Umaru Ahmadu; Abdulwaliyu B. Usman; Auwal M. Muhammad; Oyeleke I. Olarinoye; Moses Agida
Abstract
Co-doped barium calcium stannate titanate (Ba0.88Ca0.12Ti0.975Sn0.025O3) ceramics, synthesized via solid state reaction and sintered at 1100 °C/3 h. The ceramics were irradiated with thermal neutrons of up to 1.4 × 1010 n/cm2 using a5 Ci Am-Be source having an average flux of 2.7 × 104 ...
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Co-doped barium calcium stannate titanate (Ba0.88Ca0.12Ti0.975Sn0.025O3) ceramics, synthesized via solid state reaction and sintered at 1100 °C/3 h. The ceramics were irradiated with thermal neutrons of up to 1.4 × 1010 n/cm2 using a5 Ci Am-Be source having an average flux of 2.7 × 104 n/cm2.s. Structural analysis of the ceramics indicate a majorly polycrystalline material with a minor secondary phase. The 2θ positions were observed to shift slightly to higher angles and the microstrain remained constant with increase in fluence. The average crystallite size is ∼ 38 nm with anisotropy in lattice expansion observed. Rod-like grains, porous regions and agglomerations were observed in all the specimens. There was general increase in grain size with increase in fluence and the average grain size is∼1 μm. Chemical analysis indicates slight deviation from nominal ones for some irradiated samples. It is concluded that the structural and microstructural changes observed would not affect the performance of the devices based on this material when used in radiation environments of neutrons as the maximum fluence has not exceeded the order of magnitude of threshold for radiation damage. Copyright © 2017 VBRI Press.
Veena Choudapur; A. B. Raju; Arvind Bennal
Abstract
The studies on luminescent II-VI semiconducting nanomaterials have attracted widespread attention, due to their potential applications in optoelectronic and biophotonic devices. Amongst II-VI group semiconductor nanoparticles, ZnS Nano Particles with large exciton binding energy and wide direct bandgap ...
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The studies on luminescent II-VI semiconducting nanomaterials have attracted widespread attention, due to their potential applications in optoelectronic and biophotonic devices. Amongst II-VI group semiconductor nanoparticles, ZnS Nano Particles with large exciton binding energy and wide direct bandgap at room temperature have drawn considerable attention for exploring its interesting optoelectronic properties. In this paper, high band gap Zinc Sulphide nanocrystals are prepared by simple Co-precipitation method at different concentrations of precursors, and the role of sulphur concentration on structural and optical properties is studied. The Zinc Sulphide nanomaterial was prepared using low cost precursors and de ionised water as solvent without using any capping agents. As synthesized Zinc Sulphide nanocrystals were characterized by using X-ray diffraction (XRD), Energy Dispersive Spectroscopy analysis, UV-Visible Spectrophotometry, Photoluminescence, Scanning electron Microscopy (SEM) and Ellipsometry. X-ray diffraction studies revealed that as prepared of ZnS nanocrystals are Polycrystalline with Cubic phase with preferential orientation along (111) direction. The crystallite size of the order of 5-11nm were obtained. EDAX pattern confirms the presence of Zinc and Sulfur. From optical absorption measurements, it has been observed that the direct optical band gap energy increases from 4.4 to 5.2eV with decrease in sulphur concentration in ZnS and exhibit large quantum confinement effect. Ellipsometry was carried out to measure optical constants of ZnS thin film. The electrical conductivity of the film is measured for the film coated on ITO glass by two probe methods. Copyright © 2017 VBRI Press.
Udayraj C. Yadav; Yuvraj S. Malghe
Abstract
Nanosized barium cerate (BaCeO3) was prepared from barium cerium oxalate (BCO) precursor. Thermal decomposition of BCO precursor was studied using thermogravimetry(TG), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. BCO precursor ...
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Nanosized barium cerate (BaCeO3) was prepared from barium cerium oxalate (BCO) precursor. Thermal decomposition of BCO precursor was studied using thermogravimetry(TG), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. BCO precursor calcined at 1000°C for 2h gives nanosized BaCeO3 powder. Band gap of BaCeO3 was estimated using diffuse reflectance spectrophotometry and is found to be2.17 eV. Particle size distribution study reveals that particle size of BaCeO3varies between 10-70 nm. Dielectric behavior of BaCeO3 was studied with varying the temperature at different frequencies. BaCeO3 shows good dielectric and conductivity response. Copyright © 2017 VBRI Press.
