Rashmi Singh; Puneet Jain; Naresh Kumar; Pramod Kumar
Abstract
Thin films of Co2MnSi are grown on n-doped Si (100) and SiO2 (100) substrates by RF sputtering. The deposition time to grow the films is varied, once for ten minutes and another for an hour at a particular substrate temperature 600oC and keeping all the other parameters same. The Co2MnSi thin films deposited ...
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Thin films of Co2MnSi are grown on n-doped Si (100) and SiO2 (100) substrates by RF sputtering. The deposition time to grow the films is varied, once for ten minutes and another for an hour at a particular substrate temperature 600oC and keeping all the other parameters same. The Co2MnSi thin films deposited on Si and SiO2 are crystalline irrespective of the deposition time. The grains were round in the thin films deposited for 10 minutes and these grains are more consistently interconnected in the films deposited for 1 hour. This is supported by the surface roughness data from AFM. The rms roughness is found to be 4.82nm for Si for 10 minutes and 2.50nm for Si for 1 hour deposition that was observed over an area of 3µm2. Copyright © 2017 VBRI Press.
Dinesh Selvakumaran; Anandan Manickam; Gopalakrishnan Ravi; Gohulkumar Muthusamy; Barathan Seshatri
Abstract
Highly crystalline Mg2SnO4 nanocubes were successfully synthesized using a facile hydrothermal method. Further activated carbon was loaded with Mg2SnO4 nanoparticles in order to enhance the photocatalytic performance. Photocatalytic performance of Mg2SnO4 nanocubes and activated carbon loaded Mg2SnO4 ...
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Highly crystalline Mg2SnO4 nanocubes were successfully synthesized using a facile hydrothermal method. Further activated carbon was loaded with Mg2SnO4 nanoparticles in order to enhance the photocatalytic performance. Photocatalytic performance of Mg2SnO4 nanocubes and activated carbon loaded Mg2SnO4 nanocomposites were examined by methyl green and methylene blue dye degradation under the exposure of UV light. However, results suggest that activated carbon loaded Mg2SnO4 nanocomposites has significantly enhanced the photocatalytic performance over Mg2SnO4 nanocubes. It is assumed that better photocatalytic activity is caused by the higher specific surface area of activated carbon loaded Mg2SnO4 nanocomposites. Furthermore, cyclic voltammetry was used to analyze the electrochemical properties of the samples. Results indicate that activated carbon significantly enhanced the electrochemical properties of Mg2SnO4 nanoparticles. Copyright © VBRI Press.
Pragya Pandit; Pargin Bangotra
Abstract
In this paper we investigate the effect of lanthanum doping on structural, dielectric and electrical properties of lead magnesium niobate - lead titanate, 0.65Pb(Mg1/3Nb2/3O3)- 0.35PbTiO3 (x=0, 0.02, 0.05) ferroelectric ceramics. Dielectric and AC impedance spectroscopic measurements were ...
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In this paper we investigate the effect of lanthanum doping on structural, dielectric and electrical properties of lead magnesium niobate - lead titanate, 0.65Pb(Mg1/3Nb2/3O3)- 0.35PbTiO3 (x=0, 0.02, 0.05) ferroelectric ceramics. Dielectric and AC impedance spectroscopic measurements were carried out on pure and lanthanum doped PMN/PT ceramics over a wide temperature (30o- 450o C) and frequency interval (10 Hz-1 MHz). Pure and lanthanum doped Pb1-xLax[(Mg1+x/3Nb2-x/3)0.65Ti0.35(1-x/4)]O3, (x=0, 0.02, 0.05) ceramics were prepared by solid state reaction route using columbite precursor method. X-ray diffraction revealed tetragonal (P4mm) phase for pure PMN/PT ceramics and transition to pseudo cubic phase (Pm3m) was observed with increased lanthanum doping. The dielectric response of the lanthanum modified PMN/PT ceramics was interpreted in terms of modified curie weiss law. Modulus spectroscopy revealed the deviation of dielectric behavior from ideal Debye behaviour. Activation energies calculated from dielectric relaxation and modulus spectroscopy suggested that charge transport processes are due to oxygen ion hopping.The AC conductivity of the PMN/PT ceramics initially increased for 2 mol% of lanthanum doping followed by a subsequent decrease with further 5 mol% of lanthanum doping. The value of the activation energies calculated from the temperature dependance of ac conductivity was in the range from 1.20-1.48 ev which is due to doubly ionized oxygen vacancies. The overall structural, electrical and dielectric behaviour of Pb1-xLax[(Mg1+x/3Nb2-x/3)0.65Ti0.35(1-x/4)]O3, (x=0, 0.02, 0.05) ceramics is correlated to the relaxor nature induced by lanthanum doping.
