B. Sreenivasulu; S Venkatramana Reddy; P. Venkateswara Reddy
Abstract
Pure and (Mn, Ni) co-doped ZnS nano particles are synthesized by co-precipitation method using Poly Vinyl Pyrrolidone (PVP) as stabilizer. Powder XRD results exhibit cubic blended structure for all samples. The average crystallite sizes observed to be between around 2-3 nm. Uneven changes of crystal ...
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Pure and (Mn, Ni) co-doped ZnS nano particles are synthesized by co-precipitation method using Poly Vinyl Pyrrolidone (PVP) as stabilizer. Powder XRD results exhibit cubic blended structure for all samples. The average crystallite sizes observed to be between around 2-3 nm. Uneven changes of crystal structure of concerned nanoparticles are confirmed by the Transmission Electron Microscopy (TEM) studies. The crystalline sizes obtained from TEM (3-5 nm) agree well those of XRD data. The SEM micro graphs of (Mn, Ni) co-doped nanoparticles result in agglomeration with spherical shape. The EDAX Spectra reveal that in the chemical composition of the prepared samples, the co-doped elements are incorporated into ZnS lattice. Photoluminescence (PL) has been studied at 306 nm wavelength. Pure sample exhibits sharp peaks at 438 nm, 450 nm and 466 nm. The (Mn, Ni) co-doped powders exhibit slightly less intense peaks. The magnetic measurements reveal that the co-doped nanoparticles exhibit Room Temperature Ferromagnetism (RTFM). Copyright © 2018 VBRI Press.
Rohit R. Powar; Ashok B. Gadkari; Pravina B. Piste; Dnyandevo N. Zambare
Abstract
Nanoparticles of Zinc substituted Cobalt ferrite powders having general formula ZnxCo1-xFe2O4 (x = 0, 0.25, 0.5, 0.75, 1.0) have been produced by using analytical grade nitrates and hexadecyltrimethylammonium bromide (CTAB) as structure directing reagent via Chemical co-precipitation method. The structure ...
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Nanoparticles of Zinc substituted Cobalt ferrite powders having general formula ZnxCo1-xFe2O4 (x = 0, 0.25, 0.5, 0.75, 1.0) have been produced by using analytical grade nitrates and hexadecyltrimethylammonium bromide (CTAB) as structure directing reagent via Chemical co-precipitation method. The structure and morphology of prepared polycrystalline ferrite nanoparticles were investigated by X-ray diffraction (XRD), Fourier Transform Infrared Radiation (FTIR) and Scanning electron microscopy (SEM) respectively. Thermogravimetric differential analysis (TG/DTA) technique gives information about ferrite phase formation occurs beyond 450 ºC. The XRD analysis confirms the establishment of the cubic spinel structure with the presence of minor secondary phase of α-Fe2O3 (hematite) at a calcination temperature of 650 ºC. The polycrystalline mixed zinc cobalt ferrite nanoparticles showed a dual phase and crystallite size lies in the range 6-11 nm. FE-SEM microstructure shows the nearly spherical polycrystalline nanoparticles with a particle size in between 0.11-0.20 µm. The FT-IR spectra display two significant strong absorption bands nearby in the range of 400 cm-1 and 600 cm-1 on the tetrahedral and octahedral sites respectively. Copyright © 2018 VBRI Press.
Himanshu Bisaria; Pragya Shandilya
Abstract
Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. ...
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Ni-rich NiTi shape memory alloys (SMAs) are gaining more prominence compared to near equiatomic NiTi SMAs due to their excellent superelasticity and shape memory properties. The low density and high work output compared to steels make them an excellent choice for automotive and aerospace industries. The study explores the effect of machining parameters, namely, pulse off time, pulse on time, spark gap voltage, wire tension and wire feed rate on material removal rate (MRR), surface roughness (Ra), and surface morphology of Ni-rich NiTi SMA. The experimental results reveal that MRR & Ra increase with the increase in pulse on time while decrease with the increase in pulse off time and spark gap voltage. Wire feed rate and wire tension have negligible influence on MRR and SR. Surface defects, namely, recast layer, micro-cracks & voids were examined through scanning electron microscope (SEM). Energy dispersive X-ray (EDS) and X-ray diffraction (XRD) analysis results reveal the material transfer from wire electrode and the dielectric fluid on the machined surface. Copyright © 2018 VBRI Press.
K. Samuvel; K. Ramachandran; V. Ratchagar; G. Ravi
Abstract
Barium Titanate doped with Cobalt is known for both its electric and magnetic properties. The synthesis and characterization of Cobalt doped barium titanate; BaTi1-xCoxO3(BTCO) x = 0.5was investigated with a view to understand its structural, magnetic and electrical properties. A finest possible sample ...
