Metal nanoparticles prepared by using plant extracts as reducing agents: A review

80-85The unusual properties of metal nanoparticles make them appropriate for utilization in various areas of optoelectronics, catalysis, pharmaceuticals, etc. They have been synthesized using numerous physical and chemical methods but currently the approach of green synthesis is catching worldwide attention due to being eco-friendlier and economic. In the present study we have prepared Silver (Ag), Iron (Fe), Palladium (Pd) and Zinc (Zn) nanoparticles via the leaves of plants (Melia azedarach, Urtica dioica and Ziziphus jujuba). The synthesized nanoparticles were characterized using UV-VIS spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Heat treatment was provided to the as synthesized Pd nanoparticles at different temperatures. The XRD pattern of Ag nanoparticles displayed formation of face-centered cubic (FCC) structure and those of Zn nanoparticles and as synthesized Pd nanoparticles showed low crystalline nature. Also, presence of oxides of metals along with the metals was found in the Fe, Zn samples, although Fe nanoparticles displayed crystalline behavior. Significant improvement in crystallinity on heating at 280 °C was shown by Pd nanoparticles, however, partial oxidation of the sample was also noticed in the XRD pattern. SEM images of as synthesized Ag, Fe, Pd and Zn nanoparticles revealed agglomeration, whereas SEM images of Pd nanoparticles heated at 280 °C displayed spherical particles clustered together

Online-growth measurements on the generation of metal nanoaerosol and their offline structural properties

93-98Aerosol, which is intentionally generated in the laboratory, is utilized to synthesize nanoparticles. As the size of suspended nanoparticles in nano regime, therefore, purposely generated aerosol is termed as nanoaerosol. The present study demonstrates the formation metal nanoparticles in gas-phase. For this purpose, the initial condition; is to create nanoaerosol that is, suspension of tiny metal particles in gas. By evaporating a metal source in the presence of gas, creates the condition of supersaturation and then by nucleation and condensation forms stable nuclei, which grow in size to form primary particles in gas. A high-temperature furnace is utilized to evaporate metal e.g. palladium with 10% silver (PdAg), in the high purity nitrogen, is known as a carrier gas. During the sparking process, growth of the PdAg nanoaerosol is monitored online by a scanning mobility particle sizer, as a function of different parameters. Size-distribution in produced nanoaerosol shifts towards larger mobility equivalent diameter value from 7.83 to 42.6 nm along-with the increase in number concentration, on increasing the evaporation temperature from 1200 to 1400 °C. To study the effect of sintering temperature on particle size, size-fractionation by a differential mobility analyzer and in-flight sintering of PdAg nanoaerosol have been carried out. On increasing the sintering temperature, the size of selected PdAg nanoparticles reduces. The geometric mean mobility equivalent diameters of fractionated PdAg nanoparticles of 17.9, 25.3 and 30.9 nm reduces to 15.2, 19.4 and 21.7 nm, respectively, due to the compaction. The value of geometric standard deviation is approximately 1.10, which reflects the monodisperse nature of PdAg nanoparticles in the generated nanoaerosol. An electrostatic precipitation technique is utilized to separate out PdAg nanoparticles from nanoaerosol onto suitable substrates. Formation of spherical and mono-crystalline PdAg nanoparticles is revealed by TEM studies

Radiosonde: A tool to monitor atmospheric profiles

103-106Monitoring with an instrument is important to enhance the knowledge of the atmosphere. An instrument consists of sensors and other important elements to measure and process the data of different kinds of meteorological parameters. Sensor is an essential part of the instrument because it records the information about the atmosphere and supplies the corresponding output in the data displayed for the users.This paper introduces the radiosonde observations to measure the vertical profiles of meteorological parameters (temperature, relative humidity, mixing ratio and wind speed) profilesover three stations i.e., Srinagar (J&K), Delhi, and Mumbai on 09 Aug 2018 (a monsoon day) and 15 Feb 2019 (a winter day) at 0000 GMT and 1200 GMT

Structural and opto-electronic features of pulsed laser ablation grown Cu2ZnSnS4 films for photovoltaic applications

We report synthesis of Cu2ZnSnS4 thin films of kesterite structure by sulfurization of pulsed laser deposited (PLD) CuZnSn composite films at optimized temperature. These films show sharp optical absorption edge in the range of 1.4-1.6 eV, when prepared under optimized conditions of deposition and sulfurization. In general, the processed films are found to be non-stoichiometric with deficiency of S and excess of Zn. Electrical conductivity measurements in the temperature range 50-300 K reveal hopping transport with activation energies <= 20 meV at T < 80 K and a room temperature resistivity varying from 0.1 to 2.7 Omega-cm