Ravi Jon; Vipul Singh; D.P Jayapandian
Abstract
The main aim of this research is to propose the various green reducing agents for extract the green gold nanoparticles from Gold Chloride (HAucl4) solution. Green reducing agents are safe and eco-friendly for the extraction of the gold nanoparticles. The green gold nanoparticles were synthesized using ...
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The main aim of this research is to propose the various green reducing agents for extract the green gold nanoparticles from Gold Chloride (HAucl4) solution. Green reducing agents are safe and eco-friendly for the extraction of the gold nanoparticles. The green gold nanoparticles were synthesized using plant and fruit extract, and green Gold nanoparticles were characterized using SEM, TEM, and UV-Vis. Spectroscopy. The absorption peak was observed at 530-540 nm, which proved the green gold nanoparticles. Green Gold nanoparticles in the size of 30 nm in the spherical shape were confirmed by transmission electron microscopy. The toxicity of green gold nanoparticles is less than gold nanoparticles. These green gold nanoparticles can be used in various biomedical applications. Green reducing agents are the best alternative for the synthesis of the gold nanoparticles. Copyright © 2017 VBRI Press.
Arti I. Nandapure; Subhash B. Kondawar; Bharti I. Nandapure; Manish M. Choudhari
Abstract
Polyaniline/ferrite nanocomposites have attracted increasing attention because they offer the possibility of a new generation of nanostructure materials with advanced applications like electromagnetic interference shielding, rechargeable batteries, corrosion devices due to their flexibility, inexpensive ...
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Polyaniline/ferrite nanocomposites have attracted increasing attention because they offer the possibility of a new generation of nanostructure materials with advanced applications like electromagnetic interference shielding, rechargeable batteries, corrosion devices due to their flexibility, inexpensive and easy of synthesis. Polyaniline (PANI) containing MFe2O4 were prepared by in-situ polymerization of aniline in aqueous solution (Where M-represent divalent metal cation, M2+ = Ni2+). PANI reduces the agglomeration of nanosized nickel ferrite (NiFe2O4) particles which is good for the stabilization of nanoparticles. The investigation of structural, morphological and optical properties was carried out for the synthesized PANI/NiFe2O4 nanocomposites using X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Ultraviolet visible spectrophotometer (UV-Vis). XRD revealed that the structure of NiFe2O4 nanoparticles is spinel with space group Fd3m and crystallite size 14 nm. Lattice parameter was found to increases with NiFe2O4 concentration in PANI and this may be due to the larger ionic radius of the Ni2+ ion. XRD pattern of PANI/NiFe2O4 nanocomposites at different ferrite molar percent are just the superposition of those of polyaniline and ferrite nanoparticles. Transmission electron microscopy of PANI/NiFe2O4 nanocomposites show increase in particle size over pure a NiFe2O4 nanoparticles which is relevant with XRD results. UV-Visible absorption spectroscopy of PANI/NiFe2O4 nanocomposites shows two absorption bands in range of 300-350 nm and 600-650 nm which reflects interaction of ferrite nanoparticles with PANI. Copyright © 2017 VBRI Press.
Harishchandra Singh; Ashok K. Yadav; Manavendra N. Singh; Anil K. Sinha
Abstract
Fe2TeO6 (FTO), an antiferromagnetic magnetoelectric material which crystallizes in tetragonal (P42/mnm, 136) crystal structure, shows close to room temperature interesting magnetic interactions. To understand the complexity in its magnetism, a huge variation in its magnetic properties has been reported ...
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Fe2TeO6 (FTO), an antiferromagnetic magnetoelectric material which crystallizes in tetragonal (P42/mnm, 136) crystal structure, shows close to room temperature interesting magnetic interactions. To understand the complexity in its magnetism, a huge variation in its magnetic properties has been reported by various groups, which have been attributed to the presence of Fe2O3 (an impure phase) in the final FTO compound. Herein, synthesis using alternate ingredients and Synchrotron structural investigation of single phasic FTO are presented. Out of the several initial ingredients (Fe2O3, Fe3O4 with TeO2, Te(OH)6) in solid state reaction route, only the reaction between Fe3O4 and TeO2 results in the single phasic FTO (not reported so far), while the others (Fe2O3 with TeO2 or Te(OH)6) result in certain amount of Fe2O3 impurity. Rietveld refinement on Synchrotron X-ray Diffraction data and Fe K edge Extended X-ray Absorption Fine Structure data provide the overall similarity between the average crystalline structure and local structure of FTO, indicating the intrinsic nature of it’s complex magnetic behavior. Copyright © 2017 VBRI Press.
