B. Valarmathi; R. Premanand; G. Vinitha; R. Mohan Kumar
Abstract
Organic materials have outstanding upturn striking high nonlinear optical properties. One such NLO material of good quality single crystal of protonated Piperazinium bis (Salicylate) (PSL) was synthesized by slow solvent evaporation solution growth technique. XRD studies analyzed that the PSL crystallize ...
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Organic materials have outstanding upturn striking high nonlinear optical properties. One such NLO material of good quality single crystal of protonated Piperazinium bis (Salicylate) (PSL) was synthesized by slow solvent evaporation solution growth technique. XRD studies analyzed that the PSL crystallize monoclinic system with space group P21/n. FTIR spectral analysis ascertained the frequencies of various functional groups present in PSL crystal. The optical transmittance and optical band gap were explored from the optical transmission phenomena of PSL crystal. PL studies revealed that prominent emission at 410 nm, when PSL was excited at 320 nm. The mechanically soft nature of the crystal was divulged by Vickers hardness measurement. The LDT value of PSL crystal was estimated as 2.65 GW/cm2. The third order NLO properties of PSL crystal was ascertained by Z-scan studies.
Mohammad Danish; Ashutosh Pandey
Abstract
Reactions of niobium (V) ethoxide (1) with 2,4-pentanedione derivatives [3-Chloro-2,4-pentanedione, 1,1,1-Trifluoro-2, 4 pentanedione, 3,3-Dimethyl-2,4-pentanedione,] afforded heteroleptic niobium alkoxide complexes [Nb(OEt)4 (CH3COCHClCOCH3)](2), [Nb(OEt)4(CF3COCH2COCH3)] (3) and [Nb(OEt)4(CH3COC(CH3)2COCH3)] ...
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Reactions of niobium (V) ethoxide (1) with 2,4-pentanedione derivatives [3-Chloro-2,4-pentanedione, 1,1,1-Trifluoro-2, 4 pentanedione, 3,3-Dimethyl-2,4-pentanedione,] afforded heteroleptic niobium alkoxide complexes [Nb(OEt)4 (CH3COCHClCOCH3)](2), [Nb(OEt)4(CF3COCH2COCH3)] (3) and [Nb(OEt)4(CH3COC(CH3)2COCH3)] (4). Two sets of Nb2O5 sculptured thin films (STFs) were deposited on ITO coated glass substrates by spin casting the gels obtained by sol gel processing of the synthesized complexes (2-4). One set of the films (Na, Nb and Nc) were calcined under ammonia gas flow and the other (a, b and c) under oxygen gas flow respectively at 500°C for 1h. A film (d) was also fabricated from niobium (V) ethoxide and calcined under oxygen gas flow at 500°C for 1h for comparisons with regard to structure, topography, optical and photocatalytic properties of Nb2O5. Crystal structure, topography, optical and photocatalytic properties of the films were determined by X-ray diffraction, atomic force microscopy, ellipsometry and UV-Vis spectroscopy. Significant band gap narrowing i.e. from 3.48 eV (d) to 2.73 eV (Nc) was observed for the films calcined under ammonia gas flux. Investigation of photodegradation of methylene blue (MB) by niobia films under UV irradiation demonstrated enhanced degradation efficiency of methylene blue dye. Copyright © 2018 VBRI Press.
Indu B. Vashistha; Mahesh C. Sharma; S.K. Sharma
Abstract
In this present study Cu2ZnSnS4 (CZTS) thin films were grown by Chemical Bath Deposition (CBD) method at optimized parameters. These as grown CZTS films were annealed at 3000C for different time 1 hr, 2 hr, 3 hr. These films were characterized by scanning electron microscope (SEM), UV-VIS Spectrophotometer, ...
