RESUMEN
In this work, Chemical Vapour Deposition (CVD) has been used to synthesize boron nitride (BN) nanostructures, particularly nanotubes, and selectively introduce defects into the lattice of the synthesized BN nanostructures through ion implantation. Scanning electron microscopy (SEM) images show clear evidence of BN nanostructures and BN nanotubes (BNNTs), with the latter appearing as long, thin structures with diameters ranging from â30-80 nm. Raman analysis show an E2g mode of vibration assigned to hexagonal BN (h-BN) at 1366 cm-1 after ion implantation, with increased intensity. Grazing incidence X-ray diffraction (GIXRD) spectra revealed a prominent peak between 54 and 56°, corresponding to the (004) h-BN reflection, which was used to determine the average lattice parameter câ0.662 nm representing the stacking direction of the BN layers. The majority of the samples had broad peaks, indicative of a nanocrystalline material. The only exception was the sample grown at 1200 °C, which was found to have a Scherrer crystallite size >100 nm. In contrast, the rest of the samples had an average size of 3.5 nm. Notable observations in this study include a significant rise in the size of the Raman derived crystallite domains in the nanostructures synthesized at 1100 and 1200 °C after ion implantation with boron ions at fluence 5 × 1014 ions/cm2.
RESUMEN
Quantitative analysis of materials from Heavy Ion PIXE spectra remains impeded by the lack of reliable X-ray production cross section (XPCS) data. Although efforts at experimental Heavy Ion induced XPCS measurements still continue, Multiple Ionisation (MI) effects, which are not fully described by theory, render simulations of heavy ion PIXE data unreliable for large Z1/Z2 collisions, especially at low energies. This is also exacerbated by the random selection of projectile-target combinations for measured and reported experimental data available to validate theory. This study explored heavy ion induced X-ray production cross section deviations from those induced by protons at the same ion velocity. This enabled evaluations of the degree to which cross sections are enhanced through MI effects, with the aim of predicting XPCS due to heavy ion impact. The evaluation was carried out through the scaling of experimental heavy ion to theoretical proton cross section ratios (R), which were then used for the interpolation of XPCS in the same target element for 'missing' projectiles within the range of evaluation. Here we present measurements of heavy ion induced total L-shell XPCS in Bi, carried out to determine HI/p MI induced deviations due to C, F, Cl and Ti projectiles at an ion velocity range of (0.2-1.0) MeV/nucleon.
RESUMEN
Experimental heavy ion induced X-ray production cross sections in matter continue to be of importance for both fundamental ion-atom collision studies as well as practical applications such as in nuclear analytical techniques. This work presents results of L-shell X-ray production cross section measurements in 89Y, 158Gd and 209Bi due to 4 MeV-12 MeV 12Cq + projectile ions. Experimental data are compared with theoretical calculations based on the ECPSSR, ECPSSR + EC and ECPSSR-UA models. Data show fairly good, albeit energy dependent agreement with the different models for yttrium and gadolinium cross sections. For bismuth, all three models overestimate data by an almost constant factor of two. The effect of multiple ionization on the l-line intensity ratios is also presented for gadolinium and bismuth targets.