Uma Narang; Kumar K. Yadav; Soumee Bhattacharya; S.M.S. Chauhan
Abstract
The selected porphyrin acids such as 5-(4'-carboxyphenyl)-10,15,20-triphenylporphyrin, 5-(4'-carboxyphenyl)-10,15,20-tris-(4''-chlorophenyl)porphyrin, 5-(4'-carboxyphenyl)-10,15,20-tris-(4''-tertbutylphenyl)porphyrin and 5-(4'-carboxyphenyl)-10,15,20-(4''-pyridyl)porphyrin have been synthesised by reaction ...
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The selected porphyrin acids such as 5-(4'-carboxyphenyl)-10,15,20-triphenylporphyrin, 5-(4'-carboxyphenyl)-10,15,20-tris-(4''-chlorophenyl)porphyrin, 5-(4'-carboxyphenyl)-10,15,20-tris-(4''-tertbutylphenyl)porphyrin and 5-(4'-carboxyphenyl)-10,15,20-(4''-pyridyl)porphyrin have been synthesised by reaction of two aldehydes with pyrrole in propionic acid.The coupling of 5-(4'-carboxyphenyl)-10,15,20-triarylporphyrins with pentan-1,5-diol in presence of EDC and DMAP give unsymmetrical bisporphyrins, which were metallated with zinc acetate to give different porphyrin tweezers. The singlet oxygen efficiency of porphyrin tweezers as photosensitizers have been quantified by monitoring the transformation of1,3-diphenylisobenzofuran (DPBF) to 1,2-dibenzoylbenzene by UV-visible spectroscopy. The quantum yield of formation of singlet oxygen for different porphyrin tweezers have been examined. The electron withdrawing group containing porphyrin tweezer is a better photosensitizer than electron donating group in generation of singlet oxygen. Copyright © 2017 VBRI Press.
Sourabh Biswas; Sam Allison; S. Habib Alavi; Sandip P. Harimkar
Abstract
In the present investigation, effect of laser melting with and without simultaneous application of ultrasonic vibrations on electrochemical properties of 2024 aluminum alloy is investigated. The electrochemical behavior of the laser melted specimens was studied using open-circuit and potentiodynamic ...
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In the present investigation, effect of laser melting with and without simultaneous application of ultrasonic vibrations on electrochemical properties of 2024 aluminum alloy is investigated. The electrochemical behavior of the laser melted specimens was studied using open-circuit and potentiodynamic polarization measurements. Subsequently, investigation of the corrosion films was performed using scanning electron microscopy. It was observed that the laser melted specimens exhibited significant improvement in open circuit potential (both with and without simultaneous ultrasonic vibration application). The open circuit potential of the laser melted specimen without ultrasonic vibrations was observed to be more stable compared to the laser melted specimen with ultrasonic vibrations. It was observed that the corrosion mechanism undergoes a transition from pitting to uniform corrosion in the laser treated specimen, particularly in the laser melted specimen without ultrasonic vibrations. However, the extensive agitations due to ultrasonic vibrations in the melt pool appear to restrict Cu migration to grain boundaries that result in porous and relatively inefficient passive layer formation in laser processed samples with application of ultrasonic vibrations. This behavior was also observed in the potentiodynamic polarization studies that showed that the laser melted specimen without ultrasonic vibrations exhibited lower corrosion current and corrosion rate compared to the laser melted specimen with ultrasonic vibrations as well as the as received substrate. Copyright © 2017 VBRI Press.
Rajnish Kumar; S. A. R. Hashmi; Subhash Nimanpure; Ajay Naik
Abstract
Randomly distributed kenaf fibre with varying length (5-50mm) and weight fractions (25-40%) were used to reinforce epoxy resin to prepare environment friendly composites. Effect of fibre length with constant fibre loading on dynamic mechanical properties was studied and its effect on storage modulus, ...
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Randomly distributed kenaf fibre with varying length (5-50mm) and weight fractions (25-40%) were used to reinforce epoxy resin to prepare environment friendly composites. Effect of fibre length with constant fibre loading on dynamic mechanical properties was studied and its effect on storage modulus, loss modulus and damping factor were investigated. Kenaf fibres were also subjected to alkali treatment to improve interaction with the epoxy resin. The mechanical properties of composites improved with the length and loading of fibres. Tensile strength, flexural strength and impact strength of composites at 40 wt% of fibre reinforcement improved by 46, 51 and 97% as compared to the composites containing 25 wt% of kenaf fibre. It was also observed that fibre folds developed during mixing became significant factor which limited the improvement in mechanical strength of kenaf epoxy composites. A few important predictive models namely rule of mixture, Haplin-Tsai, Nielson Chen and Manera models were compared with the experimental values obtained in this present study. Manera model predicted the experimental data most accurately. Alkali treatment improved the interface and its outcome reflected in the improved modulus that increased 21.76% in samples having 10mm length of kenaf fibre. Copyright © 2017 VBRI Press.