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Barium Titanate doped with Cobalt is known for both its electric and magnetic properties. The synthesis and characterization of Cobalt doped barium titanate; BaTi1-xCoxO3(BTCO) x = 0.5was investigated with a view to understand its structural, magnetic and electrical properties. A finest possible sample of Co doped micro particles of BaTiO3 (BTO) with possible tetragonal structure via a solid-state route was prepared. Prepared samples of BaTi1-xCoxO3 (BTCO) were structural characterized by X-ray diffraction (XRD). The dielectric constant measurements of the samples were carried out at 1Hz to1 MHz Vibrating Sample Magnetometer (VSM) measurements revealed the magnetic nature of Cobalt doped BaTiO3. Ferroelectric hysteresis loop traced at the electric field in-between -15 to +15 (KV/cm). The relaxation phenomena that take place cane be attributable to the damping of dipole oscillator due to the application of external field. The impedance measurements were done up to 473 K in order to separate grain (bulk) and grain boundary contributions. The FESEM micrographs show proper grain growth and EDAX confirmed the presence of all the elements in samples. In the present study, various electrical properties of barium titanate based ceramics were explained and examples of the relevant applications were given. Copyright © 2017 VBRI Press.
Narendra Singh; Davinder Kaur
Abstract
Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray ...
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Ultrathin silicon carbide (SiC) films were grown on p type Si (100) substrate by RF magnetron sputtering at constant substrate temperature of 7000C for investigating thickness dependence of structural and photoluminescence properties. The structural and Photoluminescence properties were measured by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and photospectrometer respectively. X-ray diffraction pattern revealed (102) and dominant (105) reflections which corresponds to 4H-SiC and an enhancement in (105) peak intensity with increasing thickness was also observed. The thickness measured by X-ray reflectometry (XRR) reduces from ~ 46 nm to 12 nm by decreasing deposition time (40-10 minute) which in turn reduces the crystallite size. Photoluminescence spectra show a broad peak extending from ultraviolet to blue region centered at ~ 385 nm for film of thickness ~ 46 nm (deposition time 40 min). A shifting in Photoluminescence peak towards shorter wavelength (blue shift) with decreasing SiC ultrathin film thickness was observed, which could be attributed to quantum confinement effect. The improved Photoluminescence in ultrathin nanocrystalline SiC films could make it a potential candidate in optoelectronic and biomedical applications. Copyright © 2017 VBRI Press.
Sarika Singh; A.K. Shrivastava; Swati Tapdiya
Abstract
Cadmium Selenide (CdSe) doped with (Mn) Manganese Chloride grown, on commercial glass substrate usingChemical Bath Deposition Method. Growth time was kept at 1-2 hours. Magnese Chloride (Mncl2) was used for dopant. CdMnSe films so obtained were characterized using X-Ray Diffraction, Scanning Electron ...
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Cadmium Selenide (CdSe) doped with (Mn) Manganese Chloride grown, on commercial glass substrate usingChemical Bath Deposition Method. Growth time was kept at 1-2 hours. Magnese Chloride (Mncl2) was used for dopant. CdMnSe films so obtained were characterized using X-Ray Diffraction, Scanning Electron Microscopy, EdAX, andUV-Visible spectrophotometer and photoluminescence studies respectively. XRD study confirms that CdSe films are polycrystalline in nature and have cubic structure. The Debye-Scherer formula was used to calculate average particle size of pure and doped CdSe film. Thus, the particle size was decrease on doping. The effect of doping concentration Mn on the luminescence spectra of CdSe was studied. The emission spectra revealed that the intensity increased considerably in the presence of dopant ions. It is clearly observed from the surface morphological studies by SEM that the as-deposited CdSe and doped Mn concentration films are nanocrystalline, homogenous, without cracks or holes and well covered to the glass substrate. FE-SEM images show spherical particles having uniform distribution. Roughness of the films were totally eliminated. EDAX patterns confirms the presence of Cadmium, Selenide and Magnese chloride elements (2%, 5%)in sample. Optical band gap of pure CdSe film comes out to be 2.1 eV.After doping energy band gap was decreasing. Copyright © 2017 VBRI Press.
Nandeibam Nilima; Mamata Maisnam; Sumitra Phanjoubam
Abstract
Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction ...
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Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction studies showed diffraction peaks indicating single phase with spinel structure. However, peaks of SiO2 were found in composites of higher (x). The microstructure of the samples was studied by using Scanning Electron Microscopy. The crystallite size and average grain size were found to decrease with increase of SiO2 content. The room temperature frequency variation of dielectric constant and dielectric loss was measured from 100Hz-1MHz and they showed a dispersive behavior. The variation has been explained by Verwey mechanism of electron hopping and Koop’s two-layer model. The addition of SiO2 plays significant role in influencing the various structural, microstructural and electrical properties. Uniform and refined microstructures are observed with the addition of SiO2 and this reduces the value of dielectric constant and loss significantly, which is desirable for high frequency applications. The results obtained and mechanisms involved are discussed. Copyright © 2017 VBRI Press.
