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71.
Mott-Hubbard anti-ferromagnetic insulator, NiO shows p-type semiconducting behaviour due to vacancy at Ni2+ site in its bunsenite structure. We report the modification of structural and magnetic order in NiO on Fe doping. NiO samples
at different Fe concentrations in the range 0 to 5 at.% have been prepared by chemical co-precipitation and post thermal decomposition
method. Both structural and magnetic characterization reveal that with increasing Fe doping concentration, NiO evolves as
a magnetically inhomogeneous state out of the parent homogeneous antiferromagnetic state. In addition, structural inhomogeneity
was also observed with Fe precipitating to γ-Fe2O3 phase, the signature of which could be clearly seen for Fe content beyond 2 at.%. At lower Fe content however, some amount
of Fe occupies lattice and interstitial sites in the NiO matrix and drive the latter to acquire ferromagnetic ordering, which
was evident from a clear hysteresis loop at 300 K.
相似文献
72.
Chandana Rath Sonal Singh P. Mallick D. Pandey N. P. Lalla N. C. Mishra 《Indian Journal of Physics》2009,83(4):415-421
Ferromagentic semiconductors have been actively pursued because of their potential as spin polarized carrier sources and easy
integration into semiconductor technology. One such material, ZnO has been shown to be a potential Diluted Magnetic Semiconductor
(DMS). The appearance of ferromagnetism, however, is found to be sensitive to the processing conditions. We report synthesis
of ZnO nanoparticles of size ∼20 nm by a simple co-precipitation technique using metal nitrates and NaOH as precipitant. The
particles are self-organised and reveal single crystalline behaviour in electron diffraction pattern. Incorporation of Co
in ZnO matrix leads not only to the reduction in crystallite size but also to the modification of the structure. At 5% Co,
the particles are highly textured. The particles also aggregate and the aggregated mass have nearly rectangular shape as seen
through TEM. Increasing Co to 10%, results into further reduction of particle size and the particles self organize in a line,
which looks like nanofibers. This alignment of particles increases by increasing the Co content further. This type of growth
of nanofibers above Co ≥ 10% is well correlated with the anisotropic peak broadening observed in the XRD spectra. In addition,
Co substitute Zn site up to 20% without showing any extra phase in XRD spectra as compared to 7 to 10% in case of bulk. Transport
and magnetic studies indicate that conductivity increases with increasing Co content, but carrier mediated ferromagnetism
is absent down to 10 K.
相似文献
73.
P. Mallick S. Majumder D.C. Agarwal D.K. Avasthi N.C. Mishra 《Applied Surface Science》2009,256(2):521-523
NiO nanoparticle thin films grown on Si substrates were irradiated by 107 MeV Ag8+ ions. The films were characterized by glancing angle X-ray diffraction and atomic force microscopy. Ag ion irradiation was found to influence the shape and size of the nanoparticles. The pristine NiO film consisted of uniform size (∼100 nm along major axis and ∼55 nm along minor axis) elliptical particles, which changed to also of uniform size (∼63 nm) circular shape particles on irradiation at a fluence of 3 × 1013 ions cm−2. Comparison of XRD line width analysis and AFM data revealed that the particles in the pristine films are single crystalline, which turn to polycrystalline on irradiation with 107 MeV Ag ions. 相似文献
74.
Direct methanol fuel cells (DMFCs) within all types of fuel cells are the most viable alternative to lithium-ion batteries in the portable application and recently attracted much attention. This study reviews on passive DMFC material development with emphasis on to the performance activity, cost, durability and stability aspect. This paper has reported the basic desirable characteristics of each component with their material development. This paper has reviewed all possible materials of passive DMFC component, which can make the passive DMFC compact and feasible energy source in the future. 相似文献
75.
P. Mallick Chandana Rath J. K. Dash R. Biswal D. C. Agarwal D. Behera D. K. Avasthi D. Kanjilal P. V. Satyam N. C. Mishra 《Indian Journal of Physics》2010,84(10):1399-1404
NiO thin films grown on Si(100) substrates by electron beam evaporation, were sintered at 500 °C and 700 °C. The films were
irradiated with 120 MeV Au9+ ions. Irradiation had different effects depending upon the initial microstructure of the films. Irradiation of the films
at a fluence of 3 × 1011 ions cm−2 leads to grain growth for the films sintered at 500 °C and grain fragmentation for the films sintered at 700 °C. At still
higher fluences of irradiation, grain size in 500 °C sintered film decreased, but the same improved in 700 °C sintered film.
Associated with the grain size, texturing of the films was also shown to undergo significant modifications under irradiation. 相似文献
76.
