title: Synthesis characterization and luminescence studies of gamma irradiated nanocrystalline yttrium oxide.
abstract: Nanocrystalline Y2O3 is synthesized by solution combustion technique using urea and glycine as fuels. X-ray diffraction (XRD) pattern of as prepared sample shows amorphous nature while annealed samples show cubic nature. The average crystallite size is calculated using Scherrer's formula and is found to be in the range 14-30 nm for samples synthesized using urea and 15-20 nm for samples synthesized using glycine respectively. Field emission scanning electron microscopy (FE-SEM) image of 1173 K annealed Y2O3 samples show well separated spherical shape particles and the average particle size is found to be in the range 28-35 nm. Fourier transformed infrared (FTIR) and Raman spectroscopy reveals a stretching of Y-O bond. Electron spin resonance (ESR) shows V(-) center, O2(-) and Y(2+) defects. A broad photoluminescence (PL) emission with peak at ~386nm is observed when the sample is excited with 252 nm. Thermoluminescence (TL) properties of γ-irradiated Y2O3 nanopowder are studied at a heating rate of 5 K s(-1). The samples prepared by using urea show a prominent and well resolved peak at ~383 K and a weak one at ~570 K. It is also found that TL glow peak intensity (I(m1)) at ~383 K increases with increase in γ-dose up to ~6.0 kGy and then decreases with increase in dose. However, glycine used Y2O3 shows a prominent TL glow with peaks at 396 K and 590 K. Among the fuels, urea used Y2O3 shows simple and well resolved TL glows. This might be due to fuel and hence particle size effect. The kinetic parameters are calculated by Chen's glow curve peak shape method and results are discussed in detail.
authors.affiliation: Department of Physics, Jnanabharathi Campus, Bangalore University, Bangalore 560 056, India.
authors.forename: N J
authors.initials: NJ
authors.lastname: Shivaramu
authors.affiliation: Department of Physics, Jnanabharathi Campus, Bangalore University, Bangalore 560 056, India. Electronic address: bnlnarasappa@rediffmail.com.
authors.forename: B N
authors.initials: BN
authors.lastname: Lakshminarasappa
authors.affiliation: Department of Physics (S & H), PES University, Bangalore 560085, India.
authors.forename: K R
authors.initials: KR
authors.lastname: Nagabhushana
authors.affiliation: Inter University Accelerator Centre, P.O. Box No. 10502, New Delhi 110 067, India.
authors.forename: Fouran
authors.initials: F
authors.lastname: Singh
keywords: Combustion synthesis; Electron spin resonance; FE-SEM; Photoluminescence; Radiation effects; Thermoluminescence