Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userStructural defects induced by Fe-ion implantation in TiO2
126
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
X-ray photoelectron spectroscopy (XPS) and resonant x-ray emission spectroscopy (RXES) measurements of pellet and thin film forms of TiO$_2$ with implanted Fe ions are presented and discussed. The findings indicate that Fe-implantation in a TiO$_2$ pellet sample induces heterovalent cation substitution (Fe$^{2+}rightarrow$ Ti$^{4+}$) beneath the surface region. But in thin film samples, the clustering of Fe atoms is primarily detected. In addition to this, significant amounts of secondary phases of Fe$^{3+}$ are detected on the surface of all doped samples due to oxygen exposure. These experimental findings are compared with density functional theory (DFT) calculations of formation energies for different configurations of structural defects in the implanted TiO$_2$:Fe system. According to our calculations, the clustering of Fe-atoms in TiO$_2$:Fe thin films can be attributed to the formation of combined substitutional and interstitial defects. Further, the differences due to Fe doping in pellet and thin film samples can ultimately be attributed to different surface to volume ratios.
rate research
Read More
The results of combined experimental and theoretical study of substitutional and clustering effects in Bi-doped TiO2 hosts (bulk and thin-film morphologies) are presented. Bi-doping of the bulk and thin-film titanium dioxide was made with help of pulsed ion-implantation (E(Bi+) = 30 keV, D = 1 * 1017 cm-2) without posterior tempering. The X-ray photoelectron spectroscopy (XPS) qualification (core-levels and valence bands) and Density-Functional Theory (DFT) calculations were employed in order to study the electronic structure of Bi-ion implanted TiO2 samples. According to XPS data obtained and DFT calculations, the Bi -> Ti cation substitution occurs in Bi-implanted bulk TiO2, whereas in the thin-film morphology of TiO2:Bi the Bi-atoms have metal-like clusters segregation tendency. Based on the combined XPS and DFT considerations the possible reasons and mechanism for the observed effects are discussed. It is believed that established peculiarities of bismuth embedding into employed TiO2 hosts are mostly the sequence of pleomorphic origin for the formed bismuth-oxygen chemical bonding.
Tungsten is the main candidate material for plasma-facing armour components in future fusion reactors. Bombardment with energetic fusion neutrons causes collision cascade damage and defect formation. Interaction of defects with helium, produced by transmutation and injected from the plasma, modifies defect retention and behaviour. Here we investigate the residual lattice strains caused by different doses of helium-ion-implantation into tungsten and tungsten-rhenium alloys. Energy and depth-resolved synchrotron X-ray micro-diffraction uniquely permits the measurement of lattice strain with sub-micron 3D spatial resolution and ~10-4 strain sensitivity. Increase of helium dose from 300 appm to 3000 appm increases volumetric strain by only ~2.4 times, indicating that defect retention per injected helium atom is ~3 times higher at low helium doses. This suggests that defect retention is not a simple function of implanted helium dose, but strongly depends on material composition and presence of impurities. Conversely, analysis of W-1wt% Re alloy samples and of different crystal orientations shows that both the presence of rhenium, and crystal orientation, have comparatively small effect on defect retention. These insights are key for the design of armour components in future reactors where it will be essential to account for irradiation-induced dimensional change when predicting component lifetime and performance.
In this paper, we discuss the results of our study of the synthesis of endohedral iron-fullerenes. A low energy Fe+ ion beam was irradiated to C60 thin film by using a deceleration system. Fe+-irradiated C60 thin film was analyzed by high performance liquid chromatography and laser desorption/ionization time-of-flight mass spectrometry. We investigated the performance of the deceleration system for using a Fe+ beam with low energy. In addition, we attempted to isolate the synthesized material from a Fe+-irradiated C60 thin film by high performance liquid chromatography.
Optically addressable spin defects in wide-bandage semiconductors as promising systems for quantum information and sensing applications have attracted more and more attention recently. Spin defects in two-dimensional materials are supposed to have unique superiority in quantum sensing since their atomatic thickness. Here, we demonstrate that the negatively boron charged vacancy (V$ _text{B}^{-} $) with good spin properties in hexagonal boron nitride can be generated by ion implantation. We carry out optically detected magnetic resonance measurements at room temperature to characterize the spin properties of V$ _text{B}^{-} $ defects, showing zero-filed splitting of $ sim $ 3.47 GHz. We compare the photoluminescence intensity and spin properties of V$ _text{B}^{-} $ defects generated by different implantation parameters, such as fluence, energy and ion species. With proper parameters, we can create V$ _text{B}^{-} $ defects successfully with high probability. Our results provide a simple and practicable method to create spin defects in hBN, which is of great significance for integrated hBN-based devices.
Focussed Ion Beam (FIB) milling is a mainstay of nano-scale machining. By manipulating a tightly focussed beam of energetic ions, often gallium (Ga+), FIB can sculpt nanostructures via localised sputtering. This ability to cut solid matter on the nano-scale has revolutionised sample preparation across the life-, earth- and materials sciences. For example FIB is central to microchip prototyping, 3D material analysis, targeted electron microscopy sample extraction and the nanotechnology behind size-dependent material properties. Despite its widespread usage, detailed understanding of the functional consequences of FIB-induced structural damage, intrinsic to the technique, remains elusive. Here, we present nano-scale measurements of three-dimensional, FIB-induced lattice strains, probed using Bragg Coherent X-ray Diffraction Imaging (BCDI). We observe that even low gallium ion doses, typical of FIB imaging, cause substantial lattice distortions. At higher doses, extended self-organised defect structures appear, giving rise to stresses far in excess of the bulk yield limit. Combined with detailed numerical calculations, these observations provide fundamental insight into the nature of the damage created and the structural instabilities that lead to a surprisingly inhomogeneous morphology.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