M. Prathap Kumar; G.A. Suganya Josephine; A. Sivasamy
Abstract
Exploration of semiconductors in the field of photocatalysis plays a crucial role in energy and environmental remediation in particular oxidation/reduction of toxic organic contaminants from water and wastewater. The present research work aims on synthesis of pristine CeO2nanoparticles by precipitation ...
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Exploration of semiconductors in the field of photocatalysis plays a crucial role in energy and environmental remediation in particular oxidation/reduction of toxic organic contaminants from water and wastewater. The present research work aims on synthesis of pristine CeO2nanoparticles by precipitation method and was thoroughly characterized by Fourier Transform Infrared spectroscopy, X-ray Diffraction, UV-vis-Diffuse Reflectance Spectroscopy, High Resolution Scanning Electron Microscopy, EDAX and Electron Spin Resonance techniques. The band gap energy (Ebg) was found to be 3.19 eV. The synthesized nanomaterials showed spherical morphology and the particles size ranged from 50-93 nm. The insitu generation of ·OH radicals was confirmed from ESR studies. The synthesized CeO2nanospheres was evaluatedin photocatalytic oxidation of an azo dye Acid orange 10 under Ultraviolet and visible light irradiations. Experimental studies such as pH, catalyst amount and effect of initial dye concentration were also studied. Kinetic studies indicate the photo reaction follows pseudo-first order rate equation. The photocatalytic oxidation of dye molecules were monitored by UV-visible spectroscopy and COD analyses. The level of chemical oxygen demand (COD) of the photodegraded samples decreases in both the photocatalytic systems indicating that dye molecules readily degraded under present experimental conditions.Effect of electrolytes like MgSO4,KCl, Na2CO3 and NaHCO3 were also investigated to check interference of inorganic anions on photocatalytic oxidation of dye molecules using CeO2 nanospheres. Finally, the prepared catalyst was checked for its reusability and the photocatalyst exhibited better photocatalytic activity evenafter three cycles of regeneration.Copyright © VBRI Press.
Sudhanshu Kanaujia; Sanjay K. Singh; Bharat Singh
Abstract
A comparative study was done for removal of fluoride by Al (III) modified Clinoptilolite (AC) and Carbonised Punica Granatum Carbon (CPGC) through batch techniques. The fluoride removal performance of both adsorbents AC and CPGC was evaluated as a function of the initial concentration, adsorbent ...
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A comparative study was done for removal of fluoride by Al (III) modified Clinoptilolite (AC) and Carbonised Punica Granatum Carbon (CPGC) through batch techniques. The fluoride removal performance of both adsorbents AC and CPGC was evaluated as a function of the initial concentration, adsorbent dose, contact time and pH. The equilibrium was attained at 90 and 75 minutes for AC and CPGC adsorbents, but percentage of removal was 76 and 65 for AC and CPGC respectively. The maximum adsorption of fluoride was found at pH 6.95 and 5.92 for AC and CPGC adsorbent respectively. The system followed the Freundlich isotherm model for both AC and CPGC with adsorption capacity 0.24 mg/g and 0.4 mg/g respectively. Copyright © 2018 VBRI Press.
Vipin Jain; Anil Kumar; Ajay Dhar
Abstract
Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, ...