Sweta Karmakar Ghosh; Vikram Thakur; Shubhajit Roy Chowdhury
Abstract
Magnetic Resonance Imaging is a non-invasive technique which basically consists of a main magnet, gradients, radio-frequency transmitter and receiver and scanner. Commercially available MR scanners are quite heavy. However this bio-device can be made low cost, low weight and also low magnetic field. ...
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Magnetic Resonance Imaging is a non-invasive technique which basically consists of a main magnet, gradients, radio-frequency transmitter and receiver and scanner. Commercially available MR scanners are quite heavy. However this bio-device can be made low cost, low weight and also low magnetic field. This work proposes the design and development of a low magnetic field MRI scanner of 0.2T magnetic field strength. This design is based on Helmholtz coil as the main magnet. The homogeneity observed within a radius of 15cm was about 2% in a coil of 30cm radius. While at the centre homogeneity was found much better. Strength of 75µT/m gradient magnetic field has been considered for the design. Maxwell coil has been used for longitudinal gradient and Saddle coil has been used for transverse gradient. The resonant frequency was obtained 8.516MHz for a main magnetic field of 0.2T for protons. Simulation results for magnetic flux density norm had been obtained for Helmholtz coil and Maxwell coil depicting the distribution of magnetic flux density. Also weight of the main magnet had been found to be quite less when compared with main magnet that are commercially used. Copyright © 2017 VBRI Press.
Aftab H. Mondal; Mohammad T. Siddiqui; Kehkashan Siddiqui; Qazi M. Rizwanul Haque
Abstract
In the present work, biosynthesis of silver nanoparticles (AgNPs) using isolate of Shigella sp. AS8 culture supernatant as a reducing agent has been demonstrated. Synthesis of AgNPs was completed within 180 min of incubation at 35 °C under bright light condition. The biosynthesized nanoparticles ...
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In the present work, biosynthesis of silver nanoparticles (AgNPs) using isolate of Shigella sp. AS8 culture supernatant as a reducing agent has been demonstrated. Synthesis of AgNPs was completed within 180 min of incubation at 35 °C under bright light condition. The biosynthesized nanoparticles were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray (EDX) and Atomic force microscopy (AFM). The formation of brown color reaction product with strong UV-vis spectrum absorption maxima at 411 nm due to surface plasmon resonance (SPR) indicated the synthesis of AgNPs. FTIR spectrum confirmed association of supernatant protein molecules with synthesized nanoparticles. DLS, TEM, FE-SEM and AFM showed biosynthesized nanoparticles were spherical in shape with an average size of 20 nm. EDX data analysis reveals presence of metallic silver. While, XRD analysis revealed that synthesized particles were pure and crystalline in nature. Further, AgNPs were evaluated as an antibacterial agent against extended spectrum β-lactamase (ESBL) positive water-borne pathogens. The results of present study suggest that biosynthesized AgNPs can be used to combat ESBL producing multidrug resistant bacteria.
P. Prabeesh; P. Saritha; I Packia Selvam; S. N. Potty
Abstract
Kesterite thin films have been fabricated by chemical spray pyrolysis technique using less toxic organic solvent followed by annealing at different temperatures in inert nitrogen atmosphere. Phase formation and structural evolution were studied by XRD and Raman spectroscopy. The films annealed at 450°C ...
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Kesterite thin films have been fabricated by chemical spray pyrolysis technique using less toxic organic solvent followed by annealing at different temperatures in inert nitrogen atmosphere. Phase formation and structural evolution were studied by XRD and Raman spectroscopy. The films annealed at 450°C and 500°C exhibited excellent properties required for photovoltaic absorber materials. UV-Vis spectroscopy was used to estimate absorption coefficient and band gap; the films annealed at 450°C and 500°C showed band gap of 1.65eV and 1.51eV, respectively. Surface morphological properties and film thickness were studied by FESEM and electrical properties by Hall measurement system. Films annealed at 500°C showed densely packed grains with thickness ~ 1.2μm. Electrical properties of the films annealed in nitrogen atmosphere were in good agreement with the values previously reported for CZTS thin films. Copyright © 2017 VBRI Press
Rachna .; Baljeet S. Saharan .; Mahender S. Yadav .; Nisha Sharma .
