In this research, we seek a new superconducting candidate LaAlYbCuO based on the need to improve upon the lanthanum cuprates framework. LaAlYbCuO high temperature superconductor was prepared by ...standard solid-state reaction. The characterization was done by the X-ray powder diffraction technique, Scanning Electron Microscopy (SEM) and Rutherford Backscattering Spectrometry (RBS). The analysis of the images was done using Match, Vesta, SRIM, CERN-Root, OMDAQ and Gwydion software. The XRD refinements show that LAYbCO has orthorhombic structure with unit cell as a = 3.865 Å, b = 3.865 Å, c = 19.887 Å. The specimen had theta correction of 0.19891°. The ratio of electron to phonon production in LAYbCO is approximately 999:1. However, this does not rule-out the possibility of electron-phonon interaction. The elemental composition of LAYbCO is given as La1.35Al3.97 Yb6.80Cu6.80O15 at Q-factor – 0.033, Chi-square – 0.6057 and dMax – 173. The new LAYbCO framework showed high chemical homogeneity. It was discovered that natural inclination of the atomic structure is quite important for structural interpretations.
The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of ...the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy and light yield analysis whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs and light loss can be attributed to a breakdown in the light transfer between base and fluor dopants. For doses of 8 MGy to 80 MGy, structural damage leads to possible hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss and light yield loss with increasing dose.
This work investigates the feasibility of using low-temperature ion irradiation to partially anneal implantation defects in polymeric materials, with the goal of improving their structural and ...optical properties. In this experiment, polyethylene terephthalate (PET) films were initially implanted with 150 keV 107Ag+ ions at fluences of either 1.00 ×1016 or 5.00 ×1016 ions/cm2 and then irradiated with 14 MeV 28Si4+-ions at a fluence of 2.40 ×1013 ions/cm2. The effects of swift heavy ion irradiation on the annealing of Ag-implanted PET films were examined at two different temperatures: room temperature and cryogenic temperature. The latter was chosen to minimise thermal diffusion and enhance defect or crystallinity recovery. The examination was conducted using X-ray diffraction (XRD), Raman and Ultraviolet–visible (UV–Vis) spectroscopies. The XRD patterns showed attenuation and slight shifts in peak positions with increasing implantation fluence, suggesting changes in the semi-crystallinity of PET to the amorphous phase. Crystallinity was found to decrease with an increase in implantation fluence, which could be ascribed to Ag- and Si-induced defects in the PET samples. The peak intensities of samples irradiated at room and low temperatures exhibited a net difference in peak intensity, indicating a partial recovery of the crystallinity for the low temperature irradiated samples. The observed large G band in Raman spectra indicates the presence of amorphous and graphite-like structures in the samples, which also vary depending on the irradiation type. The UV–Vis spectra of Ag-implanted and 14 MeV Si-irradiated PET sheets exhibit a decreasing trend in the optical bandgap, not only with increasing implantation fluence as expected, but also as the Si-irradiation temperature is changed from room- to cryogenic temperature. The Urbach energy calculation showed an increase in disorder in implanted and irradiated sample types. The Urbach energy for the low-temperature irradiation is higher than that of room-temperature irradiation. The increase in disorder for low-temperature irradiation was attributed to localised defect creation due to the confinement of energy spread in the cooled samples. These results suggest that low-temperature ion irradiation is a promising technique for annealing out ion implantation defects and achieving crystallinity levels that are difficult to attain by conventional means in polymers.
•Effects of heavy ion room versus low temperature irradiations on PET were studied.•14 MeV Si-beam was employed at a constant irradiation dose of 2.40×1013 ions/cm2.•X-ray diffraction studies show recovery of crystallinity for low temperature investigations.•Raman studies showed more accumulation of C-atoms at the surface layers for Room temperature.•UV–Vis studies showed decreases in the energy bandgap and the efficacity of low temperatures irradiation was observed.