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Graphene possesses excellent properties such as, high Young’s modulus (1 TPa), high fracture strength (~125 GPa) and extreme thermal conductivity (~5000 W/m/K), therefore, can serve as an ideal reinforcement material for the metal based High Tech structural nanocomposites. In the present work, a novel chemical synthesis method has been adopted for the in-situ synthesis of aluminium-graphene (Al-Gr) nanocomposite powders with varying compositions using graphene oxide (GO) as the precursor. The pure aluminium powder was initially cryomilled to refine the crystallite size. Subsequently, Al-reduced graphene (Al-Gr) nanocomposite powders were synthesized employing different volume proportions of GO (referred as 0.5, 2, 4, and 6 ml) dispersed in deionized water. The synthesized nanocomposite powders were ball milled followed by consolidation using spark plasma sintering under the optimized conditions. The nanocomposite powder as well as SPSed samples were characterized using X-ray diffraction (XRD), Raman Spectroscopy and electron microscopy. Scanning electron microscopy (SEM) studies of nanocomposite powders have depicted wrinkled structure typical of reduced graphene. Raman spectra have shown regular D, G, 2D and D+G bands and a modulated 2D peak having intensity significantly less than the G peak was observed for the nanocomposite powders confirming multilayered graphene is synthesized. The graphene wrinkles were determined in the size of 100 nm or more. Microhardness of SPS sintered nanocomposites is found progressively increased with the increasing content of reduced graphene with up to 58% improvement over pure Al was observed for the maximized GO content depicting potential for energy efficient high strength applications. The synthesized Al-graphene nanocomposites are novel in terms of an innovative, indigenously developed and scalable to bulk synthesis approach based on in-situ chemical synthesis route adopted. Copyright © 2017 VBRI Press.
Sitakshi Gupta; Chhaya Ravikant
Abstract
Nowadays, gas sensors are fast becoming an imperative part of modern life with extensive applications in domestic safety, environmental monitoring, industrial process control, public security, medical applications and chemical warfare assessment amongst many others. The detection of minor gas leaks has ...
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Nowadays, gas sensors are fast becoming an imperative part of modern life with extensive applications in domestic safety, environmental monitoring, industrial process control, public security, medical applications and chemical warfare assessment amongst many others. The detection of minor gas leaks has been a challenging area of research, particularly in view of the hazards to human health and safety posed by toxic gases like NO2, NO, CO, NH3 etc and combustible gases like methane, hydrogen gas and some volatile organic compounds. Thus it is imperative to evolve and employ simple yet reliable gas sensing mechanisms with optimum response and selectivity towards even low concentration of analyte gas at room temperature. Most of the conventional gas sensors are based on metal-oxide semiconductors which are low-cost, exhibit good sensitivity and fast response/recovery. Zinc oxide is one such n-type semiconducting oxide, which has been widely studied for gas sensing response due to its ease of fabrication, high sensitivity and environment-friendly nature. However, the operating temperature of such sensors is usually high (>200°C) owing to the wide band-gap (3.37 eV) and high electrical resistance (kΩ-MΩ), which limits their practical utilization. In order to be used in hazard monitoring and home/workplace safety, the gas sensors need to be sensitive to gas exposure in mild operating conditions. As an alternative, more recently, graphene and its derivatives like pristine graphene (PG), reduced graphene oxide (rGO) etc. have been studied for sensing applications owing to their exceptional electronic and physical properties such as high carrier mobility at room temperature, good thermal stability, high mechanical strength, ballistic conductivity and large specific surface area. These sensors show high sensitivity at low operating temperatures (down to room temperature) towards low concentrations of analyte gas. However most of these rGO based sensors exhibit relatively longer response/recovery times than metal-oxide based gas sensors. Hence, nanocomposites formed by hybridizing graphene or its derivatives with metal-oxide nanoparticles are being explored as gas sensing materials. Combining reduced graphene oxide with zinc oxide to form hybrid nanostructures is particularly interesting because not only do they display the individual properties of the metal oxide NPs (faster response/recovery times) and of graphene (high electronic conductivity leading to efficient room temperature gas response), but may also have synergistic effects leading to better sensitivity as a gas sensing material. Here we present a review of the recent progress in rGO-ZnO nanocomposites based gas sensors. Copyright © 2018 VBRI Press.
Bikash Mandal; I. Basumallick; Susanta Ghosh
Abstract
Highly dispersed, porous and nano-sized FePO4 have been synthesized by a facile aqueous and alcoholic medium for their application as cathode in rechargeable lithium batteries. Various dispersing templates in association with suitable solvents are used to introduce porosity and dispersive nature among ...
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Highly dispersed, porous and nano-sized FePO4 have been synthesized by a facile aqueous and alcoholic medium for their application as cathode in rechargeable lithium batteries. Various dispersing templates in association with suitable solvents are used to introduce porosity and dispersive nature among the particles and to reduce the size of the particles. Characterization with FTIR, powder XRD and SEM suggests the formation of less crystalline, pure FePO4 with high surface area and high porosity. Cyclic voltametry has been employed to test the intercalation behaviour of lithium ions and confirms the reversible nature of the material. The role of the dispersing template for the material growth and the electrochemical performances of the synthesized FePO4 as cathode in lithium battery have been discussed. It is found that poly(styrene-co-divinylbenzene) as the dispersing agent produces highly dispersed material with highest discharge capacity of 138 mAh.g-1. Copyright © 2017 VBRI Press.