Abstract
A simple and efficient synthesis of silver nanoparticles (AgNPs) is reported here using red Dianthus caryophyllus flower, acting both as reducing and capping agent. The resultant silver colloids were characterized using UV-visible spectrophotometer, X-ray Diffractometer (XRD) and Transmission electron ...
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A simple and efficient synthesis of silver nanoparticles (AgNPs) is reported here using red Dianthus caryophyllus flower, acting both as reducing and capping agent. The resultant silver colloids were characterized using UV-visible spectrophotometer, X-ray Diffractometer (XRD) and Transmission electron microscope (TEM). The surface absorption plasmon response and kinematics of reduction of silver ions were observed by UV-visible spectroscopy. The crystalline fcc structure of AgNPs was confirmed by its XRD pattern. Their morphological study was done with TEM, showing spherically shaped AgNPs in the range 10-20 nm. The antibacterial action was also studied using Agar well diffusion method against pathogenic bacteria cultures (Staphylococcus aureus, Bacillus cereus and Escherichia coli). AgNPs showed better antimicrobial activity against S. aureus culture. Copyright © 2018 VBRI Press.
Gurpreet Kaur; Bikramjeet Singh; Paviter Singh; Manpreet Kaur; Anup Thakur; Manjeet Kumar; Rajni Bala; Akshay Kumar
Abstract
Nontoxic and earth abundant nanostructured semiconductors have experienced wide attention of researchers recently. One of the more studied material is Iron pyrite (FeS2) owing many different promising applications. Herein, the synthesis of nanostructures by varying the reactant precursors of iron and ...
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Nontoxic and earth abundant nanostructured semiconductors have experienced wide attention of researchers recently. One of the more studied material is Iron pyrite (FeS2) owing many different promising applications. Herein, the synthesis of nanostructures by varying the reactant precursors of iron and sulphur has been reported. The molar ratio of iron and sulphur precursors play a crucial role in determining the quality of nanostructures. This work further advances synthesis with pyrite purity, structure control and then promotes use in photovoltaics, photocatalysis and photoelectrochemistry applications. Copyright © 2017 VBRI Press.
. Baijnath; Pankaj Kumar Tiwari; Suddhasatwa Basu
Abstract
In the present work, different synthesis methods i.e., sol-gel method, glycine-nitrate method and solid state route have been used to synthesize lanthanum strontium cobaltite (LSCO), which is utilized as cathode in low and intermediate temperature solid oxide fuel cell (SOFC). Calcination temperature ...
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In the present work, different synthesis methods i.e., sol-gel method, glycine-nitrate method and solid state route have been used to synthesize lanthanum strontium cobaltite (LSCO), which is utilized as cathode in low and intermediate temperature solid oxide fuel cell (SOFC). Calcination temperature for LSCO has been determined by TGA. XRD, SEM, EDX and TEM have been used to assess the phase purity, crystallite size, morphology, distribution of constituent elements and particle size of synthesized LSCO material. Two-probe AC conductivity method has been used to calculate the ionic conductivity of LSCO in air environment between 400-800°C. LSCO synthesized by sol-gel method provided highest ionic conductivity of 0.42 S/cm at 700°C and lowest activation energy of 31.60 kJ/mol between 500 to 700 °C among all the methods. LSCO synthesized by sol-gel method gives lowest area specific resistance (ASR) of 3.52 Ω cm2 at 800°C for half-cell (LSCO/YDC). High ionic conductivity and low polarization resistance established LSCO synthesized by sol-gel method, as the potential cathode material. Copyright © 2018 VBRI Press.
Pradyumna Mogre; Sharanabasava V. Ganachari; Jayachandra S. Yaradoddi
Abstract
Polyaniline fibres were synthesized by chemical oxidative polymerization using different ratios of monomers in the feed in HCl medium. The synthesized polymers were characterized by employing Fourier transform infrared, UV-visible, X-ray diffraction techniques for understanding the details of the structure ...
