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71.
72.
M. Pal S.K. Pradhan P. Bose A. Datta D. Chakravorty 《Physica E: Low-dimensional Systems and Nanostructures》2006,31(2):224-227
Ni3Al alloys of nanometer dimensions in the range 10–38 nm could be synthesized by reaction sintering of sol–gel-derived Ni/SiO2 nanocomposite and commercially available micrometer-sized aluminum powder. The sintering was carried out at a temperature of 923 K and a pressure of 2.4 MPa. By a suitable choice of sintering conditions a disordered phase of Ni3Al was stabilized. The disordered phase could be converted to an ordered one by an increase of heat treatment temperature. 相似文献
73.
A method to study domain structure in ferroelectrics, using pyroelectric effect is described. Variation of pyroelectric signal
from the surface of a triglycine sulphate crystal plate has been studied by scanning the surface of the crystal with a low
wattage He-Ne laser beam. The integrated pyroelectric signal is due to two components, namely, (1) the primary component arising
out of the change in spontaneous polarization with temperature and (2) the delayed component arising out of the possible polarization
reversal. The component of an electric field along the ferroelectric axis due to thermal hemisphere within the crystal plate
formed by the laser beam has been calculated and shown to exceed coercive field, making polarization reversal possible. The
delayed pyroelectric signal is a measure of polarization reversal within the patch illuminated and its observed variation
over the surface yields information of the domain structure. 相似文献
74.
75.
Mandira Sinha H. Majumdar P. Basu Subinit Roy R. Bhattacharya M. Biswas M. K. Pradhan R. Palit I. Mazumdar S. Kailas 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):403-410
Fusion excitation functions are measured for the system 6Li + 28Si using the characteristic $ \gamma$ -ray method, encompassing both the sub-barrier and above-barrier regions, viz, E lab = 7-24 MeV. Two separate experiments were performed, one for the above-barrier region ( E lab = 11-24 MeV) and another for the below-barrier region ( E lab = 7-10 MeV). The results were compared with our previously measured fusion cross-section for the 7Li + 28Si system. We observed the enhancement of the fusion cross-section at sub-barrier regions for both 6Li and 7Li , but the yield was substantially larger for 6Li . However, for well-above-barrier regions, a similar type of suppression was identified for both the systems. 相似文献
76.
Shailaja J Kaanumalle LS Sivasubramanian K Natarajan A Ponchot KJ Pradhan A Ramamurthy V 《Organic & biomolecular chemistry》2006,4(8):1561-1571
Photochemistry of 17 aryl alkyl ketones included within cation exchanged zeolites has been examined. In solution five of the 17 ketones undergo intramolecular hydrogen abstraction reaction even in the presence of a chiral amine and the rest are photoreduced to the corresponding alcohol. Within zeolites all 17 ketones yielded in presence of a chiral amine, the corresponding alcohol as the major product. When a chiral amine was used as the coadsorbent within alkali ion exchanged zeolites, enantiomerically enriched alcohol was formed in all cases. The best chiral induction was obtained with phenyl cyclohexyl ketone (enantiomeric excess: 68%). 1H-13C Cross Polarization Magic Angle Spinning (CP-MAS) experiments, with a model ketone (perdeuterated acetophenone) and chiral amine (pseudoephedrine) included within MY zeolites, suggested that the cation brings the reactant and the chiral amine closer. The role of the cation in such a process is also revealed by the computation results. The results presented here highlight the importance of a supramolecular structure in forcing a closer interaction between a reactant and a chiral inductor that could be used to achieve asymmetric induction in photoproducts. 相似文献
77.
78.
Biswajit Ghosh 《Applied Surface Science》2010,256(13):4328-3372
In this work SnS thin films were electrochemically deposited on ITO coated glass substrate by galvanostatic electrodeposition at different pH of the plating bath. The working electrode used in these studies was low cost high purity graphite rod. The as-deposited films were found to be smooth, pinhole free and well adherent to the substrate with no powdery deposition. EDX measurements revealed that all the SnS films were non-stoichiometric in nature with variation from Sn-excess to S-excess compositions. XRD pattern showed that all the SnS thin films had orthorhombic polycrystalline structure. The direct bandgaps of all the films were found to be in the range 1.54-1.58 eV. ITO/SnS/In structure exhibited linear current-voltage characteristics, establishing the ohmic nature of both ITO/SnS and SnS/In junctions. Furthermore, SnS layer was grown on CdS film using electrodeposition technique. The heterostructure ITO/CdS/SnS/In was characterized under dark and illuminated conditions. From forward biased I-V characteristics several junction parameters like barrier height, diode ideality factor and series resistance of the heterostructure were extracted using Cheung model. 相似文献
79.
Cd1−xZnxTe is a key material for fabrication of high-energy radiation detectors and optical devices. Conventionally it is fabricated using single crystal growth techniques. The method adopted here is the deposition of elemental multilayer followed by thermal annealing in vacuum. The multilayer structure was annealed at different temperatures using one to five repetitions of Cd-Zn-Te sequence. X-ray diffraction pattern for the multilayer with five repetitions revealed that annealing at 475 °C yielded single-phase material compared to other annealing conditions. EDX spectroscopy was carried out to study the corresponding compositions. Photoluminescence properties and change of resistance of the multilayer under illumination were also studied. The resistivity of the best sample was found to be a few hundreds of Ω cm. 相似文献
80.
Pabitra Kumar Pradhan Manoj Kumar Pandey 《Mathematical Methods in the Applied Sciences》2020,43(9):6081-6092
The system of generalized Chaplygin gas equations with a coulomblike friction term has been investigated by using the famous Lie symmetry method. A direct and systematic algorithm based on the adjoint transformation and invariants of the admitted Lie algebras is then used to construct one- and two-dimensional optimal system of the Chaplygin gas equations. Inequivalent classes of group invariant solutions are then obtained using the one-dimensional optimal system. Further, the evolutionary behaviour of the weak discontinuity wave within the state characterized by one of the group invariant solutions is investigated in detail, and certain observations are noted in respect to their contrasting behaviour. 相似文献