Shahjad .; Ranoo Bhargav; Dinesh Bhardwaj; Asit Patra
Abstract
Currently significant progress has been made for the small molecules, indeed, achieved comparable performance compared to polymer in electronic devices mainly due to the many advantages of small molecules over the polymers. Designing better small molecules for electronic applications are required a comprehensive ...
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Currently significant progress has been made for the small molecules, indeed, achieved comparable performance compared to polymer in electronic devices mainly due to the many advantages of small molecules over the polymers. Designing better small molecules for electronic applications are required a comprehensive understanding of the structure-properties relationship and the factors affecting it. Valuable information can be generated directly toward understanding by systematically theoretical and experimental studies (band gap, HOMO, LUMO energy levels and geometry). Hybrid density functional B3LYP level of theory is a very good method for predicting the reliable geometry, electronic structure and properties of conjugated systems. In the present work, we have calculated the band gaps, highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) and geometry of a series of small molecules based on oligothiophene, benzodithiophene and dithienosilole unit using the hybrid density functional (B3LYP/6-31G(d)) level of theory and correlated with experimental values. The study provides details for the effect of the extended conjugation, two-dimension conjugation, substitution on geometry, HOMO, LUMO and band gaps of the small molecules. Copyright © 2017 VBRI Press.
S Sandeep; S SanthoshA; N Kumara Swamy; G S Suresh; J S Melo
Abstract
In the present work, we have biosynthesized silver nanoparticles (AgNPs) using leaf extract of Euphorbia geniculata and successfully deposited them onto the polyvinyl pyrolidone (PVP) modified graphite electrode (Gr/PVP). The resulting electrode is used as a matrix for the immobilization of glucose oxidase ...
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In the present work, we have biosynthesized silver nanoparticles (AgNPs) using leaf extract of Euphorbia geniculata and successfully deposited them onto the polyvinyl pyrolidone (PVP) modified graphite electrode (Gr/PVP). The resulting electrode is used as a matrix for the immobilization of glucose oxidase (GOx) enzyme. The immobilized electrode (Gr/PVP/AgNPs/GOx) is characterized by scanning electron microscopy and its performance is evaluated and optimized using cyclic voltammetry and differential pulsevoltammetrictechniques. Under neutral pH conditions, at room temperature, the developed Gr/PVP/AgNPs/GOx sensor showed excellent electrocatalytic activity towards the oxidation of glucose. Further, it is used for the determination of glucose in the concentration range of 0.1-7 mM with a detection limit of 0.15 µM and sensitivity of 29.72 µA mM-1 cm-2. In addition, the response of GOx biosensor is found to be uninfluenced by some common possible interferents. The findings of present work are significant and imply potential applications for biosynthesized AgNPs as effective, non-toxic biocompatible sensor fabrication materials. Copyright © 2018 VBRI Press.
Sharmistha Anwar; Shahid Anwar
Abstract
Present work is focused on various properties of thermally annealed tungsten nitride (WN) film. Tungsten nitride thin films on silicon (100) substrates were deposited via reactive magnetron sputtering technique. Initially Ar/N2 flow ratio was optimized by varying N2 gas flow between 5 to 25 sccm. 20:5 ...
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Present work is focused on various properties of thermally annealed tungsten nitride (WN) film. Tungsten nitride thin films on silicon (100) substrates were deposited via reactive magnetron sputtering technique. Initially Ar/N2 flow ratio was optimized by varying N2 gas flow between 5 to 25 sccm. 20:5 (Ar:N2) was found to be the best for W2N phase formation. Using optimized condition, a set of WN deposited and then annealed at different temperatures i.e. 200°C, 400°C and 600°C for two hours each. Various characterizations have been done using X-ray diffraction, four probe resistivity and nano-indentation test. XRD results suggest formation of pure W2N crystalline phase of the films with face centered cubic structure. The resistivity result shows the decrease of resistivity value with increase in annealing temperature. Nano-indentation results showed hardness and elastic modulus values at 5mn load does not vary much with annealing at different temperatures. Structural, mechanical and electrical studies showed that the samples were stable up to 600°C. Thus, tungsten nitride thin films will contribute as a material suitable for long time exposure at elevated temperature for application of cutting tools. Copyright © 2017 VBRI Press.