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Polyaniline fibres were synthesized by chemical oxidative polymerization using different ratios of monomers in the feed in HCl medium. The synthesized polymers were characterized by employing Fourier transform infrared, UV-visible, X-ray diffraction techniques for understanding the details of the structure of the synthesized polymers. Morphological, thermal, and electrical conductivity of the as synthesized polymers were also studied by employing scanning electron microscopy, thermogravimetric analysis, and electrical conductivity, respectively. A three-step thermal degradation was observed for the polymer. It was observed that yield and intrinsic viscosity of polymer is not regularly dependant on monomer concentration in the feed. The polyaniline show better conductivity than Polythiophene. Copyright © 2018 VBRI Press.
Asheesh K. Sharma; Jayanth K. Swamy; Anjana Jain
Abstract
Piezoelectric polymer-ceramic composite materials are promising candidate for transducer application because of their inherent capability of combining the favourable properties of both ceramic and polymer materials. Present work discusses the dielectric properties of such composite films developed from ...
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Piezoelectric polymer-ceramic composite materials are promising candidate for transducer application because of their inherent capability of combining the favourable properties of both ceramic and polymer materials. Present work discusses the dielectric properties of such composite films developed from two piezoelectric materials viz. Poly(vinylidene fluoride) (PVDF) as a matrix and Lead Zirconate Titanate (PZT) as filler in PVDF. PVDF-PZT composite films were prepared by solvent casting method followed by hot pressing for better packing and connectivity of ceramic phase in the composite and hence improved piezoelectric properties in the material. The dielectric parameters of these films are evaluated by the measurement of dielectric constants (ε¢ and ε¢¢), intrinsic impedance, capacitance and dielectric loss, etc. as function of frequency at room temperature. The temperature dependence of the dielectric properties is studied as well from 40˚C to 75˚C. It was found that dielectric properties like permittivity and capacitance were quite stable in the frequency range 100 Hz-100 kHz. A variation of 20 to 50% in dielectric properties was observed, for increase in temperature with respect to room temperature, which may be accounted to pyroelectric behaviour of material.
Suresh Addepalli; Lakshmi Ganapathi Kolla; Uthanna Suda
Abstract
Aluminium titanate (Al2TiO5) thin films were deposited at room temperature by DC reactive magnetron sputtering. To make appropriate films for potential gate dielectric applications, we investigated the influence of annealing temperature on the structural, chemical and dielectric properties of Al2TiO5 ...
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Aluminium titanate (Al2TiO5) thin films were deposited at room temperature by DC reactive magnetron sputtering. To make appropriate films for potential gate dielectric applications, we investigated the influence of annealing temperature on the structural, chemical and dielectric properties of Al2TiO5 thin films. From XPS studies, in as-deposited films, it has been observed that the presence of Al3+ and Ti4+oxidation states which correspond to Al2O3 and TiO2 respectively. After annealing at 400 °C in oxygen ambient, the binding energies of Al 2p, Ti 2p and O 1s were shifted by ~ 1 eV towards lower binding energy. This indicates the formation of an intermediate compound of Al2O3 and TiO2. The extracted Al, Ti and O ratio was 2:1:5 and it confirms the formation of Al2TiO5. XRD studies indicate that the as-deposited films were amorphous in nature. After annealing at 400 °C, diffraction peak at 2θ = 50.6° along (200) plane corresponds to aluminum titanate (Al2TiO5) has been observed. Metal-Insulator-Semiconductor (MIS) capacitors were fabricated and characterized to estimate the dielectric properties of the deposited films. The as-deposited films show low dielectric constant (κ = 8.1) and high leakage current density (J = 2.4x10-2 A/cm2 at -1V) values. After annealing at 400 °C the films show improved dielectric constant (κ = 9.4) and leakage current density (J = 4.6x10-9 A/cm2 at -1V) values. The enhancement in the device properties can be attributed to the improved oxide and interface quality after annealing. Equivalent oxide thickness (EOT) of less than 1nm is required to use Al2TiO5 as an alternate gate dielectric to SiO2 in CMOS industry. To achieve this scaling of the dielectric thickness (<5 nm) is needed, which is under investigation. Copyright © 2017 VBRI Press.