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In this present study Cu2ZnSnS4 (CZTS) thin films were grown by Chemical Bath Deposition (CBD) method at optimized parameters. These as grown CZTS films were annealed at 3000C for different time 1 hr, 2 hr, 3 hr. These films were characterized by scanning electron microscope (SEM), UV-VIS Spectrophotometer, I-V measurement for study of surface morphology, optical and electrical properties respectively. The SEM analysis revealed that surface modification takes place as the annealing time increases. The optical study shows high absorption in visible region and as annealing time increase red shift in energy band gap occurred. The current-voltage characteristics of the specimen indicated that conductivity of film increases with increased annealing time. Thus, annealing time has prominent impact on surface modification which changes optoelectronic properties of CZTS thin film and results shows that film annealed at 3000C for 3 hr gives high absorption and better conductivity for CZTS thin films. Copyright © 2018 VBRI Press.
M.K. Debanath; R.K. Saha; S.M. Borah; E. Saikia; K.K. Saikia
Abstract
In our present investigation, we have synthesized starch-capped Cu doped ZnO (ZnO:Cu) nanoparticles (NPs) by simple wet chemical method and studied their structural, optical and antibacterial effects on/against Gram-positive and Gram-negative bacteria. Chemically synthesized nanoparticle have been characterized ...
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In our present investigation, we have synthesized starch-capped Cu doped ZnO (ZnO:Cu) nanoparticles (NPs) by simple wet chemical method and studied their structural, optical and antibacterial effects on/against Gram-positive and Gram-negative bacteria. Chemically synthesized nanoparticle have been characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive analysis of X-rays (EDAX), high resolution transmission electron microscopy (HRTEM), UV-vis absorption spectroscopy and photoluminescence (PL) spectroscopy for their structural and optical properties. Antibacterial properties have been studied by Staphylococcus aureus (S. aureus, Gram-positive) and Escherichia coli (E. coli, Gram-negative) bacteria. XRD study showed hexagonal wurtzite crystal structure of the prepared ZnO:Cu and nanoformation of the as-synthesized NPs. Nanoparticle formation have been finally confirmed by HRTEM analysis. Antibacterial studies showed excellent resistance of ZnO:Cu to S. aureus and E. coli respectively. Copyright © 2018 VBRI Press.
Bhawana Joshi; Santanu Ghosh; Pankaj Srivastava
Abstract
In the present work, ZnO thin films deposited by pulsed laser deposition (PLD) technique have been characterized structurally and optically after post-deposition annealing. As-deposited thin films were annealed in the ambient atmosphere for different annealing temperatures of 2000C, 4000C, 6000C and ...
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In the present work, ZnO thin films deposited by pulsed laser deposition (PLD) technique have been characterized structurally and optically after post-deposition annealing. As-deposited thin films were annealed in the ambient atmosphere for different annealing temperatures of 2000C, 4000C, 6000C and 8000C. X-ray diffraction (XRD) technique was used for structure analysis and elucidated that both as-deposited and annealed films were of good structural quality and highly oriented towards c-axis. UV-Vis spectrophotometer was used to study the transmittance and optical band gap of as-deposited and annealed films. Photoluminescence (PL) technique was used to investigate the photoluminescent properties of all the films. It was found that ZnO thin films were highly transparent in nature and showed two emissions in PL spectra. One was attributed to near band edge (NBE) emission and the other was the broad deep-level (DL) emission. There was a significant change in the photoluminescent properties of the films and it was observed that the intensity of the DL emission increased significantly with the increase in the annealing temperature. The change in DL emission is attributed to the change in defect states inside the band gap of the annealed films. From the present work, it is inferred that the properties of the ZnO films can be tuned by post-deposition annealing for various applications such as optical and optoelectronic devices. Copyright © 2017 VBRI Press.
P. Prabukanthan; R. Lakshmi; T. Rajesh Kumar; S. Thamaraiselvi; G. Harichandran
Abstract
Electrochemical deposition (ECD) of FeS2 thin films from aqueous solution contains FeSO4, Na2S2O3.5H2O and H2SO4. ECDs were performed at different bath temperatures (30, 40, 50, 60 and 70°C) with constant pH (~2). FESEM images shows that the grains are as deposited films with stoichiometric ...