The radiation damage in polyvinyl toluene based plastic scintillator EJ200 obtained from ELJEN technology was investigated. This forms part of a comparative study conducted to aid in the upgrade of ...the Tile Calorimeter of the ATLAS detector during which the Gap scintillators will be replaced. Samples subjected to 6 MeV proton irradiation using the tandem accelerator of iThemba LABS, were irradiated with doses of approximately 0.8 MGy, 8 MGy, 25 MGy and 80 MGy. The optical properties were investigated using transmission spectroscopy whilst structural damage was assessed using Raman spectroscopy. Findings indicate that for the dose of 0.8 MGy, no structural damage occurs but a breakdown in the light transfer between base and fluor dopants is observed. For doses of 8 MGy to 80 MGy, structural damage leads to hydrogen loss in the benzene ring of the PVT base which forms free radicals. This results in an additional absorptive component causing increased transmission loss as dose is increased.
Successful co-implementation of different heavy ion beam nuclear analytical techniques such as heavy ion PIXE, ERDA, MeV SIMS and RBS hinges on the availability of accurate databases of fundamental ...ion beam-matter interaction parameters. We report on measurements carried out to determine L-shell X-ray production cross sections in 101Ru and 181Ta due to 12C, 16O and 28Si projectile ions in the 0.2 MeV/u–1.0 MeV/u energy range. Experimental data is compared to calculations by one of the most widely implemented X-ray ionisation theories in PIXE analyses – the ECPSSR theory in its modified United Atom (UA) version. Results show fairly good agreement between experiment and theory for the 181Ta target atoms, with the level of agreement improving as the Zion/Ztarget ratio decreases and as beam energy increases. For 101Ru target atoms theoretical predictions tend to underestimate experimental data and the discrepancies increase with projectile mass and decreasing energy. The contribution of projectile electron capture (EC) to the measured X-ray production cross sections is also considered in the data analysis and discussion.
Ion beam induced modification of thin metallic films is an emerging approach to grow metallic nanoparticles controllably. Modification of thin solid films is helpful in fabricating arrays of ...nanoscale particles for electronic and photonic devices and for the catalyzed synthesis of nanotubes and nanowires. In this work, the modification and nanostructures formation over the surface of SiC/Pd thin films of 15 and 45 nm thicknesses, grown on crystalline Silicon (c-Si) substrate by electron beam deposition, upon ion irradiation, have been investigated by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Rutherford backscattering spectrometry (RBS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. The SiC/Pd bilayer films were irradiated with 100 keV Ar+ ions at fluences of 1 × 1015 and 5 × 1015 ions/cm2 at room temperature. The surface morphology from SEM analysis showed the formation of nanoparticles that were interconnected after irradiation. The RBS and EDS results confirmed the presence of Pd, C, O and Si. While the Raman spectrum of the pristine sample displayed only a sharp peak at 520 cm−1 characteristic to c-Si substrate, the spectra of the irradiated sample red-shifted to lower wavenumbers indicating the appearance of Si nanocrystals.. Hence, ion beam irradiation is a promising method for the fabrication of SiC nanostructures on c-Si substrate.
Silicon (Si) has been the most widely used semiconductor for decades, playing an important role in the field of electronics, energy conversion and energy storage. Because of their unique ...morphological energy band characteristics, Si nanostructures exhibit superior performance in many applications in comparison with their bulk counterparts. In this study, the effects of thermal annealing on elemental composition and morphological properties of palladium metal thin films grown on c-Si substrates were investigated. Palladium (Pd) thin films of different thicknesses were deposited on Si (1 0 0) with and without native oxide layers by electron beam evaporation and annealed in vacuum at 600 °C for two hours. Scanning electron microscopy (SEM) studies have shown that the surface morphology showed an effective dewetting in individual droplets and islands which further coalesce into bigger islands. Rutherford backscattering spectrometry (RBS) and electrical measurements analyses revealed the diffusion of the Si substrate into the Pd layer during annealing. This contribution will discuss the effects of the metal layer thickness as well as the native oxide on the metal thin films.
PDF