Shuhaib Mushtaq; M.F Wani
Abstract
In the present study, micro hardness values of Iron-Copper based alloys with different compositions have been obtained by using Vickers indenter. The samples Fe-5Cu-1Sn-7.5BN (wt. %), Fe-5Cu-1.5Sn-5BN (wt. %) and Fe-5Cu-2.5Sn-2.5BN(wt. %) were prepared using Powder metallurgy technique. The elemental ...
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In the present study, micro hardness values of Iron-Copper based alloys with different compositions have been obtained by using Vickers indenter. The samples Fe-5Cu-1Sn-7.5BN (wt. %), Fe-5Cu-1.5Sn-5BN (wt. %) and Fe-5Cu-2.5Sn-2.5BN(wt. %) were prepared using Powder metallurgy technique. The elemental powder mixture was mixed for 2 hours, and compacted at a pressure of 500Mpa, and then was sintered in dry hydrogen atmosphere at a temperature of 9000C for 50 minutes time. Vickers hardness values were obtained under the loads of 0.01 kg to 0.3 kg. The material with 2.5 wt. % of Sn exhibited the highest value of the hardness. The material with higher hardness shows better mechanical and tribological properties and can be used for various applications such as gears, bearings, connecting rods cams etc. Copyright © 2017 VBRI Press.
Ketan Jagtap; Raju Pawade
Abstract
Biomanufacturing integrates life science and engineering fundamentals to produce biocompatible products improving the pre-eminence of living. Face turning is an important process used for producing the higher accuracy on metal implants especially on sliding parts. In this experiment effect of depth of ...
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Biomanufacturing integrates life science and engineering fundamentals to produce biocompatible products improving the pre-eminence of living. Face turning is an important process used for producing the higher accuracy on metal implants especially on sliding parts. In this experiment effect of depth of cut, feed rate and cutting speeds are considered on machined Co-Cr-Mo bio-implant alloy by application of RSM. The offline and online measured surface roughness (Ra) and cutting force (Fc) were considered respectively as response variables for investigations. The experimental result shows that depth of cut and feed rate are having predominating effect on measured surface roughness and cutting force respectively. Therefore, the developed models can be efficiently used to predict the surface roughness and cutting force on the machinability of Co-Cr-Mo alloy within 95% confidence intervals ranges of measured parameters. For checking the adequacy of model a confirmation test has been conducted. The optimized parameters can be useful for industrial developments in surface generation for bio-implants. Copyright © 2018 VBRI Press.
Neha Sharma; K. Prabakar; S. Ilango; S. Dash; A. K. Tyagi
Abstract
AIN thin films were grown by ion beam sputter deposition in reactive assistance of N+/N2+ ions on Si (100) substrates. During deposition, assisted ion energy (EA) was varied as 90 eV and 120 eV with a post deposition exposure to N2 plasma. The resultant films were characterized by grazing incidence x-ray ...
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AIN thin films were grown by ion beam sputter deposition in reactive assistance of N+/N2+ ions on Si (100) substrates. During deposition, assisted ion energy (EA) was varied as 90 eV and 120 eV with a post deposition exposure to N2 plasma. The resultant films were characterized by grazing incidence x-ray diffraction (GIXRD) for their structure and atomic force microscopy (AFM) for their root mean square (rms) surface roughness (δ). UV-VIS spectrophotometry was carried out to explore their optical band-gap with associated Urbach (EU) and weak absorption tail (EWAT) energies. Our results show that, AlN thin film grown with 90 eV reactive ion assistance possesses larger optical band gap (Eg) of 5.3 eV associated with comparatively narrower band tails when compared to those AlN thin film samples which were grown for 120 eV reactive ion assistance. These optical band-gaps are further correlated with corresponding Urbach energy tails which can be used as a measure of disorder in microstructure of the film. Also, appropriate optimization of energy tails substantiates the possibility of band gap engineering as per the requirement of different thin film devices. Copyright © 2017 VBRI Press.
