s. Suresh; v. Seetharaman; R. Mohan Kumar
Abstract
p-Toludinium fumarate (PTF) a potential organic single crystal was grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study was used to compute the unit cell parameters. The nuclear magnetic resonance spectral study reveals the proton and carbon molecular structure ...
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p-Toludinium fumarate (PTF) a potential organic single crystal was grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study was used to compute the unit cell parameters. The nuclear magnetic resonance spectral study reveals the proton and carbon molecular structure of PTF crystal. Optical band gap and the percentage of optical transmission were established by using UV-visible spectroscopy. Photoluminescence studies show that emission is independent of excitation wavelength. Dielectric constant (ε') and dielectric loss (tan δ) of PTF crystal were studied. The third order nonlinear refractive index (n2) and third order nonlinear absorption coefficient (β) were estimated by Z-scan technique.
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.
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.
Shobhna Choudhary; Ram J. Sengwa
Abstract
The dielectric and electrical spectra of solution cast prepared nanocomposite films comprising poly(vinyl alcohol) (PVA) as polymer matrix and zinc oxide (ZnO) as inorganic nanofiller (PVA–x wt% ZnO (x = 0, 1, 3 and 5)) have been investigated in the frequency range from 20 Hz to 1 MHz. Anomalous ...
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The dielectric and electrical spectra of solution cast prepared nanocomposite films comprising poly(vinyl alcohol) (PVA) as polymer matrix and zinc oxide (ZnO) as inorganic nanofiller (PVA–x wt% ZnO (x = 0, 1, 3 and 5)) have been investigated in the frequency range from 20 Hz to 1 MHz. Anomalous increase is observed in real part of complex permittivity with increase of ZnO concentration, whereas relaxation peak corresponding to PVA chain segmental motion is appeared in the intermediate frequency region of dielectric loss tangent and the loss part of electric modulus spectra of the nanocomposites. These results confirm that the interaction of ZnO nanoparticles with hydroxyl groups of PVA acts as exciter for polymer chain segmental dynamics in the nanocomposites. The temperature dependent dielectric investigations on PVA–3 wt% ZnO film reveal that the dielectric polarization and chain segmental dynamics increase with the increase of temperature. The dielectric relaxation and conductivity activation energies values of the film are determined from the Arrhenius relation, which are found equal. The X-ray diffraction study confirms that the crystalline phase of PVA matrix abruptly reduces with doping of only 1 wt% ZnO which suggests that the interaction of polymer-nanoparticles significantly alter the hydrogen bonded crystalline structure of pristine PVA matrix. The dielectric and electrical results showed that these nanodielectrics are potentially useful as an electrical insulation material for various electronic devices. Copyright © 2017 VBRI Press.
Ram J. Sengwa; Shobhna Choudhary
Abstract
Dielectric dispersion and relaxation behaviour of aqueous solution grown polymeric nanocomposite films consisting of poly(vinyl alcohol) (PVA) and alumina (Al2O3) (PVA–x wt% Al2O3 (x = 0, 1, 3 and 5)) have been studied in the frequency range from 20 Hz to 1 MHz by employing dielectric relaxation ...
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Dielectric dispersion and relaxation behaviour of aqueous solution grown polymeric nanocomposite films consisting of poly(vinyl alcohol) (PVA) and alumina (Al2O3) (PVA–x wt% Al2O3 (x = 0, 1, 3 and 5)) have been studied in the frequency range from 20 Hz to 1 MHz by employing dielectric relaxation spectroscopy (DRS). It is found that at constant frequency, the real part of complex permittivity increases nonlinearly with the increase of Al2O3 nanoparticles concentrations in the PVA matrix, whereas it decreases with increase of frequency at constant concentration of Al2O3. The temperature dependent investigation on PVA–3 wt% Al2O3 film reveals that the dielectric properties increase with the increase of temperature confirming its thermally activated dielectric behaviour. The ac electrical conductivity of the nanocomposites increases and the impedance values decreases with the increase of frequency which are moderately affected by Al2O3 concentrations(x = 0 to 5 wt%) and temperatures (30 to 60 °C). The dc conductivity and relaxation time of PVA chain segmental motion of the nanocomposites obey the Arrhenius behaviour. The X-ray diffraction (XRD) study reveals that the crystallite size and amorphous phase of PVA increase with the increase of Al2O3 concentration in the PVA–Al2O3 nanocomposites. Results of this study confirm the suitability of PVA–Al2O3 nanocomposite materials as tunable nanodielectric for their use as insulator and substrate in the fabrication of microelectronic devices operated at audio and radio frequencies. Copyright © 2017 VBRI Press.
Panchatcharam Damodaran; Mani Mahadevan; Pandurangan Anandan; Palanivelu Shanmugha Sundaram; Rajamanickam Rajasekaran
Abstract
Glycine has the simplest structure among all amino acids. Many attempts have been made to grow different derivative crystals of glycine. However, the title compound was not investigated thoroughly to understand the usability of the crystal for its device application. In the present investigation, using ...