Sunita Barot; Neelkumar Gadhiya; Maaz Nawab; Rajib. Bandyopadhyay
Abstract
Sulphated zirconia, one of the most efficient solid acid catalysts, has been explored in present studies for transesterification reaction. The catalyst was synthesized by conventional precipitation method and characterized by XRD, TGA, FTIR and total acidity. The catalyst exhibits excellent activity ...
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Sulphated zirconia, one of the most efficient solid acid catalysts, has been explored in present studies for transesterification reaction. The catalyst was synthesized by conventional precipitation method and characterized by XRD, TGA, FTIR and total acidity. The catalyst exhibits excellent activity for transesterification of model triglyceride triacetin as well as Jatropha oil with high selectivity towards the formation of monoalkyl esters. Influence of various reaction parameters such as triglyceride/alcohol molar ratio, catalyst amount, reaction temperature and reaction time on catalytic performance were studied over model triglyceride. The maximum 96 % yield of methyl acetate was achieved in 3 hours at 10 wt% catalyst loading with triglyceride to methanol ratio 1:15 and 70o C reaction temperature. The kinetic studies were also done and found that reaction follows first order kinetics and reaction rates are not mass transfer limited. The optimized reaction parameters were extended for biodiesel synthesis from Jatropha oil and FAME yield of 82 % could be successfully achieved. Hence, Sulphated zirconia is a promising catalyst for heterogeneous transesterification of triglycerides, which is more productive and environment-friendly as compared to conventional homogeneous transesterification. Copyright © 2017 VBRI Press.
Hemlata J. Sharma; Megha A. Salorkar; Subhash B. Kondawar
Abstract
Electrospun nanofibers of Polyaniline (PANI)/SnO2 composite based gas sensor for hydrogen (H2) and carbon monoxide (CO) gas were prepared by electrospinning technique. The synthesized material was characterized using UV-Visible, XRD and SEM-EDX analyses. The average diameter of PANI/SnO2 composite was ...
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Electrospun nanofibers of Polyaniline (PANI)/SnO2 composite based gas sensor for hydrogen (H2) and carbon monoxide (CO) gas were prepared by electrospinning technique. The synthesized material was characterized using UV-Visible, XRD and SEM-EDX analyses. The average diameter of PANI/SnO2 composite was found to be high as compared to that of pristine SnO2 nanofibers having 200 nm diameter may be due to micelle formation of PANI on the surface of SnO2 nanofibers.The enhanced sensing properties in the form of sensitivity factor, time taken to response and recovery during exposure and de-exposure of Gas and repeatability were studied. The SnO2/PANI composite nanofibers showed high sensitivity and response to H2 gas compared to CO gas to 0.1% and maximum sensitivity was observed at 35˚C for H2 gas. Fast Response-Recovery Time for 1000-5000 ppm of H2 i.e. less than 30 secs were observed. Due to room temperature operation of the sensor, it is promising for environmental applications. The results indicate that aligned SnO2/PANI composite fibers are promising candidate for fast detection of H2 gas. Copyright © 2017 VBRI Press.
Vinay Sharma; Priyanka Rani; Bijoy K. Kunar
Abstract
Recently, there has been significant interest on the fundamental science and technological applications of complex oxides and multiferroics. Low-power multiferroic have potential to fabricate and characterize frequency tunable, compatible with MMIC Technology, small light-weight for hand-held operation, ...
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Recently, there has been significant interest on the fundamental science and technological applications of complex oxides and multiferroics. Low-power multiferroic have potential to fabricate and characterize frequency tunable, compatible with MMIC Technology, small light-weight for hand-held operation, cost-effective, high-frequency (>10GHz), devices for next generation communication devices and military applications. Multiferroic materials consists of both magnetic and ferroelectric phase and they offer the possibility of magneto-electric (ME) coupling. The purpose of this research is to show strong magnetic field dependent frequency tuning of multiferroics (Nickel doped BFO – BiFe1-xNixO3) based devices over a broad frequency band. We have shown here the magnetic field control of ferromagnetic resonance (FMR) field/frequency from C to Ku band frequencies. Nanoparticles of BiFe1-xNixO3 (x=0.025 & 0.05) were prepared by auto combustion method. The XRD study confirms the formation of pure phase Bismuth Ferrite Nanoparticles. Ferromagnetism of un-doped BFO was enhanced by Ni substitution. Microwave characterization was done in co-planar waveguide (CPW) geometry both in field sweep and frequency sweep mode. BiFe1-xNixO3 nanoparticles were deposited using electrophoretic deposition method (EPD) on top of CPW to do the FMR experiments. The operating frequency of the device was tuned by application of magnetic field (H) over a wide range (5 to 20 GHz) with a field up to 8 kOe.