Toshiyuki Sameshima; Yoshihiro Ogawa; Masahiko Hasumi
Abstract
Reduction of optical reflection loss at the intermediate region is discussed in three mechanical stacked samples: top Si and bottom Ge substrates, top GaAs and bottom Si substrates, and top GaP and bottom Si substrates using an epoxy-type adhesive with a reflective index of 1.47. Transparent conductive ...
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Reduction of optical reflection loss at the intermediate region is discussed in three mechanical stacked samples: top Si and bottom Ge substrates, top GaAs and bottom Si substrates, and top GaP and bottom Si substrates using an epoxy-type adhesive with a reflective index of 1.47. Transparent conductive Indium gallium zinc oxide (IGZO) layers with a refractive index of 1.85 were used as antireflection layers. IGZO layers were formed on the bottom surface of the top substrate and the top surface of the bottom substrate of the three stacked samples with thicknesses of 188, 130, and 102 nm. The IGZO layers well decreased the optical reflectivity of the stacked samples. The IGZO layers provided high effective optical absorbency Aeff of bottom substrates of 0.925, 0.943, and 0.931, respectively, for light wavelength regions for light in which the top substrates were transparent and the bottom substrates were opaque. High Aeff maintained for the light incident angle between 0 to 50o. Copyright © 2018 VBRI Press.
Bharat C. Dalui; Bikash Mandal; Debalina Das; Susanta Ghosh; I. Basumallick
Abstract
The electrochemical performances of electrochemically synthesized polyanilinenano (nPANI) material as cathode vs. zinc metal as anode is investigated.The nPANI particle is synthesized by galvanostatic electro-oxidation of aniline from interfacial solution on metal electrode surface and characterized ...
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The electrochemical performances of electrochemically synthesized polyanilinenano (nPANI) material as cathode vs. zinc metal as anode is investigated.The nPANI particle is synthesized by galvanostatic electro-oxidation of aniline from interfacial solution on metal electrode surface and characterized by UV-Visible, FTIR, powder XRD and TEM. The material is crystalline nano spheres with meso pores among them, uniformly distributed and dispersed. The sizes of the particles lie in 50-100 nm region. This nPANI is used as cathode material in Zn│(NH4)2SO4, ZnSO4(aq)│nPANI battery and its electrochemical performances is investigated by galvanostatic charge-discharge cycling. The electrochemical cell exhibits an open circuit potential of 1.3 volts and a discharge plateau with an average discharge potential of 1.1 volts. The maximum discharge capacity observed is 250 Ah.Kg-1.Copyright © 2017 VBRI Press.
S. Rajesh; K. Thyagarajan; Vasudeva Reddy Minnam Reddy
Abstract
Zinc Sulfide nanophosphor (ZnS) nanophosphor doped with 2 mol % Dysprosium (Dy) and co-doped with (2 – 6) mol % Manganese (Mn) was successfully prepared by cost-effective chemical co-precipitation method using polyvinylpyrrolidone (PVP) as the capping agent. The effects of dopant and co-dopant ...
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Zinc Sulfide nanophosphor (ZnS) nanophosphor doped with 2 mol % Dysprosium (Dy) and co-doped with (2 – 6) mol % Manganese (Mn) was successfully prepared by cost-effective chemical co-precipitation method using polyvinylpyrrolidone (PVP) as the capping agent. The effects of dopant and co-dopant concentrations on the various properties of ZnS were investigated by various characterizations like Powder X-ray Diffraction (PXRD) studies confirmed the cubic zinc blende structure of ZnS and no impurity peaks corresponding to Dy doping and Co-doped by Mn was observed. Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDAX) confirmed the presence of dopant Dy and co-dopants Mn in the prepared ZnS. Photoluminescence (PL) studies on Dy doped Mn and co-doped ZnS nanophosphor indicated that the emission wavelength 605 nm is tunable in the range of 400–650 nm with the incorporation of doped Dy and Co-doped Mn into ZnS host lattice with the excitation wavelength of 320 nm. Blue color of ZnS doped Dy by enhances to orange color due to co-doped with Mn ions. The chromaticity co-ordinates (CIE) and Correlated color temperature (CCT) of the phosphor were shows enhancement of blue to orange region; hence, it is useful for the fabrication of orange component of WLEDs and display applications. Copyright © 2018 VBRI Press.