Jan Trejbal; Tereza Valentová; Zdeněk Prošek
Abstract
This work focuses on a surface modification of polypropylene micro-fibers having 18 μm in diameter and 12 mm in length by means of the cold low-pressure oxygen plasma treatment. The main goal is to change fiber surface properties from hydrophobic to hydrophilic and from smooth to slightly ...
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This work focuses on a surface modification of polypropylene micro-fibers having 18 μm in diameter and 12 mm in length by means of the cold low-pressure oxygen plasma treatment. The main goal is to change fiber surface properties from hydrophobic to hydrophilic and from smooth to slightly roughened and thus to ensure a strong adhesion of their surfaces with a cement matrix. As a proper indicator of realised modifications, scanning electron microscopy (an assessment of surface roughening) and a wettability measurement with demineralized water were done. Moreover, in order to establish a time-dependent stability of the chemical changes onto fiber surfaces, the wettability measurement was repeated immediately after the treatment and with a time lag equal to 1, 7 and 30 days, when fibers were exposed to standard atmospheric conditions. To asses a rate of an adhesion between fibers and the cement matrix, mechanical four-point bending tests of prismatic cement samples (CEM I 42.5 R, w/c 0,4, dimensions 40×40×160 mm) reinforced with both reference and treated fibers were performed. SEM revealed slightly roughened fiber surfaces after plasma modifications. The treated fiber wettability with water increased almost twice, compared to reference fibers. Nevertheless, the wettability fast decreased to reference values. Copyright © 2018 VBRI Press.
Praveenkumar R. Upadhyay; Vivek Srivastava
Abstract
Stable, well dispersed and agglomeration free Ru metal doped TiO2 nanoparticles were produced by a sol gel method (with and without ionic liquid reaction medium). Such unique physiochemical properties of Ru-TiO2-IL catalyst were utilized as catalysts for CO2 hydrogenation reaction in task specific ionic ...
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Stable, well dispersed and agglomeration free Ru metal doped TiO2 nanoparticles were produced by a sol gel method (with and without ionic liquid reaction medium). Such unique physiochemical properties of Ru-TiO2-IL catalyst were utilized as catalysts for CO2 hydrogenation reaction in task specific ionic liquid medium. Low catalysts loading, moisture/air stability, high selectivity, easy catalyst synthesis protocol as well as stress-free reaction condition along with 5 times catalysts recycling are the major outcomes of the proposed report. Copyright © 2017 VBRI Press.
Sourav Das
Abstract
The impact toughness of closed-cell aluminum foam with various densities was investigated using Charpy impact. The impact load history revealed an elastic region followed by a rapid load drop region. The peak load and impact toughness of aluminum foam increase exponentially with density. The power exponents ...
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The impact toughness of closed-cell aluminum foam with various densities was investigated using Charpy impact. The impact load history revealed an elastic region followed by a rapid load drop region. The peak load and impact toughness of aluminum foam increase exponentially with density. The power exponents for the impact toughness test are greater than that of the compressive test. Fracture analysis indicated a mixed-rupture mode of quasi-cleavage and small shallow dimples. It can be attributed to the complex state of stress of notched specimens and elevated impact velocity under impact loading. Copyright © 2018 VBRI Press.
Kate Kotlhao; Moloko D.T. Madiseng; Fanyana M. Mtunzi; Vusumzi E. Pakade; Sekomeng J. Modise; Neelan Laloo; Michael J. Klink
Abstract
Three different types of nanoparticles were synthesised in this study, viz silver (Ag), zinc oxide (ZnO) and titanium dioxide (TiO2) using different chemical methods. These materials were then characterised using Transmission Electron Microscopy (TEM), Fourier Transform Infra-Red Spectroscopy (FTIR), ...
