ORCID Profile
0000-0002-4642-5990
Current Organisation
Bhabha Atomic Research Centre
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Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2DT12190E
Abstract: GdVO(4) : Ln(3+) (Ln(3+) = Dy(3+), Eu(3+), Sm(3+), Tm(3+)) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO(4) formation with increase of VO(4)(3-) present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO(4) to Ln(3+) and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared s les are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices.
Publisher: American Chemical Society (ACS)
Date: 19-05-2023
Publisher: American Scientific Publishers
Date: 02-05-2009
DOI: 10.1166/JNN.2009.026
Abstract: Eu3+ and Dy3+ doped YPO4 nanoparticles dispersible in methanol/water were prepared by the reaction of Y3+ and Eu3+/Dy3+ ions with ammonium dihydrogen phosphate in ethylene glycol medium at 160 degrees C. Nature and extent of strain associated with lattice has been found to change with incorporation of Eu3+/Dy3+ ion in the nanoparticles as well as the heat treatment temperature. Based on the TEM studies, it has been established that particles are highly crystalline with an average particle size of around 5 nm. Co-doping YPO4:Eu nanoparticles with Dy3+ ions followed by annealing them at high temperature (900 degrees C) lead to reduction in both Eu3+ and Dy3+ luminescence intensities from the s le and this has been attributed to the clustering effect of the lanthanide ions.
Publisher: American Scientific Publishers
Date: 11-2008
DOI: 10.1166/JNN.2008.246
Abstract: ZnGa 2 O 4 nanoparticles doped with lanthanide ions (Tb 3+ and Eu 3+ ) were prepared at a low temperature of 120 °C based on urea hydrolysis in ethylene glycol medium. X-ray diffraction studies have confirmed that strain associated with nanoparticles changes as Tb 3+ gets incorporated in the ZnGa 2 O 4 lattice. Based on steady state emission and excitation studies of ZnGa 2 O 4 :Tb nanoparticles, it has been inferred that ZnGa 2 O 4 host is characterized by a broad emission around 427 nm and there exists energy transfer between the host and Tb 3+ ions. Unlike this, for ZnGa 2 O 4 :Eu nanoparticles, very poor energy transfer between the host and Eu 3+ ions is observed. These nanoparticles when coated with ligands like oleic acid results in their improved dispersion in organic solvents like chloroform and dichloromethane.
Publisher: American Scientific Publishers
Date: 04-2009
Abstract: SnO2 nanocrystals in SiO2:Eu matrix have been prepared at a relatively low temperature of 170 degrees C for 4 h. Selective transition probability of Eu3+ emission could be done after a suitable excitation wavelength. The room temperature exciton formation at 285 nm for as-prepared nanoparticles is observed and this gives the Bohr's radius of 1.4 nm. Exciton formation disappears for the nanoparticles heated at 500 and 900 degrees C. This is related to the increase in particle size with heat-treatment. A wide-band-gap (4.35 eV) quantum dots is obtained and will be important in photonics and UV-lasing application.
No related grants have been discovered for Raghumani Ningthoujam.