Paviter Singh; Manpreet Kaur; Gurpreet Kaur; Bikramjeet Singh; Kulwinder Singh; Harpreet Kaur; Mandeep Singh; Manjeet Kumar; Rajni Bala; Ramovatar Meena; Akshay Kumar
Abstract
Boron carbide is well known metallurgical product used in cutting/coating tool industry. Nanostructured boron carbide finds its application in medical, optical and defence industry due to its structural, mechanical and optical properties. In present paper, we report the effect of processing parameters ...
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Boron carbide is well known metallurgical product used in cutting/coating tool industry. Nanostructured boron carbide finds its application in medical, optical and defence industry due to its structural, mechanical and optical properties. In present paper, we report the effect of processing parameters (reaction time and temperature/pressure) on the synthesis of nanostructured boron carbide. Detailed X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) analysis was done along with theoretical studies of pressure. Results show that the best temperature for synthesis of nanoscale boron carbide is 800 °C. Copyright © 2017 VBRI Press.
Mukta Behera; Rozalin Panda; Naresh C. Mishra; Ramakanta Naik
Abstract
In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 ...
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In the present work, structural, microstructural, compositional and electronic band gap properties of As40Se60 and As40Bi15Se45 bulk and thin films are reported. The films were prepared by thermal evaporation technique under high vacuum. X-ray diffraction (XRD) study indicated amorphous nature of As40Se60 in bulk prepared by melt quenching technique. Bi incorporation in As40Se60 with composition Bi15As40Se45 however led to nucleation of Bi2Se3 nanocrystallites in the amorphous matrix of As40Se60. The films made out of the two targets of composition As40Se60 and As40Bi15Se45 did not show any XRD peak, indicating their amorphous nature. UV-Visible-NIR spectroscopic study indicated a large decrease in the electronic band gap from 1.74 eV in films of composition As40Se60 to 1.28 eV for compositon Bi15As40Se45. This decrease is explained on the basis of a high concentration of defect states leading to the presence of localized states in the band gap due to Bi incorporation. Field emission scanning electron microscopy (FESEM) images show smooth and homogeneous surface for the As40Se60 films, while Bi incorporation led to increases of the surface roughness in the Bi15As40Se45 films. The decreased band gap and increased surface roughness on Bi incorporation in As40Se60 films indicate the suitability of these films for solar cell applications.
Biju Thangjam; Ibetombi Soibam
Abstract
Ni-Cu-Zn ferrites with compositional formula Ni0.8-xCuxZn0.2Fe2O4, where 0.0≤x≤0.5 in steps of 0.1 were synthesized by the citrate precursor method. The samples were subjected to final sintering at 900ᵒC for 2h after a pre-sintering at 600ᵒC for 4h. X-ray diffraction patterns confirmed the ...
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Ni-Cu-Zn ferrites with compositional formula Ni0.8-xCuxZn0.2Fe2O4, where 0.0≤x≤0.5 in steps of 0.1 were synthesized by the citrate precursor method. The samples were subjected to final sintering at 900ᵒC for 2h after a pre-sintering at 600ᵒC for 4h. X-ray diffraction patterns confirmed the formation of single phase spinel structure. The average crystallite size was calculated using Scherrer’s formula and was found to vary from 33nm to 39nm, clearly indicating the formation of nanoparticles. The infrared spectra were recorded at room temperature for all the samples in the range of 450 cm‾1 to 4000 cm‾1 using Perkin Elmer FT-IR Spectrometer. Jahn-Teller effect emerges which can be identified through the FT-IR Spectroscopy of the samples. This phenomenon may result in useful electro and magneto- optical applications. Possible mechanism is being discussed. Copyright © 2017 VBRI Press.
Sayantan Pathak; Niladri Biswas; Barun Jana; Tanmay K Ghorai
Abstract
The synthesis and crystal structure of Cu2(C6H5COO)4(C6H5COOH)2 (1) is herein reported. However, our intention was to incorporate Pb into the present system and make a new high nuclearity heteronuclear Cu-Pb cluster with magnetic or antibacterial properties. For its synthesis, first Cu (NO3)2.3H2O (2mmol) ...
