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Sol gel derived nanocrystalline yttria pellets are irradiated with 120 MeV Ag 9+ ions for fluence in the range 1 × 10 12 –3 × 10 13 ions cm −2 . Pristine and irradiated samples are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. XRD pattern of pristine Y 2 O 3 nanocrystal reveal cubic structure. A new XRD peak at 30.36° is observed in pellet irradiated with 1 × 10 13 ions cm −2 . The peak at 30.36° is corresponding to ( 4 0 2 ¯ ) plane of monoclinic phase. The diffraction intensity of ( 4 0 2 ¯ ) plane increases with Ag 9+ 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 cm −1 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 Ag 9+ ions induce phase transformation in nanocrystalline Y 2 O 3 . [ABSTRACT FROM AUTHOR]

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 2h. Y2O3 powder heat treated for 600°C showed cubic phase and the crystallite sizes are found to be ∼13nm. Fourier transformed infrared spectroscopy (FTIR) revealed absorption with peaks at 3434, 1724, 1525, 1400, 847, 562 and 465cm−1. Photoluminescence (PL) of 100MeV Si8+ ion irradiated samples shows emission with peaks at 417, 432, 465nm. It is found that PL intensity increases with increasing in ion fluence up to ∼3×1012 ionscm−2 and then decreases with further increase in ion fluence. A well resolved thermoluminescence (TL) glow with peak at ∼430K (Tm1) and an unresolved TL glow with peak at ∼538 (Tm2), 584K (Tm3) are observed in ion irradiated samples. [ABSTRACT FROM AUTHOR]

Abstract: Pure and Ytterbium (Yb) doped Calcium fluoride (CaF2) single crystals were irradiated with 100MeV Ni7+ ions for fluences in the range 5×1011–2.5×1013 ionscm−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 ∼556nm and a weak one at ∼220nm, whereas the Yb doped crystals showed two strong absorption bands at ∼300 and 550nm. 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 ∼510K. However, the Yb doped crystals showed two TL glows at ∼406 and 496K. The OA and TL intensity were found to increase with increase of ion fluence upto 1×1013 ionscm−2 and thereafter it decreased with further increase of fluence. The results obtained are discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Al2O3 thin films find wide applications in optoelectronics, sensors, tribology etc. In the present work, Al2O3 films prepared by electron beam evaporation technique are irradiated with 100MeV swift Si7+ ions for the fluence in the range 1×1012 to 1×1013 ionscm−2 and the structural properties are studied by glancing angle X-ray diffraction. It shows a single diffraction peak at 38.2° which indicates the γ-phase of Al2O3. Further, it is observed that as the fluence increases up to 1×1013 ionscm−2 the diffraction peak intensity decreases indicating amorphization. Surface morphology studies by atomic force microscopy show mean surface roughness of 34.73nm and it decreases with increase in ion fluence. A strong photoluminescence (PL) emission with peak at 442nm along with shoulder at 420nm is observed when the samples are excited with 326nm light. The PL emission is found to increase with increase in ion fluence and the results are discussed in detail. [Copyright &y& Elsevier]

Abstract: E-beam evaporated aluminum oxide films were irradiated with 120MeV swift Au9+ ions in order to induced nanostructure formation. Atomic force microscope (AFM) results showed the formation of nanostructures for films irradiated with a fluence of 1×1013 ionscm−2. The particle size estimated by section analysis of the irradiated film was in the range 25–30nm. Glancing angle X-ray diffraction (GAXRD) revealed the amorphous nature of the films. Two strong Photoluminescence (PL) emission bands with peaks at ∼430nm and ∼645nm besides a shoulder at ∼540nm were observed in all irradiated samples. The PL intensity is found to increase with increase of ion fluence. [Copyright &y& Elsevier]

Abstract: Thermoluminescence (TL) of kyanite single crystals bombarded with 100MeV swift Ag8+ and Si8+ ions with fluences in the range 1×1011–5×1014 ions/cm2 has been studied at room temperature (RT). Two TL glows with peaks one at ∼445K and another one at ∼550K are recorded in Si8+ ion bombarded kyanite single crystals at a warming rate of 20Kmin−1. It is observed that the TL peak intensity increases with increase of ion fluence. This may be attributed to the creation of new traps during bombardment process. However, in the case of Ag8+ ion bombarded samples, a single well resolved glow with peak at ∼520K is observed in all the samples. Also, photoluminescence (PL) of Ag8+ ion irradiated kyanite single crystals have been studied and it is observed that a pair of sharp as well as strong PL emission bands with peaks at ∼688 and 706nm along with a broad emission band in the region 710–800nm at an excitation of 442nm laser beam. It is found that PL intensity decreases with increase of ion fluence. The decrease in intensity with increase of ion fluence is attributed to amorphization of the sample. [Copyright &y& Elsevier]

Photoluminescence (PL) of pelletized mullite samples irradiated with 100 MeV swift Ni8+ ions with fluences in the range 1 × 1011–5 × 1013 ions/cm2 have been studied at RT. A broad and strong PL emission band with peak at ∼537 nm besides a sharp emission band with peak at ∼705 nm have been recorded in combustion synthesized mullite. However, a single broad emission with peak at ∼537 nm have been recorded in mullite synthesized by sol–gel technique at an excitation of 442 nm laser beam. It is found that PL intensity is decreases with increase of Ni8+ ion fluence. The decrease in PL intensity is attributed to destruction of Al–O and Si–O bonds in the samples. Infrared absorption (IR) studies of as it is and Ni8+ ion irradiated mullites have also been studied and results obtained are discussed. [Copyright &y& Elsevier]

Abstract: Photoluminescence (PL) studies of 100MeV 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 ∼550nm and another sharp one at ∼690nm are observed with excitation by a 442nm laser beam. However, when the sample is excited with 326nm laser beam, three bands with peaks at ∼460, 550 and a well resolved one with peak at 760nm are observed. It is observed that the PL intensity increases up to 5×1011 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. [Copyright &y& Elsevier]