A facile synthesis route is described for the preparation of a poly-(o-aminophenol)-gold nanoparticle composite material by polymerization of o-aminophenol (AP) monomer using HAuCl4 as the oxidant. The synthesis was carried out in a methanol medium so that it could serve a dual solvent role, a solvent
for both the AP and the water solution of HAuCl4. It was found that oxidative polymerization of AP leads to the formation of poly-AP with a diameter of 50±10nm, while the
reduction of AuCl4
- results in the formation of gold nanoparticles (∼ 2nm). The gold nanoparticles were uniformly dispersed and highly stabilized
throughout the macromolecular chain that formed a uniform metal-polymer composite material. The resultant composite material
was characterized by means of different techniques, such as UV-vis, IR and Raman spectroscopy, which offered the information
about the chemical structure of polymer, whereas electron microscopy images provided information regarding the morphology
of the composite material and the distribution of the metal particles in the composite material. 相似文献
77.
We report here a novel in-situ synthetic method for the
preparation of poly (o-methoxyaniline) and palladium nanoparticle composite
material. Ortho-Methoxyaniline and palladium acetate were used as the precursors;
during the reaction o-methoxyaniline was oxidized and forms poly
(o-methoxyaniline) and palladium acetate is reduced forming palladium
nanoparticles. IR and Raman spectra provide information on the structure of
the polymer. The TEM and SEM analysis are used to determine the size of the
nanoparticles and the morphology of the polymer respectively. 相似文献
78.
The article represents an experimentally supported quantitative analysis to observe the effect of time, temperature, nanoclusters’ morphology, and instantaneous volume fractions on perikinetic heat conduction and Brownian motion-based induced convection mechanisms of oxide (Al2O3 and TiO2, size 25–30 nm) based nanofluids. The appropriate models of thermal conductivity have been introduced to study the effect of various parameters such as; varying volume fractions, suspensions’ stabilities, nanoclusters’ growth, temperature, and the liquid layering. The developed model could predict the thermal conductivity enhancements of nanofluids within the accuracy of ± 0.5% to ± 4.5.0% in the temperature range from 20°C to 50°C.
Abbreviations: DI: De-ionized water; DLS: Dynamic light scattering; XRD: X-rays diffraction; TEM: Transmission electronic microscope; SDBS:Sodium dodecyl benzene sulphonate.
Figure Effect of temperature on the Brownian Reynold number for Al2O3-H2O and TiO2-H2O nanofluids. 相似文献
79.
Gour Chandra Mandal Rahul Mukherjee Khaleda Mallick Paulomi Mandal Ardhendu Sekhar Patra 《中国光学快报(英文版)》2019,(6)
We have projected and verified a bidirectional intra-/inter-radio-access-technology carrier-aggregation method for a next-generation heterogeneous mobile network supported by filter bank multicarrier(FBMC). Successful transmission of intra/inter-band carrier aggregation between five broadband FBMC signals and three bands 4G long-term-evolution-advanced signal over 50 km single-mode fiber plus 10 m free-space is successfully broadcasted by employing an incoherent light-injection scheme in downlink. In uplink, two intra-bands carrier-aggregated wireless local area network Institute of Electrical and Electronics Engineers 802.11 g signal is carried over the equal distance. High receiver sensitivity, low error vector magnitude, and clear constellation diagrams show successful delivery of different wireless services for different consumers. Therefore, the proposed hybrid system should become a potential solution for a future mobile front-haul network because of its low latency and high capacity. 相似文献
80.
Feifei Liu Sudipta Mallick Timothy J. ODonnell Ruxianguli Rouzimaimaiti Yuheng Luo Rui Sun Marisa Wall Supakit Wongwiwatthananukit Abhijit Date Dane Kaohelani Silva Philip G. Williams Leng Chee Chang 《Molecules (Basel, Switzerland)》2022,27(10)
Seven new coumarinolignans, walthindicins A–F (1a, 1b, 2–5, 7), along with five known analogs (6, 8–11), were isolated from the roots of Waltheria indica. The structures of the new compounds are determined by detailed nuclear magnetic resonance (NMR), circular dichroism (CD) with extensive computational support, and mass spectroscopic data interpretation. Compounds were tested for their antioxidant activity in Human Cervical Cancer cells (HeLa cells). Compounds 1a and 6 showed higher reactive oxygen species (ROS) inhibitory activity at 20 μg/mL when compared with other natural compound-based antioxidants such as ascorbic acid. Considering the role of ROS in nuclear-factor kappa B (NF-κB) activation, compounds 1a and 6 were evaluated for NF-κB inhibitory activity and showed a concentration-dependent inhibition in Human Embryonic Kidney 293 cells (Luc-HEK-293). 相似文献