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The synthesis and crystal structure of Cu2(C6H5COO)4(C6H5COOH)2 (1) is herein reported. However, our intention was to incorporate Pb into the present system and make a new high nuclearity heteronuclear Cu-Pb cluster with magnetic or antibacterial properties. For its synthesis, first Cu (NO3)2.3H2O (2mmol) and PhCOOH (10mmol) was dissolved in a mixed solvent MeCN/EtOH (10/10, v/v); separately Pb(NO3)2 (1mmol) was dissolved in EtOH/H2O (20/5, v/v) and added drop-wise to the previous mixture. The mixture was stirred vigorously for half an hour with step-wise addition of NaN3 (2mmol). The heterogenous reaction mixture was filtered and the deep greenish filtrate was stored at ambient condition. In four weeks, green single crystals were generated at the bottom of the flask. Single crystal X-ray measurement shows the formation of the title compound, where Cu atoms are in +2 oxidation state that is further confirmed by BVS calculation. The Cu-Cu distance in the molecular structure is found to be 2.608 (2) Å, which indicates a Cu-Cu bond in the molecule. Each Cu atom is bonded to four oxygen atoms of two benzoate ligands and one oxygen atom of a benzoic acid molecule. The octahedral geometry of the copper(II) atoms are fulfilled by an additional copper-copper bond. The most interesting in complex 1 is both intra and intermolecular hydrogen and C-H-C bonding present in the system. The length of nano molecular size of the Cu2 cluster is found to be 1.55nm. The antibacterial study of complex 1 has been checked and it has no such high antibacterial activity. Copyright © 2017 VBRI Press.
Sanatombi Sorokhaibam; Ibetombi Soibam; Sumitra Phanjoubam
Abstract
Substituted lithium ferrite having the chemical formula Li0.35 Ni0.1 Mn0.1 Zn0.2 Fe2.35 O4 have been synthesized by the citrate precursor method. The sample was given pre-sintering at 650oC in a conventional furnace. Final sintering was carried out at 900oC in a conventional surface and another ...
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Substituted lithium ferrite having the chemical formula Li0.35 Ni0.1 Mn0.1 Zn0.2 Fe2.35 O4 have been synthesized by the citrate precursor method. The sample was given pre-sintering at 650oC in a conventional furnace. Final sintering was carried out at 900oC in a conventional surface and another in a microwave furnace. The spinel phase structure of the conventional (CS) and microwave sintered (MS) samples was confirmed by the XRD patterns. From the analysis of XRD data, the crystallite size of the samples was estimated and smaller crystallite size was observed in the microwave sintered sample. Scanning Electron Microscopy (SEM) was also carried out. The dielectric studies were investigated. Room temperature dielectric constant ( ) and dielectric loss (tan d) were studied as a function of frequency. Experimental results show dispersion for variation of dielectric constant and dielectric loss tangent with frequency for both CS and MS sample. However, microwave sintered sample show lower dielectric constant and losses. Possible mechanism is being discussed. Copyright © 2016 VBRI Press.
Vinamrita Singh; Vishal Sharma; Swati Arora; Manoj Arora; R. P. Tandon
Abstract
In the present work, the degradation mechanism of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells has been studied under variable environmental conditions, i.e., in air and under vacuum. It was observed that the absorption for P3HT:PCBM film kept under normal atmospheric conditions decreased slightly after 350 ...
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In the present work, the degradation mechanism of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells has been studied under variable environmental conditions, i.e., in air and under vacuum. It was observed that the absorption for P3HT:PCBM film kept under normal atmospheric conditions decreased slightly after 350 hours of fabrication. When these films were kept under vacuum, no change in the absorption intensity was observed. However, when the P3HT:PCBM films with PEDOT:PSS layer were studied, an increase in absorption spectra was observed both under air and vacuum. This strongly suggests that the presence of hygroscopic PEDOT:PSS adversely affects the optical properties of thin films and hence the solar cells. The AFM images of the films after degradation showed presence of microscopic holes and mico-sized particles. The decrease in mobilities with time was also less when the devices were kept in vacuum. This suggests that the decrease in mobility is dependent on the decreasing crystallinity of P3HT:PCBM films as observed by XRD data and due to diffusion of impurities. The fall in efficiency of fabricated devices is higher for device exposed to the environment as compared to the fall for device kept under vacuum. These analyses give insight into the possible degradation pathways and help in eradicating the factors responsible for short shelf-life of organic solar cells, thus enabling better device performance in future.
