Spectroscopic studies of swift heavy ion irradiated nanophase mullite

Photoluminescence (PL) studies of 100 MeV swift Ag8+ ion bombarded combustion synthesized nanophase mullite has been studied at room temperature (RT) and the results are reported here. A pair of PL bands, one broad band centres at â550 nm and another sharp one at â690 nm are observed with excitation by a 442 nm laser beam. However, when the sample is excited with 326 nm laser beam, three bands with peaks at â¼460, 550 and a well resolved one with peak at 760 nm are observed. It is observed that the PL intensity increases up to 5 à 1011 ions/cm2 and thereafter it decreases with increase of ion fluence. The pristine as well as Ag8+ ion irradiated mullites are characterized by infrared spectroscopy (IR) and X-ray diffraction (XRD) techniques. The decrease in PL intensity is attributed to Al-O and Si-O bonds present as the surface getting amorphized. The effects of Ag8+ irradiation are compared to those obtained with Ni8+ ions and the results are discussed. © 2005 Elsevier B.V. All rights reserved

Luminescence performance of europium-​doped yttrium oxide thin films

Europium-​doped yttrium oxide thin films have been deposited by a spray pyrolysis method. The crystallite sizes are calcd. to be ∼50 nm using Scherrer's formula. Fourier transformed IR spectroscopy (FTIR) reveals broad absorption with peak at 875 cm-​1. Surface morphol. and elemental compn. of the thin films are studied by a field-​emission scanning electron microscope (FESEM) equipped with energy dispersive X-​ray spectroscopy (EDS)​. The energy gap (Eg) of the thin film sample is found to be ∼5.37 eV. The film exhibits photoluminescence (PL) emission over 525-​550 nm, 585-​601 nm, 612 nm and 620-​632 nm under the excitation of 240 nm. Gamma (γ)​-​irradiated films exhibit two well-​resolved thermoluminescent (TL) glows with peaks at 460 and 570 K. The TL glow curves are analyzed by a glow curve shape method. The activation energy and the frequency factor are found to be, resp., ∼0.6 eV, ∼3×106 s-​1 for 460 K and ∼0.53 eV, ∼46.72×103 s-​1 for 570 K

Thermoluminescence studies in swift heavy ion irradiated aluminum oxide

Thermoluminescence (TL) of combustion-synthesized aluminum oxide bombarded with 120 MeV swift Au9 + ions in the fluence range of 1 à 1011 - 2 à 1013 ions cm- 2 has been studied at room temperature. Two TL glows-a well-resolved one with peak at ⼠623 K(Tg2) and another unresolved one at ⼠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 à 1013 ions cm- 2 and then decreases with increase in fluence. Also, the prominent glow peak temperature (Tg2) 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. © 2008 Elsevier Ltd. All rights reserved

Thermoluminescence Studies of γ-Irradiated ZnO:Mg2+ Nanoparticles

Pure and Mg2+ doped ZnO nanoparticles are synthesized by solution combustion method. X-ray diffraction studies of the samples confirm hexagonal phase. Crystallite size is calculated using Scherer formula and found to be ∼30 nm for undoped ZnO and 34–38 nm for Mg2+ doped ZnO. A broad PL emission in the range 400–600 nm with peaks at 400, 450, 468, 483, 492, 517, 553 nm are observed in both pure and Mg2+ doped nanoparticles. Near band edge emission of ZnO is observed at 400 nm. The broad band emissions are due to surface defects. PL emission intensity is found to increase with Mg2+ concentration up to 1.5 mol% and then decreases due to concentration quenching. Samples are irradiated with γ-rays in a dose range 0.05–8 kGy. Gamma irradiation doesn’t affect PL properties. Undoped samples exhibit unstructured low intense TL glow with peak at 720 K. Whereas Mg2+ doped samples exhibit well structured TL glow curves with peak at ∼618 K. TL glow peak intensity of Mg2+ doped samples increases with Mg2+ concentration up to 2 mol%, thereafter decreases. TL curves of Mg2+ (2 mol%) doped ZnO exhibit two glows, a high intense peak at 618 K and a weak one with peak at ∼485 K. TL intensity of Mg2+ (2 mol%) doped ZnO samples increases with gamma dose up to 1 kGy and then decreases. Kinetic parameters of TL glows are calculated by deconvolution technique. Activation energy and frequency factor are found to be 1.5 eV and 3.38 × 1011 s−1 respectively

SHI induced thermoluminescence properties of sol-gel derived Y2O3:Er3+ nanophosphor

Nanocrystalline erbium doped yttrium oxide (Y2O3:Er3+) was synthesized by the sol-gel technique using citric acid as complexing agent. The synthesized samples were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM) techniques for phase-purity and microstructure. Er3+ doped Y2O3 crystallizes in cubic phase with an average crystallite size of 24.3 nm. The pellets of Y2O3:Er3+ were irradiated with 100 MeV swift Si8+ ions with fluence in the range of 3×1011 - 3×1013 ions cm-2. Three well resolved thermoluminescence (TL) glows with peaks at ~422, 525 and 620 K were observed in Er3+ doped Y2O3 samples. It was observed that the TL intensity was found to increases with increasing Er3+ concentration up to 0.4 mol% in Y2O3 and thereafter it decreases with further increase of Er3+ concentration. Also, the intensity of low temperature TL glow peak (~422 K) increases with increasing ion fluence up to 1×1012 ions cm-2 and decreases with further increase of ion fluences. The TL trap parameters were calculated by glow curve shape method and the deconvoluted glows were exhibit of second order kinetics. Copyright © 2015 VBRI press. - See more at