Sunita Khangembam; Maisnam Victory; Waikhom Surchandra; Sumitra Phanjoubam
Abstract
Recent technological breakthroughs and the desire for new functions generate an enormous demand for synthesizing new materials through different ways and methods which show superior properties compared with their pure counterparts. Presently, polycrystalline zinc doped nickel ferrites having the compositional ...
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Recent technological breakthroughs and the desire for new functions generate an enormous demand for synthesizing new materials through different ways and methods which show superior properties compared with their pure counterparts. Presently, polycrystalline zinc doped nickel ferrites having the compositional formula Ni1-xZnxFe2O4 where x = 0.0, 0.1, 0.2 and 0.4 were synthesized. Sol-gel auto combustion method was adopted for the preparation of these ferrites since it provides a simple and economic alternative technique ensuring good stoichiometric control, production of particles with narrow size distribution in a relatively shorter time, good homogeneity and high sinterability at lower temperature. Structural studies were carried out by XRD. Various structural properties like lattice parameter, crystallite size and density were calculated from the XRD data. Micro structural studies were carried out using Scanning Electron Microscopy (SEM), while the elemental compositions of all the samples were studied by Energy Dispersive X-ray Analysis (EDAX). The frequency variation of room temperature dielectric constant and dielectric loss was studied in the frequency range 100Hz – 1MHz and dispersive behavior was observed. The room temperature dc resistivity of all the samples was also investigated. Zn substituted nickel ferrites are found to be useful in microwave and electronic devices. Copyright © 2017 VBRI Press.
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.
Elangbam C. Devi; Ibetombi Soibam
Abstract
Manganese ferrite nanoparticles with chemical formula MnFe2O4 have been synthesized by low temperature chemical co-precipitation method. The structural and optical properties of the nanoparticles were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray ...
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Manganese ferrite nanoparticles with chemical formula MnFe2O4 have been synthesized by low temperature chemical co-precipitation method. The structural and optical properties of the nanoparticles were studied by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), fourier transform infra-red spectroscopy (FTIR) and UV-visible absorption spectroscopy. XRD confirm pure spinel phase formation of the prepared sample. All the observed peaks correspond to the standard diffraction pattern of manganese ferrite having JCPDS card number 74-2403. From the XRD data, the average crystallite size was calculated and found to be 27.40 nm. The FTIR spectrum shows the characteristic bands of the spinel ferrite. Morphology of the nanoferrites was given by SEM image revealing that the particles are approximately spherical in shape. The elemental composition along with their relative ratios was given by EDAX and was found to be in agreement with their initial calculated values. UV- visible absorption spectrum of the prepared sample shows characteristic absorption in visible range and from the UV-visible absorption data the band gap of the prepared sample was determined. MnFe2O4 nanoparticles were found to possess a narrow band gap of 1.4 eV which may find applications in photocatalytic degradation of pollutants. The simple co-precipitation method proves to be an effective method for synthesis of pure phase manganese ferrite nanoparticles. Copyright © 2017 VBRI Press.
Rajat K. Saha; Mrinal K. Debanath; Eeshankur Saikia; Vedant V. Borah; Kandarpa K. Saikia
Abstract
ZnO based nanoparticles find a wide range of applications starting from biosensors and drug-delivery systems to solar cells. Keeping an eye on the prospect for an application in the field of biotechnology, we analyze Cu-doped ZnO nanoparticles after the fabrication and necessary characterization of the ...
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ZnO based nanoparticles find a wide range of applications starting from biosensors and drug-delivery systems to solar cells. Keeping an eye on the prospect for an application in the field of biotechnology, we analyze Cu-doped ZnO nanoparticles after the fabrication and necessary characterization of the XRD data obtained, by using the tools of Nonlinear Dynamical Theory (NLD). One of the tools used called Lyapunov Exponent, bears the signature of the dynamical evolution of the particles as well as structure formation. This is calculated in order to quantify the underlying strange attractor present in the nanosystems, which happens to be the driving force behind the structure formation. The changes in the values of this parameter with the variation of the physical and chemical conditions, would pave the way for an efficient calibration for meaningful biological applications, which happens to be the focus of the present work. Differently sized ZnO nano particles are obtained by changing dopant percentage for inhibiting human pathogenic bacteria. Calibrations are made between the Zone of Inhibition (ZOI) and Lyapunov Exponent to obtain the required dopant percentage for a given ZOI vis-à-vis the same anti-bacterial effectiveness in terms of ZOI of a ZnO doped nano particle. Copyright © 2016 VBRI Press.
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
