NOPR Collection:

Comparative study of physicochemical properties of CoFe2O4/MWCNT nanocomposites

2019-08-02T10:00:06Z

Title: Comparative study of physicochemical properties of CoFe2O4/MWCNT nanocomposites Authors: Khan, Meenu; Pawar, Hariom; Kumari, Manisha; Rathore, Deepshikha; Dwivedi, UK Abstract: CoFe₂O_4/MWCNT (CFO/MWCNT) nanocomposites have been synthesized using Co-precipitation and solid state method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and impedance spectroscopy have been used to determine structural, morphological and dielectric properties of synthesized nanocomposites. The particle size was found to be 3 nm, 3.3 nm and 4 nm for CFO, C-CFO/MWCNT and G-CFO/MWCNT, respectively, using Scherrer formula. Aggregation of nanoparticles has been acquired by SEM analysis. From impedance spectroscopy, it has been observed that the dielectric constant decreases with increase in frequency and dielectric constant and loss both are more for C-CFO/MWCNT nanocomposites than that are for G-CFO/MWCNT nanocomposites. Page(s): 93-95

Hydrogen induced resistance and optical transmittance of pulsed laser deposited Pd/Mg thin films

2019-08-02T09:57:45Z

Title: Hydrogen induced resistance and optical transmittance of pulsed laser deposited Pd/Mg thin films Authors: Gautam, Yogendra K; Kumar, Ashwani; Ambedkar, Anit K; Kumar, Vipin; Singh, Beer Pal Abstract: The hydrogen detection is an important issue for the societal acceptance of H₂ as energy carrier. In present research work, we have investigated hydrogen sensing and optical properties of Pd/Mg thin films on glass substrate deposited by pulsed laser (PL). As-deposited thin films have been exposed (hydrogenation) to H₂ gas (2 bar) at room temperature in a hydrogenation unit. Hydrogenated and dehydrogenated (at different temperatures) samples have been characterized using X-ray diffractometer (XRD), field-emission scanning electron microscopy (FE-SEM), UV-Vis-NIR spectrophotometer, atomic force microscopy (AFM). XRD results confirm the formation of hydride (MgH₂) tetragonal phase upon hydrogenation of Pd/Mg films. Hydrogen induced resistance response of Pd/Mg films has been measured in-situ during hydrogenation/dehydrogenation process by using two- probe electrical method. The response time (sensitivity) of Pd/Mg films for hydrogen gas is ~ 60 s at room temperature. The study of optical transmittance of hydrogenated Pd/Mg films indicates their switchable mirror behavior. Page(s): 96-100

Template free synthesis of PbS nanoparticles by sol-gel facile method under IR radiation at room temperature

2019-08-02T09:54:38Z

Title: Template free synthesis of PbS nanoparticles by sol-gel facile method under IR radiation at room temperature Authors: Ravikant; Gaur, Jyotshana; Sharma, Sanjeev K; Singh, Beer Pal Abstract: Lead sulfide (PbS) nanoparticles have been synthesized from the precursor of lead nitrite tetrahydrate [Pb(NO₃)₂.4H₂O] and thiourea [CH₄N₂S] at room temperature by sol-gel method under the infrared (IR) irradiation. The synthesized PbS nanoparticles have been characterized by XRD, FE-SEM, UV-vis spectrophotometer, and FTIR. The dominant peak (200) in XRD pattern, microstructure and the absorption of PbS have been confirmed the formation of nanoparticles. The crystallite size of PbS nanoparticle has been observed to be 13 nm. The lattice constant “𝑎” of as-synthesized nanostructured PbS powder has been estimated to be 5.99 Å closed to the standard one 5.93 Å. The strain has been determined from W-H Plot and estimated to be 1.75×10^-3. Page(s): 101-105

Dielectric relaxation of 1-nitropropane-ethanol mixtures using pico second time domain technique from 10 MHz to 50 GHz

2019-08-02T09:52:19Z

Title: Dielectric relaxation of 1-nitropropane-ethanol mixtures using pico second time domain technique from 10 MHz to 50 GHz Authors: Shinde, R V; Deshmukh, A R; Kumbharkhane, A C Abstract: Complex dielectric measurements in the frequency range 10 MHz - 50 GHz have been carried out in 1-nitropropane-ethanol mixtures with various concentrations by using a time domain reflectometry (TDR) at 283 K to 298 K. The dielectric relaxation response of 1-nitropropane-ethanol mixtures have been analyzed by using Debye model. The dielectric parameters such as static dielectric constant, relaxation time, excess permittivity, excess inverse relaxation time, Kirkwood correlation factor, enthalpy of activation and Gibbs free energy of activation have been determined for 1-nitropropane-ethanol system. The study confirms that the intermolecular interaction varies significantly with the increase in concentration of 1-nitropropane in ethanol. Page(s): 106-111