Results 1 - 10 of 20
Results 1 - 10 of 20. Search took: 0.017 seconds
|Sort by: date | relevance|
[en] An electron cyclotron resonance (ECR) based medium energy ion beam facility, known as High Fluence Ion Beam Facility (HFIBF), is commissioned at Nanotechnology Application Centre, University of Allahabad. The facility is a user facility for ion beam driven materials synthesis, properties modification and their characterizations. The source can be operated up to maximum of 25 kV extraction and 300 kV platform potential and it includes RF plasma, oven and sputter ion sources for gases, low melting point metals and high melting points metal ions generations, respectively. The main advantages of the facility is the high flux and large area scanning. (author)
[en] The electronic sputtering of LiF thin films due to 120 MeV Ag9- irradiation has been studied. The sputtering yield of these films of different thicknesses deposited on different substrates is determined by elastic recoil detection analysis. We have studied the effect of the thickness of the film on the electronic sputtering process. The results show that the sputtering yield is of the order of 103 atoms/ion and the sputtering decreases with increasing thickness of the film. On the other hand, the film deposited on insulator substrate shows higher sputtering. These aspects are discussed in the framework of thermal spike model. (author)
[en] Present work deals with the comparative study of micro-structural and electrical properties of conventionally and microwave (MW) heat treated dysprosia stabilized zirconia electrolyte for solid oxide fuel cell application. Characterizations have been evaluated by means of X-ray diffraction (XRD) and scanning (SEM), and complex impedance analysis respectively. The amount of dysprosia was varied from 2 to 10 mol% in zirconia. The addition of dysprosia (8-10 mol % in conventionally sintered DySZ and 4-10 mol% in MW sintered DySZ) stabilized the cubic zirconia phase, which was analyzed from XRD analysis. SEM micrographs clearly showed the grain size but high density in MW sintered DySZ compare to conventionally sintered DySZ compounds. Complex impedance analysis was performed in the temperature range from 250 to 600℃. The results indicated a dominant contribution comes from grain boundary resistance by both ways heat treated DySZ samples. D.C. conductivity increases with dysprosia doping up to 6 mol% (conventional sintered) and 8 mol% (for MW sintered) and thereafter showing a reverse trend. Magnitude of DC conductivity found to be higher in MW sintered DySZ than conventional DySZ. (author)
[en] The angular distribution of the sputtering yield from highly oriented pyrolytic graphite sample irradiated with a 130 MeV Ag beam is studied. The beam was incident perpendicular to the sample and the sputtered carbon was collected on Si catcher foils which were studied using a high resolution ERDA set up. An anisotropic distribution of sputtering is observed with a distribution C=Acos1.3Θ+Bexp(-(Θ-53)2/σ2) which shows that a peak lies at around 53 deg. on a distribution which otherwise is a over-cosine function. The maximum sputtering yield is observed at 53 deg., falling rapidly to almost zero at 90 deg., with an average sputter yield of 5.5 x 105 atoms/ion. It is suggested that this anisotropy may be due to the crystal structure and formation of a pressure pulse
[en] Swift heavy ions induced effects on optical (color centers), structural and surface (electronic sputtering and morphology) modifications, in nano-grains LiF thin films were studied by glancing angle X-ray diffraction, optical absorption, photoluminescence and elastic recoil detection analysis techniques. Our results show that grain size and irradiation temperature play a crucial role in materials modifications as a function of fluence for the selected ion beam parameters. Also for the first time, lamellae formation was observed in LiF thin films after a high fluence irradiation of 5 x 1013 ions/cm2 at liquid nitrogen temperature with 120 MeV Ag ions irradiation under grazing incidence (∝10 ). (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
[en] Photoluminescence (PL) properties of swift heavy ions-induced F2 and F3+ color centers in nano-granular lithium fluoride (LiF) thin film were studied. LiF films were deposited on glass and silica substrates and irradiated with various ion species (Ag, Ni and Au) at different irradiation temperatures. The role of ion species, their fluence and the irradiation temperature on the PL intensity of color centers induced in LiF thin films is discussed
[en] The topographic and spectroscopic (I-V) characteristics of the defect structures created by SHI irradiation of HOPG and 60C using an ambient scanning tunneling microscope (STM) and an atomic force microscope (AFM), have been studied. Various types of defect structures on the surface of highly oriented pyrolytic graphite (HOPG) are observed. The results of spectroscopic studies of pristine and 110 MeV Ni ion irradiated C60 surface are also studied and the differential conductivity (dI/dV) as function of bias using lock-in amplifier of the irradiated sample shows a reduction in flat region implying a reduction in the band gap after irradiation besides an increase in the linearity of the non-linear characteristics. (author)
[en] Thermally grown thin films of LiF were irradiated with 150 MeV Ag ions at various fluences. The quality of films was studied using GAXRD, which shows that films are c-axis oriented. It also shows that grain size decreases and the intensity of (200) orientation enhances with fluence, which is the preferential orientation. These results are further confirmed by photoluminescence studies, which shows that the concentration of F3+ and F2 color centers decreases with ion fluence due to increase in surface to volume ratio under Swift Heavy Ion (SHI) irradiation. (author)
[en] The effect of 50 MeV Ni ion irradiation on Au/n-GaN Schottky diode has been studied by in situ current voltage characterization. The variation of Schottky parameters with ion irradiation is discussed by varying the irradiation fluence from 5 x 109 to 5 x 1011 ions cm-2. These results are interpreted on the basis of energy loss mechanisms of swift heavy ion (SHI) irradiation at the metal-semiconductor interface.
[en] Influence of substrate on electronic sputtering of fluoride (LiF, CaF2 and BaF2) thin films, 10 and 100 nm thin, under dense electronic excitation of 120 MeV Ag25+ ions irradiation is investigated. The sputtering yield of the films deposited on insulating (glass) and semiconducting (Si) substrates are determined by elastic recoil detection analysis technique. Results revealed that sputtering yield is higher, up to 7.4 x 106 atoms/ion for LiF film on glass substrate, than that is reported for bulk materials/crystals (∼104 atoms/ion), while a lower value of the yield (2.3 x 106 atoms/ion) is observed for film deposited on Si substrate. The increase in the yield for thin films as compared to bulk material is a combined effect of the insulator substrate used for deposition and reduced film dimension. The results are explained in the framework of thermal spike model along with substrate and size effects in thin films. It is also observed that the material with higher band gap showed higher sputtering yield.