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Electrochemical deposition (ECD) of FeS2 thin films from aqueous solution contains FeSO4, Na2S2O3.5H2O and H2SO4. ECDs were performed at different bath temperatures (30, 40, 50, 60 and 70°C) with constant pH (~2). FESEM images shows that the grains are as deposited films with stoichiometric iron pyrite thin films were successfully formed at 50, 60 and 70°C and S/Fe ratio in as-deposited films were ~2. GAXRD studies of as-deposited at 30 and 40°C FeS2 thin films shows a minor phase of orthorhombic marcasite and major cubic pyrite phase observed. As-deposited thin films at 50, 60 and 70°C brings about the formation of FeS2 with single crystalline cubic phases with a strong (111) preferred orientation and without any contribution of marcasite phase. When the bath temperature was increased, as-deposited thin films of crystalline size, thickness and roughness value increased due to rate of formation FeS2 increased. Raman spectra of the FeS2 thin films presented characteristic peaks of S-S active mode at 377 cm-1. The optical spectra of the as-deposited FeS2 thin films with different bath temperatures showed a clear absorption edge band gap of these films from 0.86 to 0.96 eV. As-deposited FeS2 thin films at different bath temperatures show p-type conductivity. Copyright © 2017 VBRI Press.
Vinod Karar; Amit L Sharma
Abstract
Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being ...
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Beam splitters are primarily used for applications like avionic displays, optical storage, fluorescence applications, optical interferometry, semiconductor instrumentation where some of the information needs to be reflected as well as transmitted. They operate on the principle of light being reflected and transmitted by various interfaces where it is split by percentage of overall intensity or wavelength. In this study, design and fabrication of a dichroic optical beam splitter for filtering of red and green light from a white light source has been presented. Here, a symmetric dielectric multilayer stack with 15 alternating layers of alumina and silica are deposited on BK-7 glass using e-beam evaporation technique. High and low refractive indices of 1.63 and 1.46 respectively are used with quarter-wave optical thicknesses of layers. The beam splitter is designed for 45 ̊ angle of incidence using FilmstarTM design software. Transmission spectrum obtained from UV-Vis-NIR double beam spectrophotometer shows reflectance of ~54% at 660 nm (red wavelength region) and transmittance of ~88% at 550 nm (green wavelength region). The coated sample is further subjected to adhesion and hardness test according to MIL standard and no peel off or scratch is observed indicating excellent durability of the coating. The modelled and measured results closely agree with one another over visible spectral regions. Copyright © 2017 VBRI Press.
P. Rosaiah; G. Lakshmi Sandhya; S. Suresh; Jinghui Zhu; Yejun Qiu; O. M. Hussain
Abstract
Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the ...
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Vanadium pentoxide (V2O5) thin films have been prepared onto ITO coated flexible Kapton substrates by electron beam evaporation technique. The influence of substrate temperature on the structural, morphological, optical and electrical properties has been investigated. The XRD results reveals that the films prepared at lower temperatures are amorphous in nature and the films prepared at 300 oC is exhibited predominant (001) orientation with an orthorhombic crystal structure. AFM study showed that the grain size varies from 80 nm to 150 nm. The optical studies revealed that the transmittance decreased with increasing substrate temperature. The optical absorption coefficient ‘a’ determined from the experimentally measured transmittance and reflectance data for V2O5 films was found to give a better fit for the exponent n = 3/2 suggesting the direct forbidden transitions with an estimated optical band gap of 2.31 eV for the films prepared at 300 oC. The electrical conductivity has been observed to be increased from 2 x 10-6 S/cm to 3 x 10-2 S/cm by varying temperature from 30 oC to 300 oC. The electrochemical experiments exhibited the discharge capacity of about 60 μAh/(cm2-μm) for the films deposited at 300 oC.