Abhishek K. Bhardwaj; Abhishek Shukla; S. C. Singh; Kailash N. Uttam; Gopal Nath; Ram Gopal
Abstract
Green synthesis of nanoparticles (NPs) from biological constituents extracts have emerged as potential methods for the fabrication of metallic NPs. In the present study, Cuprous oxides hallow microspheres (Cu2O-HMs) have been synthesized using D. carota pulp waste extract (CPWE). This Cu2O hollow microsphere ...
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Green synthesis of nanoparticles (NPs) from biological constituents extracts have emerged as potential methods for the fabrication of metallic NPs. In the present study, Cuprous oxides hallow microspheres (Cu2O-HMs) have been synthesized using D. carota pulp waste extract (CPWE). This Cu2O hollow microsphere (Cu2O-HMs) synthesis is environmental friendly, at room temperature. The aqueous copper ions are reduced into Cu2O-NPs, when these ions interact with active reducing constituents of CPWE and very little amount of sodium hydroxide for enhancing rate of reaction. The Cu2O-NPs have been characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Transmission electron microscopy (TEM). XRD measurements contain average size of Cu2O-NPs are approx 12 nm which is responsible to form Cu2O-HMs. UV-VIS spectra show that the surface Plasmon resonance peak of copper is observed at 490 nm. FTIR measurements indicate the presence of different reducing constituents in D. carota extract which is responsible for reducing and capping bioreduced Cu2O-HMs. TEM measurement shows that most Cu2O-HMs are spherical in shape and are responsible to form microsphere and nanotubes. Antibacterial activity of Cu2O-HMs tested on S. aureus shows a comparable zone of inhibition. These interesting results may be applicable for the cost-effective, environmental friendly, surface disinfectant and biomedical fields. Copyright © 2017 VBRI Press.
Snehal L. Kadam; Pallavi M.Padwal; Sagar M.Mane; Shrinivas B.Kulkarni
Abstract
MnO2 metal oxide electrode material is synthesized by simple electrodeposition method on stainless steel substrate. The crystal structure and surface morphological characterizations of the obtained electrode are carried out by using X-ray diffraction (XRD) technique and Field Emission-Scanning Electron ...
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MnO2 metal oxide electrode material is synthesized by simple electrodeposition method on stainless steel substrate. The crystal structure and surface morphological characterizations of the obtained electrode are carried out by using X-ray diffraction (XRD) technique and Field Emission-Scanning Electron Microscopy (FE-SEM) respectively. The FE-SEM micrographs show highly porous well developed interconnected uniform nanosphere like morphology. The electrochemical properties of MnO2 electrode like Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) etc are studied in a 0.5 M Na2SO4 solution as electrolyte. The maximum specific capacitance is 543 F/g at scan rate 5 mVs-1 obtained from cyclic voltammetry (CV). The electrochemical stability of MnO2 electrode is investigated using cyclic voltammetry for 1000 cycles. The MnO2 electrode exhibits good cycling stability for 1000 cycles at scan rate100 mVs-1. The values of energy density and power density of MnO2 electrode material obtained from Galvanostatic charge-discharge studies. From all the electrochemical properties of MnO2 electrode, it indicates that it will be promising electrode material for supercapacitor application.
Pooja Saini; Khobaib .; Prikshit Gautam; Manjari Singh; Ram P. Tandon; S. P. Singh; Ajit K. Mahapatro
Abstract
This work explains the functionalization of polyallylamine (PAA) on the graphene oxide (GO) sheets following a chemical route. The resulting GO-PAA complex is characterized by using various imaging and analytical tools. In the Raman spectroscopy for both the GO and GO-PAA, the appearance of D and G characteristic ...
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This work explains the functionalization of polyallylamine (PAA) on the graphene oxide (GO) sheets following a chemical route. The resulting GO-PAA complex is characterized by using various imaging and analytical tools. In the Raman spectroscopy for both the GO and GO-PAA, the appearance of D and G characteristic bands correspond to the sp2 and sp3 contents, respectively, in the carbon sheets. The observation of lowered D/G peak intensity ratio of these peaks from 1.3 for GO to 1.1 for GO-PAA indicates the lowering of the D favored sp2 content in the GO sheet after PAA functionalization. In the Fourier transform infra-red spectroscopy, the disappearance of the vibrational modes for ketone and carboxyl groups, and appearance of the amine (-NH) group confirms the chemical interaction of GO and PAA triggered with the -NH group of PAA interacting with the oxygen contained hydroxyl, epoxy, and carboxylic groups of the GO sheets to form the GO-PAA complex. Scanning electron microscopy imaging indicates opaque layers with no distinction of flakes after PAA functionalization. Copyright © 2017 VBRI Press
Ram J. Sengwa; Shobhna Choudhary
Abstract
Dielectric dispersion and relaxation behaviour of aqueous solution grown polymeric nanocomposite films consisting of poly(vinyl alcohol) (PVA) and alumina (Al2O3) (PVA–x wt% Al2O3 (x = 0, 1, 3 and 5)) have been studied in the frequency range from 20 Hz to 1 MHz by employing dielectric relaxation ...