Ion Beam Induced Cubic To Monoclinic Phase Transformation of Nanocrystalline Yttria

Sol gel derived nanocrystalline yttria pellets are irradiated with 120 MeV Ag9+ ions for fluence in the range 1 � 1012–3 � 1013 ions cm2 . Pristine and irradiated samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. XRD pattern of pristine Y2O3 nanocrystal reveal cubic structure. A new XRD peak at 30.36� is observed in pellet irradiated with 1 � 1013 ions cm2 . The peak at 30.36� is corresponding to ð4 0 � 2Þ plane of monoclinic phase. The diffraction intensity of ð4 0 � 2Þ plane increases with Ag9+ ion fluence. Raman spectrum of pristine pellet show bands corresponding to cubic phase. And, ion irradiated sample show new peaks at 410, 514 and 641 cm1 corresponding monoclinic phase. HR-TEM and SAED pattern of ion irradiated sample confirmed the presence of monoclinic phase. Hence, it is confirmed that, 120 MeV Ag9+ ions induce phase transformation in nanocrystalline Y2O3

Ion beam induced luminescence studies of sol gel derived Y2O3:Dy3+ nanophosphors

Pure and Dy3+ doped Y2O3 are prepared by sol-gel technique. The samples are annealed at 900 °C to obtain crystalline phase. X-ray diffraction (XRD) patterns confirm cubic phase of Y2O3. The crystallites size is calculated using Scherrer formula and is found to be in the order of 29.67 nm. The particles are found to be spherical in nature and their sizes are estimated to be 35 nm by scanning electron microscope (SEM) technique. Online ionoluminescence (IL) spectra of pure and Dy3+ doped Y2O3 are recorded with 100 MeV Si8+ ions with fluence in the range 0.375-6.75×1013 ions cm-2. Undoped samples do not show IL emission for any of the fluence explored. Four prominent IL emissions with peaks at 488, 670, 767 nm and a prominent pair at 574 and 584 nm are observed in Dy3+ doped samples. These characteristic emissions are attributed to luminescence centers activated by Dy3+ ions due to 4F9/2→6H15/2, 4F9/2→6H11/2, 4F9/2→6H9/2+6H11/2 and 4F9/2→6H13/2 transitions respectively. Further, it is found that IL intensity at 574 nm decays rapidly with ion fluence. A broad and weak photoluminescence (PL) emission with peak at ~485 nm and a strong emission at 573 nm are observed in ion irradiated Y2O3:Dy3+. It is found that PL intensity increases with ion fluence up to 3×1010 ions cm-2 and then it decreases with further increase of ion fluence. This may be attributed to lattice disorder produced by dense electronic excitation under swift heavy ion irradiation. © 2015 Elsevier B.V

Synthesis characterization and luminescence studies of gamma irradiated nanocrystalline yttrium oxide

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 nmfor samples synthesized using urea and 15–20 nm for samples synthesized using glycine respectively. Field emissionscanning electron microscopy (FE-SEM) image of 1173 K annealed Y2O3 samples show well separated sphericalshape 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 Y2+ 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 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 (Im1) 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 detai

Optical absorption and thermoluminescence studies in 100MeV swift heavy ion irradiated CaF 2 crystals

Pure and Ytterbium (Yb) doped Calcium fluoride (CaF2) single crystals were irradiated with 100 MeV Ni7+ ions for fluences in the range 5 × 1011–2.5 × 1013 ions cm−2. The irradiated crystals were characterized by Optical absorption (OA) and Thermoluminescence (TL) techniques. The OA spectra of ion irradiated pure CaF2 crystals showed a broad absorption with peak at ∼556 nm and a weak one at ∼220 nm, whereas the Yb doped crystals showed two strong absorption bands at ∼300 and 550 nm. From the study of OA spectra, the defect centers responsible for the absorption were identified. TL measurements of Ni7+ ion irradiated pure CaF2 samples indicated a strong TL glow with peak at ∼510 K. However, the Yb doped crystals showed two TL glows at ∼406 and 496 K. The OA and TL intensity were found to increase with increase of ion fluence upto 1 × 1013 ions cm−2 and thereafter it decreased with further increase of fluence. The results obtained are discussed in detail

Synthesis characterization and luminescence studies of 100 MeV Si 8+ ion irradiated sol gel derived nanocrystalline Y2O 3

Nanoparticles of pure yttrium oxide (Y2O3) 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 Y2O3 powders are annealed at 500, 600, 700, 800 and 900 °C for 2 h. Y2O3 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−1. Photoluminescence (PL) of 100 MeV Si8+ 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 × 1012 ions cm−2 and then decreases with further increase in ion fluence. A well resolved thermoluminescence (TL) glow with peak at ∼430 K (Tm1) and an unresolved TL glow with peak at ∼538 (Tm2), 584 K (Tm3) are observed in ion irradiated samples