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Three different types of nanoparticles were synthesised in this study, viz silver (Ag), zinc oxide (ZnO) and titanium dioxide (TiO2) using different chemical methods. These materials were then characterised using Transmission Electron Microscopy (TEM), Fourier Transform Infra-Red Spectroscopy (FTIR), Ultraviolet Visible Spectroscopy (UV-Vis) and Thermal Gravimetric Analysis (TGA). The materials were also tested for anti-bacterial activity. TEM showed that the particles were in the nano-size range (1 – 100 nm). FTIR and UV-Vis Spectroscopy showed the different absorption bands of the synthesised nanoparticles, respectively. Silver nanoparticles showed greater antibacterial activity against several bacteria than titanium dioxide and zinc oxide nanoparticles. The highest inhibition was observed for Klebsiella pneumoniae. The results showed that antimicrobial activity of nanoparticles increases with increasing concentration of the nanoparticles. Copyright © 2017 VBRI Press.
Andrea Di Schino; Paolo Emilio Di Nunzio
Abstract
Following the high cost of Mo and other alloying elements, many attempts are being carried out aimed to improve the hardenability of high thickness forged components without increasing their price. In this work the effect of B is examined on laboratory scale. In particular, two ingots have been cast ...
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Following the high cost of Mo and other alloying elements, many attempts are being carried out aimed to improve the hardenability of high thickness forged components without increasing their price. In this work the effect of B is examined on laboratory scale. In particular, two ingots have been cast in a pilot plant, with boron addiction. Boron as been added in a protected steel chemical composition, so to be effective in terms of hardenability. Materials were then hot rolled and cooled favoring the formation of a microstructure typical of that of forged components. Results on the material are compared to that of a standard steel in terms of hardenability. Copyright © 2018 VBRI Press.
P Swapna; S Venkatramana Reddy
Abstract
Pure and (Ni, Al) co-doped ZnO nanostructures are prepared lucratively by chemical co-precipitation process at room temperature by means of poly ethylene glycol (PEG) as stabilizing agent. Zinc acetate dehydrate and potassium hydroxide are used as preliminary materials. The synthesized samples are characterized ...
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Pure and (Ni, Al) co-doped ZnO nanostructures are prepared lucratively by chemical co-precipitation process at room temperature by means of poly ethylene glycol (PEG) as stabilizing agent. Zinc acetate dehydrate and potassium hydroxide are used as preliminary materials. The synthesized samples are characterized by XRD, Scanning Electron Microscopy (SEM) with EDS, Photoluminescence (PL), and Transmission Electron Microscopy (TEM). X-RAY Diffraction pattern reveals that both pristine and co-doped samples acquire hexagonal wurtzite crystal structure with no secondary phase and nonappearance of secondary phase indicates the nonexistence of impurities. SEM descriptions illustrate that all the particles are almost spherical shape and EDAX analysis reveals that doing well incorporation of dopants and lack of impurities. PL spectrum shows that all the samples containing peaks in the visible region, which will be defect related peaks. Doped samples show high intensity peaks compared with the undoped sample. TEM images reveals the nature of the particles as spherical and size of nanoparticles are confirmed the XRD data. HRTEM images plainly be evidence for nanoparticles are about 5nm with unambiguous lattice fringes. Copyright © 2018 VBRI Press.
Swati Tapdiya; Ashwani K. Shrivastava; Sarika Singh
Abstract
Manganese substituted Cobalt Ferrite Co1-xMnxFe2O4() nanoparticles were prepared using low temperature chemical co-precipitation method. All the samples were annealed at 900°C for 3 hours. The crystal lattice symmetry and phase purity were performed by X-ray diffraction (XRD). The varying dopent ...
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Manganese substituted Cobalt Ferrite Co1-xMnxFe2O4() nanoparticles were prepared using low temperature chemical co-precipitation method. All the samples were annealed at 900°C for 3 hours. The crystal lattice symmetry and phase purity were performed by X-ray diffraction (XRD). The varying dopent concentration affects the crystalline size, surface morphology and magnetic properties of the cobalt ferrite. The particle sizes are found to be in the range of 29-37 nm. SEM with EDAX examines the morphological and compositional analysis of the nanoparticles. EDAX confirms the presence of Co, Mn, Fe and O. Fourier transform infrared spectroscopy (FTIR) study confirms the formation of spinel ferrite. The saturation magnetization, magnetic remanence and coercive field of CoMn nanoparticles are obtained at room temperature. Saturation magnetization initially increases and then decreases for higher value of dopent, which shows applicability of these materials for recording media and magnetic data storage. Copyright © 2017 VBRI Press.
Samy K. K. Shaat; Hussein A. Dawoud
Abstract
Our novelty for the presented work is to find a simple method to study electric and dielectric properties for samples such as magnetic materials. We focus on prepare and characterize of the ferrites. During the AC measurements, we struggled to use the Lissajous figure. In addition, we have a shortage ...