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Glycine has the simplest structure among all amino acids. Many attempts have been made to grow different derivative crystals of glycine. However, the title compound was not investigated thoroughly to understand the usability of the crystal for its device application. In the present investigation, using slow evaporation solution growth technique, single crystals of glycine have been grown in the presence of potassium iodide. Detailed investigations were made on structural and thermal properties of the grown crystals. Structural analysis was carried out by X-ray diffraction method, Fourier Transform Infrared, FT-Raman and Nuclear Magnetic Resonance spectral methods to conform the grown crystals. Thermal stability of the grown crystals was studied by Thermogravimetric (TG) and Differential Thermal analysis (DTA) and it was found that the crystal is stable up to 113°C. UV-Vis spectral analysis has been carried out and the crystal has not any significant absorbance in the entire visible region. Dielectric studies for the grown samples have also been studied. Nonlinear optical property has been confirmed by Kurtz powder technique and found that the grown crystal has nearly fifty percentage of SHG efficiency as that of standard KDP sample. The observed properties have confirmed that the grown crystal is suitable for nonlinear optical applications. Copyright © 2017 VBRI Press.
Trilok K. Pathak; L. P. Purohit
Abstract
ZnO and ZnO:N thin films were deposited on plane glass substrate using RF sputtering method. The crystalline structure and surface morphology of the film was investigated using XRD and SEM. The XRD patterns of ZnO thin films have largest crystalline orientation for the (002) peak and shows wurtzite structure. ...
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ZnO and ZnO:N thin films were deposited on plane glass substrate using RF sputtering method. The crystalline structure and surface morphology of the film was investigated using XRD and SEM. The XRD patterns of ZnO thin films have largest crystalline orientation for the (002) peak and shows wurtzite structure. The ZnO thin films composed of dance packing, grains without any cracks indicating uniform grain size distribution. The transmittance and absorbance of ZnO thin film was measured using UV-VIS-IR spectrophotometer in the wavelength range 200 nm-800 nm. The band gap of ZnO film was3.26 eV calculated by Tauc’s plot method. Photoluminescence property was also investigated at the excitation wavelength 325 nm. A.C. conductivity measurements carried out on the ZnO/ZnO:N thin films at room temperature in the frequency range 10 KHz to 0. 1MHz. This measurement also helps to distinguish between localized and free band conduction.The study demonstrated that ZnO and ZnO:N thin films fabricated by RF sputtering method can be used in electronicand optoelectronic applications due to high transmittance in visible region, large bandgap and localized conduction. Copyright © 2016 VBRI Press.
Kirandeep Singh; Shuvam Pawar; Davinder Kaur
Abstract
Silicon integrated vertically aligned Ni-Mn-In nanorod arrays having ~100 nm length were investigated for shape memory behavior and magnetocaloric effect. The room temperature X-ray diffraction (XRD) patterns revealed the (220) oriented pure austenitic cubic phase growth of Ni–Mn–In nanorods. ...
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Silicon integrated vertically aligned Ni-Mn-In nanorod arrays having ~100 nm length were investigated for shape memory behavior and magnetocaloric effect. The room temperature X-ray diffraction (XRD) patterns revealed the (220) oriented pure austenitic cubic phase growth of Ni–Mn–In nanorods. The systematic thermo-magnetic (M-T) plots, resistance vs. temperature (R-T) measurements, as well as the negative slope of Arrott plots (H/M vs. M2) curves revealed the existence of significant shape memory effect in 100 nm Ni-Mn-In rods between 230 ≤ T≤ 294 K region. The formation of narrow hysteresis between field cooled (FC) and field warm (FW) curves in contrast to previous studies which reported broadness in the martensitic transformation temperature regime with decreasing thickness [1], can be ascribed to reduced substrate clamping effect due to vertically aligned growth of Ni-Mn-In. The magnetocaloric curves evaluated from M-H study indicates that large magnetic field magnitude dependent entropy change occurs in Ni-Mn-In rods, a maximum attainable ΔSM ~ 0.4 mJ/cc.K was observed at 275 K. Such vertically aligned growth of Ferromagnetic Shape Memory Alloys (FSMA’s) thin films over semiconductor substrate exhibiting significant shape memory behavior could prove useful in many MEMS/NEMS applications as well as opens possibility of futuristic self-cooled spintronics devices like magneto-electric random access memory (ME-RAM). Copyright © 2016 VBRI Press.
Shahadat Hussain; Ashish K. Jain; Md. A. Ansari; Abhishek Pandey; Rupa Dasgupta
Abstract
Copper based shape memory alloys are studied throughout the world for their high transition temperatures and high thermal stability. Among Copper based shape memory alloys(SMAs), Cu-Al-Mn SMAs have shown good ductility and high transition temperature. Only those alloy systems that can show the formation ...
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Copper based shape memory alloys are studied throughout the world for their high transition temperatures and high thermal stability. Among Copper based shape memory alloys(SMAs), Cu-Al-Mn SMAs have shown good ductility and high transition temperature. Only those alloy systems that can show the formation of β phase are capable to demonstrate the shape memory properties. In this paper the effects of the alloying elements on the formation of martensite phase have been studied exclusively. Addition of 1 wt% of Fe, Cr and Ti to the Cu-12.5Al-5Mn shape memory alloy has been investigated in detail. Therefore, four alloys have been synthesized through liquid metallurgy route using pure metals of 99.9% purity in a melting furnace weighing 1kg each. Samples were heat treated at the temperature of 920˚C for 2 hours and then quenched in ice water. The optical micrographs show the formation of the martensite structures in all the samples except in the samples in which 1 wt% Fe was added. X-Ray diffractions also revealed the same facts as obtained in the optical microscopy. Vickers Hardness of all four samples were carried out. The result shows no sign of martensite formation in sample containing Fe; therefore, this alloy should not be used for further study in the direction of understanding shape memory behaviors of the copper based shape memory alloys. Moreover, it was also observed that the addition of Cr yielded good martensitic formation as compared to the alloy containing Ti. Copyright © 2016 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.
