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Nanocrystalline Y 2 O 3 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 Y 2 O 3 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, O 2 − and Y 2+ defects. A broad photoluminescence (PL) emission with peak at~386 nm is observed when the sample is excited with 252 nm. Thermoluminescence (TL) properties of γ-irradiated Y 2 O 3 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 Y 2 O 3 shows a prominent TL glow with peaks at 396 K and 590 K. Among the fuels, urea used Y 2 O 3 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.

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Ion beam analysis methods are very sensitive to analyze the defects and impurities in insulators and semiconductors. The present study focuses on an investigation of the nature of defects in monoclinic ZrO 2 and spectroscopic properties of ZrO 2 :Sm 3+ (1 mol %) phosphor using ionoluminescence (IL) under the excitation of 100 MeV Si 7+ ions. The structures of the combustion-synthesized ZrO 2 and ZrO 2 :Sm 3+ samples were revealed to be monoclinic as analyzed through X-ray diffraction, Raman spectroscopy, and selected area electron diffraction methods. Structural parameters were assessed utilizing Rietveld refinement of the obtained XRD data using GSAS II software. The average particle size of ZrO 2 and ZrO 2 :Sm 3+ samples was found to be 77 ± 2 and 72 ± 3 nm, respectively, as determined from transmission electron microscopy images. The electronic structure and the oxygen vacancy defect population were analyzed using experimental measurements [viz ionoluminescence (IL), photoluminescence (PL), PL lifetime decay, electron paramagnetic resonance (EPR), and diffuse reflectance spectroscopy (DRS)]. The prominent IL and PL emission peaks seen at 499 nm in monoclinic ZrO 2 are attributed to the F + type center that was assigned to the F 2 + centeran aggregate of the singly ionized oxygen vacancies. ZrO 2 :Sm 3+ (1 mol %) samples display Sm 3+ characteristic IL emission peaks between 562−582, 600−620, 635−673, and 719 nm, corresponding to ( 4 G 5/2 → 6 H 5/2 ), ( 4 G 5/2 → 6 H 7/2 ), ( 4 G 5/2 → 6 H 9/2 ), and ( 4 G 5/2 → 6 H 11/2 ) transitions under 100 MeV Si 7+ ion excitation for various fluences. The 100 MeV Si 7+ ion-induced ion track radius (damaged cross section) and local temperature were estimated through the thermal spike model to be 0.53 nm and 700 K (the duration is about 10 −13 second), respectively. CIE coordinates fall near the yellow color region and then slightly shift toward the green color region with an increase of fluence because of the lattice distortion and change of the Sm 3+ symmetry site.

Thermoluminescence (TL) of combustion-synthesized aluminum oxide bombarded with 120 MeV swift Au 9+ ions in the fluence range of 1 × 10 11 − 2 × 10 13 ions cm −2 has been studied at room temperature. Two TL glows-a well-resolved one with peak at ∼623 K (Tg 2 ) and another unresolved one at ∼513 K (Tg1)-are recorded at a heating rate of 10 K s −1 . It is found that the TL intensity increases with the fluence up to 1 × 10 13 ions cm −2 and then decreases with increase in fluence. Also, the prominent glow peak temperature (Tg 2 ) is found to be shifted towards the lower temperature region, while the TL intensity increases with the increase in ion fluence. In the case of heat-treated samples, the TL intensity is observed to be enhanced further. However, in the case of samples heat-treated beyond 973 K, the TL intensity is found to be decreased with the increase in heat treatment. The glow curves are analyzed by the glow curve deconvolution technique and trap parameters are estimated and discussed in this paper.

a b s t r a c tNanoparticles of pure yttrium oxide (Y 2 O 3 ) have been prepared by sol gel method. The powder X-ray diffraction (PXRD) pattern of as synthesized sample showed the amorphous nature. The as synthesized Y 2 O 3 powders are annealed at 500, 600, 700, 800 and 900°C for 2 h. Y 2 O 3 powder heat treated for 600°C showed cubic phase and the crystallite sizes are found to be $13 nm. Fourier transformed infrared spectroscopy (FTIR) revealed absorption with peaks at 3434, 1724, 1525, 1400, 847, 562 and 465 cm À1 . Photoluminescence (PL) of 100 MeV Si 8+ ion irradiated samples shows emission with peaks at 417, 432, 465 nm. It is found that PL intensity increases with increasing in ion fluence up to $3 Â 10 12 ions cm À2 and then decreases with further increase in ion fluence. A well resolved thermoluminescence (TL) glow with peak at $430 K (Tm 1 ) and an unresolved TL glow with peak at $538 (Tm 2 ), 584 K (Tm 3 ) are observed in ion irradiated samples.

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Polycrystalline aluminum oxide is synthesized by combustion technique and XRD studies of the sample revealed the α-phase. The synthesized sample is irradiated with 120 MeV swift Au 9+ ions for the fluence in the range from 1 × 10 11 to 1 × 10 13 ions cm -2 . A broad photoluminescence (PL) emission with peak at ~ 447 nm and two sharp emissions with peak at ~ 679 and ~ 695 nm are observed in pristine when sample was excited with 326 nm. However, in the irradiated samples the PL intensity at ~ 447, 679 and 695 nm decreases with increase in ion fluence. The α-Al 2 O 3 gives rise to seven Raman modes with Raman intensity with peaks at ~ 253, 396, 417, 546, 630, 842, 867 cm -1 observed in pristine. The intensity of these modes decreases with increase in ion fluence. However, the Raman modes observed at lower fluences are found to disappear at higher fluence.