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Our novelty for the presented work is to find a simple method to study electric and dielectric properties for samples such as magnetic materials. We focus on prepare and characterize of the ferrites. During the AC measurements, we struggled to use the Lissajous figure. In addition, we have a shortage of equipment for measurements. This prompted us to look for a method to be easy to use with simple devices. The Delay-Time measurement method for any two different sinusoidal waves was used to calculate the phase shift ( ) between them using an oscilloscope. The was exercised to resolve the series and the parallel of RC in AC circuit. The phasor diagram of the series and the parallel of RC in AC circuit were plotted. All the main and derived quantities of the AC circuit were calculated, such as the immittances, conductivity and dielectric parameters. The presented method is considered as a simple method comparing to other methods. Thus, it can be replaced the other methods as well as it can be used from the scientists and engineers. Our Master students already used this method and they got good results. This paper is considered to be a preliminary analysis for this simple method and we will develop it. Copyright © 2017 VBRI Press.
Rachna Ahlawat
Abstract
Y2O3 nanocrystallite has been successfully synthesized by sol-gel technique. Y(NO3)3.4H2O and TEOS were used as precursors and obtained powdered form of the oxide. In this study, stepwise annealing process has been performed and obtained almost spherical Y2O3 nanocrystallites. As-prepared sample was ...
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Y2O3 nanocrystallite has been successfully synthesized by sol-gel technique. Y(NO3)3.4H2O and TEOS were used as precursors and obtained powdered form of the oxide. In this study, stepwise annealing process has been performed and obtained almost spherical Y2O3 nanocrystallites. As-prepared sample was annealed at 900°C and their comparison has been studied in detail. Structural investigations of the prepared nanocrystallites were carried out by XRD and TEM. Optical behavior of the sample was investigated using UV-Vis absorption spectra. Also, band gap energy Eg = 5.9 eV has been calculated using Tauc’s plot. It is expected that the studies of these phenomena would open a new vistas of energy conversion devices and high speed optoelectronic instrumentation. Copyright © 2017 VBRI Press.
Martin Wilhelm; Mikael Syväjärvi; Peter J. Wellmann
Abstract
Among the various SiC polytypes, cubic 3C‐SiC is much more difficult to grow in high crystalline quality than the commercially introduced hexagonal 6H‐SiC and 4H‐SiC counterparts. Besides some benefits of 3C‐SiC for transistor applications related to a greater electron mobility and a lower metal‐oxide‐semiconductor ...
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Among the various SiC polytypes, cubic 3C‐SiC is much more difficult to grow in high crystalline quality than the commercially introduced hexagonal 6H‐SiC and 4H‐SiC counterparts. Besides some benefits of 3C‐SiC for transistor applications related to a greater electron mobility and a lower metal‐oxide‐semiconductor interface trap density compared to 4H‐SiC, new potential optoelectronic applications have been introduced very recently. Boron doped 3C‐SiC may act as an ideal candidate for an intermediate band (IB) solar cell material. Aluminum doped p‐type 3C‐SiC could lead to the development of efficient optoelectrochemical water splitting cells. Finally, 3C‐SiC with its various intrinsic point defects has been considered as a suitable candidate for future spintronic‐applications. All these applications will critically depend on further understanding defect behaviour on atomic level. In our study we investigated free standing n‐type and p‐type 3C‐SiC material grown in our lab. Temperature dependent photoluminescence measurements revealed the presence of carbon vacancy related VC and VC-CSi defect transitions in the p‐type materials but not in the n‐type materials. This observation present in as grown 3C-SiC is believed to have significant impact on the optoelectronic applications. Copyright © 2017 VBRI Press.
Mariya Aleksandrova
Abstract
Perovskite materials have become one of the hottest topics in solar energy conversion in recent years. They reached similar efficiency to the polycrystalline silicon solar cells, and also found applications in a variety of fields out of energy harvesting, such as lighting. The main advantage of this ...
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Perovskite materials have become one of the hottest topics in solar energy conversion in recent years. They reached similar efficiency to the polycrystalline silicon solar cells, and also found applications in a variety of fields out of energy harvesting, such as lighting. The main advantage of this class of materials is the ease of processing, a line with the large-scale solution fabrication techniques. Although the technology still faces some challenges related to long-term stability the prospects for commercialization at the beginning of 2021 are much more realistic in comparison with the forecasts released at the end of the previous 2019 year. In this perspective articles analysis of the research and market perspectives of the perovskite solar cells is made.
