of the films. The average size of the Ge NCs was found to increase with an increase in annealing temperature. Raman scattering studies confirm that the annealed samples exhibit a shift in peak position corresponding to Ge-Ge optical phonon vibrations, which clearly indicates the formation of Ge NCs. Conversely, as-deposited samples were also irradiated with swift heavy ions of 150 MeV Au and 80 MeV Ni at a fluence of 3×10 13 ions/cm 2 to synthesize Ge NCs. The structural properties of pristine and irradiated samples have been studied by using X-ray diffraction, Raman spectroscopy to substantiate the growth of Ge NCs upon irradiation. The results obtained by RTA are compared with the irradiated ones.
Yasir Ali; A. S. Dhaliwal;R G Sonkawade; Vijay Kumar
Abstract
AnchorThe surface of polyaniline nanofibres is modified by silver nano particles using cyclic voltametry (CV). The surface modifications induced by silver particles are confirmed by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopic techniques. The SEM ...
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AnchorThe surface of polyaniline nanofibres is modified by silver nano particles using cyclic voltametry (CV). The surface modifications induced by silver particles are confirmed by scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and Raman spectroscopic techniques. The SEM micrographs show uniform distribution of silver particles on the surface of PANI nano fibers. Presence of silver particles was confirmed by EDX. Structural variations induced after reduction of Ag-metal particles and formation of polaron and bipolarons are studied by Raman spectroscopy.
Gagan Dixit; J.P. Singh; R.C. Srivastava; H.M. Agrawal; R.J. Chaudhary
Abstract
In the present work, structural, morphological, magnetic and optical properties of nickel ferrite thin films having different thickness are reported. All the films were deposited on Si (100) substrate by pulsed laser deposition technique. Thicknesses of the films determined by x-ray reflectivity vary ...
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In the present work, structural, morphological, magnetic and optical properties of nickel ferrite thin films having different thickness are reported. All the films were deposited on Si (100) substrate by pulsed laser deposition technique. Thicknesses of the films determined by x-ray reflectivity vary from 62 to 176nm as the deposition time varies from 16 min to 40 min. The films were characterised by x-ray diffractogram, Fourier transform infrared (FTIR) and Raman spectroscopy for structural and phase confirmation. FTIR and Raman spectra confirm mixed spinel nature of nickel ferrite. Surface morphology is studied by Atomic force microscopy. All the films have granular nature. Magnetic properties were studied by vibrating sample magnetometer and magnetic hysteresis curves were recorded for all the films at room temperature and at10K. At 10K, saturation magnetisation was found to increase while coercivity deceases with thickness. The results are explained on the basis of anisotropy induced by cation inversion and strain. Optical properties were studied by UV-vis reflectance spectra. The value of optical band gap (5.7eV) was found to be independent of thickness of the film.