Manpreet Kaur; Akshay Kumar; Manoj Sharma
Abstract
Composition regulation of semiconductors can engineer the band gap and thus tune the optical properties. For effective utilization of orange emitting phosphors in color conversion applications blue excitation is necessary. Here in this work, absorption and photoluminescence spectroscopic measurements ...
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Composition regulation of semiconductors can engineer the band gap and thus tune the optical properties. For effective utilization of orange emitting phosphors in color conversion applications blue excitation is necessary. Here in this work, absorption and photoluminescence spectroscopic measurements have been done to study the variation in band gap energy by changing the composition of ZnxCd1-xS nanocrystals. Further, ternary Mn doped ZnxCd1-xS semiconductor nanocrystals have been synthesized via an aqueous route over a wide composition range by adjusting the molar ratio of precursors which leads to tunable bandgap, thus propagate the progressive growth of light absorption and photoluminescence spectra. The variation in tunability of bandgap is due to the change in Cd/Zn ratio. By changing Cd/Zn ratio excitation wavelength shifts from UV to blue colour. 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.
Nagendra Vara Prasad M; Jeevan Kumar R; Munikrishna Reddy Y
Abstract
In the present work, Ag2O films are deposited at room temperature using DCMS (Magnetron Sputtering) method with the variation of pressure of O2 during the development of film. The pressure of O2 in the DCMS unit chamber is arranged between 2X10-2 and 6X10-2 Pa. Transmission and absorption spectrum are ...
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In the present work, Ag2O films are deposited at room temperature using DCMS (Magnetron Sputtering) method with the variation of pressure of O2 during the development of film. The pressure of O2 in the DCMS unit chamber is arranged between 2X10-2 and 6X10-2 Pa. Transmission and absorption spectrum are recorded to assess the impact of increasing thickness on certain optical parameters such as indirect band gap, direct band gap, dielectric constant etc. As O2 pressure is varies between 2X10-2 Pa and 6X10-2 Pa, optical energy band gap shows a decreasing trend between 1.041 eV and 0.942 eV. It is also observed that the absorption transmittance of the deposited films increases with the increase of thickness of the film. This way, the study reveals that all the parameters are affected by varying pressure of O2. The effective useful of theseO2-rich films is also discussed keeping in view the increasing importance of the modern technological applications such as photovoltaic cell fabrication. Thus, this technique can also be applied to produce films using other metal oxides. Copyright © 2017 VBRI Press.
Meena .; Annu Sharma; Sanjeev Aggarwal; Pawan K. Sharma
Abstract
Bio-degradable polymers such as starch, chitosan, cellulose etc which are extracted from renewable resources are attracting increasing interest in the recent years due to their environmentally friendly nature, low cost and high availability. In the present work, synthesis of colloidal silver nanoparticles ...
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Bio-degradable polymers such as starch, chitosan, cellulose etc which are extracted from renewable resources are attracting increasing interest in the recent years due to their environmentally friendly nature, low cost and high availability. In the present work, synthesis of colloidal silver nanoparticles and subsequently Ag-starch nanocomposite films were carried out via a green process. For synthesis of Ag nanoparticles water, soluble starch and fructose have been used as solvent, reducing agent and stabilizing agent respectively. The effect of varying concentration of colloidal Ag nanoparticles on the optical and structural properties of starch was investigated. The structural analysis of the nanocomposites was carried out using Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Size of the Ag nanoparticles from TEM micrograph comes out to be 10.75 ± 0.8 nm in the starch matrix. UV-visible absorption was further utilized to ascertain various optical constants like optical energy gap, Urbach’s energy, optical conductivity etc. The optical energy gap of starch decreases from 4.08 eV to 2.21 eV for Ag-starch nanocomposite film containing 0.50 wt% of Ag nanoparticles and the Urbach’s energy increases from 0.77 eV to 1.37 eV. Copyright © 2017 VBRI Press.