Sarah Mobley; Kelly Costello; Gray Mullins
Abstract
A common method of constructing foundations for bridges or tall buildings involves deep excavations in which steel reinforcement and fluid concrete are placed while in a submerged state below the ground water table. The excavation stability is achieved by maintaining the fluid level of slurry within ...
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A common method of constructing foundations for bridges or tall buildings involves deep excavations in which steel reinforcement and fluid concrete are placed while in a submerged state below the ground water table. The excavation stability is achieved by maintaining the fluid level of slurry within the excavation well above the ground water table and thus pushes outward against the soil side walls. The most common slurry products are comprised of clay minerals mixed with water to form a thick consistency capable of suspending soil cuttings. More recently, highly engineered polymer slurry products have emerged that, if used properly, far out-perform the traditional mineral slurry products. This paper outlines test results showing the marked performance improvements. Results from concrete to soil bond, steel reinforcement to concrete bond, and corrosion durability tests are presented from multiple research projects all coming to the same conclusion: present methods that use mineral slurry may be unwittingly constructing poor foundation elements, and polymer slurry alternates result in superior end products.
Prashik M. Walke; Jyotsna S. Meshram
Abstract
All Dendrimers are the emerging polymeric architectures known for their defined structure, low polydispersity, nanometric size and high functionality. These nanostructure macromolecules have shown their potential abilities in entrapping and conjugating the high molecular weight hydrophobic or hydrophilic ...
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All Dendrimers are the emerging polymeric architectures known for their defined structure, low polydispersity, nanometric size and high functionality. These nanostructure macromolecules have shown their potential abilities in entrapping and conjugating the high molecular weight hydrophobic or hydrophilic entities by host-guest interaction and covalent bonding respectively. Dendrimer is the irresistible candidature for the formation of inclusion complexes capable of accomplishing the various applications. This is due to the presence of various terminal groups with varied functionalities. PAMAM Dendrimer has been growing interest because of their unique characteristics like globular, nanoscale, macromolecule with different functionalities at periphery. PAMAM is comparatively novel group of these distinctive materials that is grown from the core side and each half or complete generation needs some repeating reactions. Also it has potential applicability in a wide range of areas makes it the promising candidate for lots of applications.Herein, we have synthesized Polyamidoamine (PAMAM) dendrimer of various generations and characterized by Fourier transform infrared (FTIR) spectroscopy and Mass spectrometry. The -0.5G PAMAM has differential functionality and special characteristics which allows the formation of inclusion complexes with various molecules. At this place, the inclusion complexes formed with carbamide molecules, which implant more functionality through host-guest interaction compared to the host molecules
S.S. Hatkar; D.S. Bhatkhande; S. Khamparia; S.R. Satpute
Abstract
Water plays an important role in the body to perform various crucial functions which include mineral supply to the body. The relative contribution of water to the total dietary intake for selected trace elements and electrolytes lies between 1 and 20%. Minerals are inorganic supplements which are required ...
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Water plays an important role in the body to perform various crucial functions which include mineral supply to the body. The relative contribution of water to the total dietary intake for selected trace elements and electrolytes lies between 1 and 20%. Minerals are inorganic supplements which are required for humans in limited quantities in the range of 1 to 4000 mg per day, depending upon the type of mineral. Requirement of minerals changes from gender to different age group, similar to that of nutrients and other basic nourishment supplements. Calcium (Ca) is essential for humans in the development of bone and proper working of nerves and muscles. Magnesium (Mg), copper (Cu), zinc (Zn) and iron (Fe) are significant co-factors which are essential in various biochemical reactions. Iodine (I) is required for the synthesis of thyroid hormones which control body’s metabolism and many other body functions. Potassium (K) is significant for maintaining osmotic harmony among cells, and the interstitial liquid. Red platelets cannot work properly without iron in haemoglobin. Excessive consumption or insufficient intake of selected trace minerals can disturb the body balance and can cause various chronic effects. The paper studies the alterations in various biochemical functions when these trace minerals are consumed in disproportionate manner. This paper critically emphasizes on the controlled uptake of vital minerals such as Ca, Mg, Fe, Zn, Cu, I, K from water.