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Dielectric dispersion and relaxation behaviour of aqueous solution grown polymeric nanocomposite films consisting of poly(vinyl alcohol) (PVA) and alumina (Al2O3) (PVA–x wt% Al2O3 (x = 0, 1, 3 and 5)) have been studied in the frequency range from 20 Hz to 1 MHz by employing dielectric relaxation spectroscopy (DRS). It is found that at constant frequency, the real part of complex permittivity increases nonlinearly with the increase of Al2O3 nanoparticles concentrations in the PVA matrix, whereas it decreases with increase of frequency at constant concentration of Al2O3. The temperature dependent investigation on PVA–3 wt% Al2O3 film reveals that the dielectric properties increase with the increase of temperature confirming its thermally activated dielectric behaviour. The ac electrical conductivity of the nanocomposites increases and the impedance values decreases with the increase of frequency which are moderately affected by Al2O3 concentrations(x = 0 to 5 wt%) and temperatures (30 to 60 °C). The dc conductivity and relaxation time of PVA chain segmental motion of the nanocomposites obey the Arrhenius behaviour. The X-ray diffraction (XRD) study reveals that the crystallite size and amorphous phase of PVA increase with the increase of Al2O3 concentration in the PVA–Al2O3 nanocomposites. Results of this study confirm the suitability of PVA–Al2O3 nanocomposite materials as tunable nanodielectric for their use as insulator and substrate in the fabrication of microelectronic devices operated at audio and radio frequencies. Copyright © 2017 VBRI Press.
Vishal K. Chakradhary; Azizurrahaman Ansari; M.J. Akhtar
Abstract
Material synthesis is a scientific art, considering all parameters and conditions in practical view and applying them in an experiment. Properties of synthesized material can be tuned further by technically playing with concerned parameters individually. In this work, a one to one relation between the ...
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Material synthesis is a scientific art, considering all parameters and conditions in practical view and applying them in an experiment. Properties of synthesized material can be tuned further by technically playing with concerned parameters individually. In this work, a one to one relation between the formation of cubic spinel ferrite structure with stable phase and morphology has been established, and corresponding changes in the magnetic properties are investigated with temperature. Heat treatment method is adopted for the preparation of nanoparticles of cobalt doped nickel ferrite Ni1-xCoxFe2O4 (x=0.5) and characterized by XRD, FESEM, TGA and VSM. Initially, as synthesized powder sample shows amorphous and weak ferromagnetic nature (Ms = 0.04 emu/g, Hc = 92.42 Oe), but heat treatment at 400ºC exhibits signature of phase formation with irregular particle shape and ferromagnetic (Ms = 6.62emu/g, Hc = 460 Oe) behaviour. On further heating upto 600ºC, the nanoparticles of Ni1-xCoxFe2O4 (x=0.5) is formed with stable cubic spinel crystal structure (lattice constant a=8.35452Å) and enhanced magnetic properties (Ms=8.24emu/g, Hc=1955Oe). Due to higher coercivity obtained of Ni1-xCoxFe2O4 (x=0.5) nanoparticles, it may be useful material in the production of data storage devices, permanent magnet, parts of electronic circuits and also in stealth technology.
Shrisha B V; Shashidhara Bhat; Parvathy Venu M; Dushyant Kushavah; K Gopalakrishna Naik
Abstract
Zinc Oxide (ZnO) nanowires (NWs) were grown on p-silicon (p-Si) substrates coated with around 10 nm thick metal films of Au, Al and Cu using vapor phase transport growth method. The effect of these metal catalysts and the substrate temperatures on the morphologies of ZnO NWs were studied using ...
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Zinc Oxide (ZnO) nanowires (NWs) were grown on p-silicon (p-Si) substrates coated with around 10 nm thick metal films of Au, Al and Cu using vapor phase transport growth method. The effect of these metal catalysts and the substrate temperatures on the morphologies of ZnO NWs were studied using field emission scanning electron microscopy (FESEM). The growth of ZnO NWs with high aspect ratio was observed at substrate temperatures above 600 oC. The structural and optical properties of the as grown ZnO NWs were characterized using X-ray diffraction (XRD) and photoluminescence spectroscopy (PL) techniques, respectively. XRD study revealed that, the grown samples possess hexagonal wurtzite structure with (002) preferential orientation. The metal droplets were observed at the tips of ZnO NWs when Au was used as catalyst, but not in the case of Al and Cu. The PL spectra exhibited two peaks, one in the UV region and the other in the visible region. The low-cost Al and Cu metal catalyst assisted growth of metal contamination-free ZnO NWs may be suitable for the device applications.
