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531.
Partha HajraPradip Brahma Saurav DuttaSourish Banerjee Dipankar Chakravorty 《Journal of magnetism and magnetic materials》2012,324(7):1425-1430
Cr2O3 nanoparticles of sizes from 24 to 12 nm were synthesized by mechanical grinding. Magnetic hysteresis loops were observed in the temperature range 5-300 K. Zero-field magnetization measurements showed two peaks, at low temperature in the range 36-52 K and at high temperature in the range 255-290 K. They were found to shift to higher temperatures as the particle size was reduced. This was ascribed due to the enhancement of the effective anisotropy constant with a decrease in particle size. The exchange bias was found to increase as the particle size became smaller. This is believed to arise due to an increase in uncompensated spins as a result of large surface area created. 相似文献
532.
S.S. Kalyan Kamal P.K. Sahoo L. Durai P. Ghosal M. Manivel Raja S. Ram 《Journal of magnetism and magnetic materials》2012
Small crystallites of a metastable phase Co0.5Pt0.5 are precipitated by heating a rheological liquid precursor of cobalt–hydrazine complex and platinum chloride H2PtCl6·xH2O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co2+ and Pt4+ that recombine and grow as Co0.5Pt0.5. The PVP molecules cap a growing Co0.5Pt0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co0.5Pt0.5 phase (average crystallite size D∼8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ρ=14.09 g/cm3). A more ordered L10 phase (ρ=15.91 g/cm3) transforms (D≥25 nm) upon annealing the powder at temperature lesser than 700 °C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization Ms=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D≤31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L10 phase at 800 °C for 60 min, showing a surface modified coercivity Hc=7.781 kOe with remnant ratio Mr/Ms=0.5564, and Ms=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large Hc from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L10 phase. 相似文献
533.
Animesh Layek Somnath Middya Partha Pratim Ray 《Journal of Physics and Chemistry of Solids》2012,73(11):1358-1361
In our present study hydrogenated amorphous silicon (a-Si:H) thin films and solar cells have been prepared in a conventional single chamber rf-PECVD unit from silane–argon mixture by varying radio frequency (rf) power densities from 6 mW/cm2 to 50 mW/cm2. By optimizing the properties of the intrinsic material we have chosen a material which is deposited at 6 mW/cm2 rf power density, 0.2 Torr pressure, 175 oC substrate temperature and by 97% argon dilution. For this material minority carriers (holes) diffusion length (Ld) measured in the as deposited state is 180 nm and it degrades by 15% after light soaking. This high Ld value indicates that the material is of device quality. We have fabricated a single junction solar cell having the structure p-a-SiC:H/i-a-Si:H/n-a-Si:H without optimizing the doped layers. This set exhibits a mean open circuit voltage of 0.8 V and conversion efficiency of 7.7%. After light soaking conversion efficiency decreases by 15% which demonstrates that it is possible to deposit device grade material and solar cells from silane–argon mixture. 相似文献
534.
An “off-on” rhodamine-based fluorescence probe for the selective signaling of Cu(II) and Fe(III) has been designed and synthesized.
The optical properties of this compound have been investigated in acetonitrile-water (1:1) binary solution. Very interestingly,
this compound showed sensitivity and selectivity towards Cu(II) during absorption process and towards Fe(III) during emission
process. So this is a nice example of an excellent dual chemosensor for two biologically/physiologically very important transition metal ions using only the two very different techniques
(absorption and emission); both cases displayed only intensity enhancement. 相似文献
535.
Krishanu Ghosal 《Particle & Particle Systems Characterization》2023,40(1):2200154
In the current situation of the global coronavirus disease 2019 (COVID-19) pandemic, there is a worldwide demand for the protection of regular handling surfaces from viral transmission to restrict the spread of COVID-19 infection. To tackle this challenge, researchers and scientists are continuously working on novel antiviral nanocoatings to make various substrates capable of arresting the spread of such pathogens. These nanocoatings systems include metal/metal oxide nanoparticles, electrospun antiviral polymer nanofibers, antiviral polymer nanoparticles, graphene family nanomaterials, and etched nanostructures. The antiviral mechanism of these systems involves depletion of the spike glycoprotein that anchors to surfaces by the nanocoating and makes the spike glycoprotein and viral nucleotides inactive; however, the nature of the interaction between the spike proteins and virus depends on the type of nanostructure and a surface charge over the coating surface. In this article, the current scenario of COVID-19 and how it can be tackled using antiviral nanocoatings from the further transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with their different mode of action, are discussed. Additionally, it is also highlighted different types of nanocoatings developed for various substrates to encounter transmission of SARS-CoV-2, future research areas along with the current challenges related to it, and how these challenges can be resolved. 相似文献
536.
A variable temperature single crystal X-ray diffraction study of the ternary compound, Cu4TiTe4 is reported between 200–400 K. The temperature dependent study indicates the compound undergoes an order-disorder phase transition at ∼320 K. Below the transition temperature, the phase that crystallizes in the primitive cubic space group P 3 m with lattice parameter of a≈5.9 Å, transforms into the two-fold superstructure. It is modeled as a fourfold twinned rhombohedral structure. The transition is reversible. To relate the phases, a group-subgroup symmetry relations are established. Upon decreasing temperature, the atomic ordering is noticed in the occupationally disordered Cu-sites of Cu4TiTe4. This characteristic structural rearrangement may have a significant impact on the electronic structure of Cu4TiTe4. Hence, the detailed structural characterization is supposed to be useful for further understanding of thermoelectric transport properties in the Cu4TiTe4. 相似文献
537.
Amin Owais Sinha Subhojyoti Maji Partha Sona Mukherjee Rupam 《Journal of Solid State Electrochemistry》2023,27(9):2387-2394
Journal of Solid State Electrochemistry - We report the effect of indium doping on thermal stability and ionic conductivity of beta alumina NaInxAl11-xO17 solid electrolyte which is synthesized by... 相似文献
538.