Brijesh Prasad; Bhingole P P
Abstract
Magnesium and its alloys have got great attention in recent times due to its potential to replace heaver alloys with equal strengths and lighter in weight, hence become potential materiel automobile, sports, aeronautical and biomaterials applications This study concentrates and summarizes ...
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Magnesium and its alloys have got great attention in recent times due to its potential to replace heaver alloys with equal strengths and lighter in weight, hence become potential materiel automobile, sports, aeronautical and biomaterials applications This study concentrates and summarizes the fundamental properties of magnesium and its alloys such as high strength, ductility non-corrosive behavior etc. Along with its developments in its physical metallurgy, forming process and strengthening mechanisms to enhance the mechanical strength followed by behavior of magnesium alloys under different working conditions and applications. A brief overview of the recent and systematic outline is reported for improvement of mechanical by strengthening mechanism along with its applications. This work would be very much helpful for the researchers to find the best strengthening method on looking on its various aspects of design, environment friendly behavior and optimum utilization of resources with saving the natural resources. Copyright © 2017 VBRI Press.
Ioannis Tsiaoussis; Nikos D. Charisiou; Maria A. Goula; Lazaros Tzounis; George Vourlias; oannis V. Yentekakis; Remi Chassagnon; Valerie Potin; Bruno Domenichini
Abstract
In the present work, we investigated the structural morphology of carbon species deposited on nickel catalysts supported on CeO2-ZrO2 (18.8 wt.% ceria), prepared by wet impregnation, during the dry reforming of methane (DRM) reaction by using Thermo-gravimetric Analysis (TGA), Raman Spectroscopy, ...
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In the present work, we investigated the structural morphology of carbon species deposited on nickel catalysts supported on CeO2-ZrO2 (18.8 wt.% ceria), prepared by wet impregnation, during the dry reforming of methane (DRM) reaction by using Thermo-gravimetric Analysis (TGA), Raman Spectroscopy, X-ray diffraction (XRD), High Resolution TransmissionElectron Microscopy (HRTEM) and Scanning Transmission Electron Microscopy- Energy dispersive spectroscopy(STEM-EDS). TGA results show that the amount of deposited carbon decreases upon increasing reaction temperature, which is consistent with the thermodynamics of the reactions responsible for carbon formation, and Raman analysis points to a simultaneous increase in its graphitization degree. XRD measurements reveal the existence of 2H-Graphite and TEM imaging mode as well as SAED patterns depict that in all temperatures under which the catalysts were tested (550, 650, 750 and 800 oC), the formation of multi wall carbon nanotubes (MWCNT). HRTEM observations also reveal that the Ni nanoparticles are often enclosed by the MWCNT. HRTEM images identify nanocrystalline areas with a tetragonal phase, P42/nmc(137), of Ce1-xZrxO2, and STEM-EDS analysis at the nanometer scale confirms a correlation between Ce and Zr in the average atomic ratio (% ), 1 to 5.19 - 6.94 respectively. The results presented herein confirm that biogas mixtures can be used as precursors for the production of MWCNTs. Copyright © 2017 VBRI Press
M. Malligavathy; D. Pathinettam Padiyan
Abstract
Phase pure bismite nanoparticles were successfully prepared by means of hydrothermal method by varying the precursor solution pH from 10 to 13. The as-prepared nanoparticles were characterized by different techniques such as X-ray diffraction pattern (XRD), Raman spectroscopy, Scanning electron microscopy ...
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Phase pure bismite nanoparticles were successfully prepared by means of hydrothermal method by varying the precursor solution pH from 10 to 13. The as-prepared nanoparticles were characterized by different techniques such as X-ray diffraction pattern (XRD), Raman spectroscopy, Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX). The effects of pH on the structural properties of these nanoparticles were corroborated using XRD and Raman spectrum. From the XRD pattern it is found that all the samples are polycrystalline in nature and the Raman spectra are used to confirm the phase transformation of the Bi2O3 nanoparticles. At the low pH value, the SEM image reveals that as-prepared samples are homogeneous with particle size of ~ 25 nm and with the increase in the pH value spherical particle forms uniform blocks like morphology for both the samples prepared at the pH 12 and 13. Copyright © 2017 VBRI Press.