M. Kanakadurga; S. R. Murthy; Arya Das; Rakesh K. Sahoo; Saroj K. Singh
Abstract
ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated ...
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ZnO nano-platelets have been prepared using a high pressure reactor via hydrothermal route. The as-formed fine platelets morphology of the as-synthesized powder was confirmed from the scanning electron microscopy (SEM) images. The elemental analysis using energy dispersive X-ray (EDAX) analysis indicated the presence of Zn, O, Na and Cl which confirms the presence of ZnO as major and NaCl as the minor phase. The precipitation of this minor phase after growth and catalytic induction in nano-platelet (NP) morphology during growth has been elucidated. The electrochemical performance of this as-synthesized powder is quite promising. Additionally, the effect of this minor NaCl phase in changing the ionic equilibrium of the electrolyte in capacitance measurement has been analyzed.
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.
Hetal Boricha; Zalak Joshi; Davit Dhruv; K.N. Rathod; Keval Gadani; D.D. Pandya; Sanjay Kansara; C.M. Thaker; S. Rayaprol; P.S. Solanki; N.A. Shah
Abstract
In this communication, we report the results of the studies on structural and transport properties of monovalent Na+ doped La1–xNaxMnO3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements ...
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In this communication, we report the results of the studies on structural and transport properties of monovalent Na+ doped La1–xNaxMnO3 (LNMO; x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) manganites synthesized by conventional ceramic method. X-ray diffraction (XRD) and Rietveld refinements reveal the single phasic nature of LNMO manganites without any detectable impurity within the measurement range. Temperature dependent resistivity, under different applied magnetic fields, has been performed on LNMO samples. Samples understudy exhibit metal to insulator (semiconductor) transition at temperature TP which is strongly influenced by the substitution of Na+ at La3+ site. r – T plots also exhibit resistivity upturn behavior at low temperature well below 40K under all the applied fields. Variation in TP and resistivity has been discussed in the context of the competition between the transport favoring tolerance factor and zener double exchange (ZDE) mechanism and transport degrading Jahn–Teller (JT) and size variance effects. In order to understand the mechanisms responsible for the charge transport in metallic and semiconducting regions and to explore the possible electronic processes responsible for the observed low temperature resistivity minima in all the presently studied LNMO manganites, various models have been employed. It has been found that VRH mechanism gets successfully fitted to the resistivity data in the semiconducting region while ZDE polynomial law is responsible for the charge conduction in metallic region for all the presently studied LNMO samples. A strong dependence of activation energy on the Na+ – content as well as applied magnetic field has been discussed in the context of variation and interrelations between the structural parameters. Charge conduction in metallic region has been discussed in the light of electron–phonon interactions which is influenced by the Na+ – content and applied magnetic field. Electrostatic blockade model has been employed to understand the low temperature resistivity minima behavior. Blocking energy for the charge carriers shows a dependence on the magnetic energy provided to the charge carriers. Present study can be useful to understand and to control the charge conduction in the manganites and hence to design the manganite based thin film devices for various spintronic applications.
Shiva Sharma; Pratima Chauhan; Shahid Husain
Abstract
Mn2O3 nanoparticles have been synthesized using chemical co-precipitation method. The as synthesized nanoparticles were characterized by X-ray diffractometer (XRD), UV-Visible spectrophotometer (UV-Vis) and Fourier Transform Infra-Red (FTIR) spectrophotometer method. The results indicate that synthesized ...
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Mn2O3 nanoparticles have been synthesized using chemical co-precipitation method. The as synthesized nanoparticles were characterized by X-ray diffractometer (XRD), UV-Visible spectrophotometer (UV-Vis) and Fourier Transform Infra-Red (FTIR) spectrophotometer method. The results indicate that synthesized Mn2O3 nanoparticles possessed crystallites having sizes 12.56 nm and 11.90 nm with cubic and orthorhombic structures respectively. The two samples are named as M1 and M2. The gas response of both the samples was investigated for different concentrations of NH3 gas at room temperature. Sample M2 based thick film sensor showed enhanced sensing performance in comparison to sample M1. This is attributed to smaller crystallite size of sample M2. The sample M2 based sensor showed the response of 67.1% with the response and recovery times 65 and 71 sec respectively. The fabricated nanoparticles show promising use as room temperature NH3 sensors.
