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Dikshit A.K.,Indian Central Glass and Ceramic Research Institute
Polymer - Plastics Technology and Engineering | Year: 2012

The role of different organic polar solvents containing methylene group on rheological behaviour of coated polyimide precursor on silica optical fibre were investigated at different concentrations and temperatures with respect to corresponding original precursor itself. The influence of keto-methyl and N-methyl polar groups are in different chemical structure of organic solvents into the coated precursor against-solvent dilution process has been explored. The interaction in between functional groups moiety containing into precursor and polar methyl group of solvents was also analysed. A substantial knowledge of rheology into coating precursor of polyimide is an important issue to coat successfully into optical fibre. © 2012 Copyright Taylor and Francis Group, LLC.

Naskar M.K.,Indian Central Glass and Ceramic Research Institute
Journal of the American Ceramic Society | Year: 2010

Alumina nanoparticles were synthesized following hydrothermal process at 170°C for 6 h, using glucose and other water-based precursor materials. The uncalcined and calcined (550°-1200°C) particles were characterized by differential thermal analysis, thermogravimetry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and multipoint Brunauer-Emmett-Teller (BET) surface area. The microstructures of the calcined (at 550°C) particles were examined by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD and FTIR studies revealed that gamma-alumina (γ-Al2O3) persisted up to 1000°C followed by the appearance of alpha-alumina (α-Al2O3) at 1200°C. BET surface area analysis confirmed that the specific surface area of γ-Al2O3 was higher compared with α-Al2O3. Because of particle agglomeration, the crystallite sizes obtained by the BET method showed larger values than those determined by the XRD method for the samples calcined at 550°-1200°C. For 550°C-treated sample, FESEM micrograph showed the aggregated particles of size 20-80 nm, while TEM image of the same sample revealed a particle size of 5-10 nm. © 2010 The American Ceramic Society.

Dikshit A.K.,Indian Central Glass and Ceramic Research Institute
Optical Materials | Year: 2012

I present here the study of optical and fluorescence properties, structure and morphology of silica nanoparticles bearing laser dye molecules are electrostatically attached with high refractive index organic dopant in acrylic optical preform rod. The photo physical fluorescence behaviour of laser dye molecules at the surface of different size and shape of silica nanoparticles has been reported. The interaction of laser dye-nanoparticles, nature of particles, and effect of various sizes and shapes of silica nanoparticles on fluorescence properties has been investigated. The developed optical preform has high potential for possible applications as bio-analysis sensor probe. © 2012 Elsevier B.V. All rights reserved.

Saha J.,Indian Central Glass and Ceramic Research Institute | De G.,Indian Central Glass and Ceramic Research Institute
Chemical Communications | Year: 2013

Cubic (Im3m) mesoporous silica nanofibers were successfully prepared using a new F127-PVA-SiO2 tri-constituent assembly approach by the electrospinning technique. PVA was used to protect the F127 directed cubic micelles which usually deform during electrospinning. The preformed Au NPs can be loaded inside the mesopores of the nanofibers. © 2013 The Royal Society of Chemistry.

Maity T.,University College Cork | Goswami S.,Indian Central Glass and Ceramic Research Institute | Bhattacharya D.,Indian Central Glass and Ceramic Research Institute | Roy S.,University College Cork
Physical Review Letters | Year: 2013

We observe an enormous spontaneous exchange bias (∼300-600 Oe) - measured in an unmagnetized state following zero-field cooling - in a nanocomposite of BiFeO3 (∼94%)-Bi2Fe4O 9 (∼6%) over a temperature range 5-300 K. Depending on the path followed in tracing the hysteresis loop - positive (p) or negative (n) - as well as the maximum field applied, the exchange bias (HE) varies significantly with -HEp>HEn. The temperature dependence of HE is nonmonotonic. It increases, initially, till ∼150 K and then decreases as the blocking temperature TB is approached. All these rich features appear to be originating from the spontaneous symmetry breaking and consequent onset of unidirectional anisotropy driven by "superinteraction bias coupling" between the ferromagnetic core of Bi2Fe4O9 (of average size ∼19 nm) and the canted antiferromagnetic structure of BiFeO3 (of average size ∼112 nm) via superspin glass moments at the shell. © 2013 American Physical Society.

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