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Coupled Chemical Reactions in Dynamic Nanometric Confinement
Published in Kevin Yallup, Krzysztof Iniewski, Technologies for Smart Sensors and Sensor Fusion, 2017
Dietmar Fink, G. Muñoz Hernandez, H. García Arellano, W.H. Fahrner, K. Hoppe, J. Vacik
It is well known that the etching of a swift heavy ion track from one side only leads to the formation of an asymmetric nanopore that is conical in a crude first approximation and funnel-like in a much better description [20]. When following the etchant processes by measuring a test current through the tracks upon application of a constant dc or ac voltage, one starts recording remarkable currents only from the moment of etchant breakthrough on, as from this moment on the electrolyte’s ions are enabled to pass freely across the foil from one side to the other.
Electronic ionisation-induced annealing of pre-existing defects in Al2O3 and CaF2 single crystals
Published in Philosophical Magazine, 2022
M. Izerrouken, R. Hazem, S. Kuzeci, C. Tav, U. Yahsi, S. Limam
As well known, when a swift heavy ion penetrates in solid, it loses energy via the inelastic collisions process (electronic stopping power) with the atomic electrons and elastic collisions process (nuclear stopping power). During the inelastic collisions process, the energy is transferred to the target atom through ionisation and excitation of the surrounding electrons. This process is the primary mechanism responsible for defect formation in materials by swift heavy ions. It can also anneal the pre-existing defects as mentioned above in the introduction. Though, this strongly depends on the properties of the traversed materials. Several models were proposed for the description of ionisation-induced damage formation in materials. Coulomb explosion model [35, 36], thermal spike model [37–39], and excitonic model [40–42]. In the two latter models, the electron–phonon coupling plays a crucial role in the defect formation induced by swift heavy ions [43]. As indicated by the thermal spike model, the energy is first deposited on the electron and subsequently transferred to the atomic subsystems via electron–phonon coupling, which results in the heating of the lattice to a temperature above the melting point. Then, this is followed by rapid quenching, resulting in amorphous track formation. The evolution of track radii is predicted in several materials which coincide with the experimental data [44]. This model explains well the defect annealing and defect formation in materials [45].
Tuning the properties of Fe-BTC metal-organic frameworks (MOFs) by swift heavy ion (SHI) irradiation
Published in Radiation Effects and Defects in Solids, 2021
Pasha W. Sayyad, Nikesh N. Ingle, Gajanan A. Bodkhe, Megha A. Deshmukh, Harshada K. Patil, Sumedh M. Shirsat, Fouran Singh, Mahendra D. Shirsat
There are many reports on the polymers, oxides, and other materials based on SHI irradiation, which causes reduction in the optical band gap for various applications (15–17). A similar approach was studied for the modulation of the energy bandgap by SHI irradiated metal–organic framework. There are different factors that affect the band gap viz. intra-chain charge transfer, bond-length alternation, aromaticity, substituents effects, intermolecular interactions, and π-conjugation length (18). Therefore, the swift heavy ion (SHI) irradiation is a very effective method to induce structural/microstructural modifications in the materials. It has been employed to tailor the properties of various materials, including insulators, metals, semiconductors (16,19–21). The low toxicity and the high biocompatibility of iron-based MOFs awakened the highest interest which is widely attracting as a photocatalyst applications (22).
Synthesis and modification of ZnO thin films by energetic ion beams
Published in Radiation Effects and Defects in Solids, 2021
Richa Krishna, Dinesh Chandra Agarwal, Devesh Kumar Avasthi
When the ion energy is around or higher than 1 MeV/nucleon, its velocity is of the order of Bohr electron velocity or higher. Such high velocity ions are referred to as swift heavy ions (SHI) and they pass through the matter very swiftly, either ionizing or exciting the atoms. In this way, the ion leaves behind a trail of excited atoms along its path. The temperature of this region increases tremendously termed as the thermal spike leading to a transiently molten track which, on ultra-fast quenching rate of 1014 K/s, results in a narrow cylindrical defected zone, known as columnar defect or ion track. Especially for insulator, the ion track formation occurs via Coulombic repulsion of positive ions surrounding ion path and is known as Coulomb explosion. The formation of ion track or latent track occurs in all the insulators and most of the semiconductors by SHI, whereas the metals (except Fe, Ti, Bi etc.) are not affected by SHI and the latent track formation does not occur in these. The value of Se where the formation of ion track starts to begin is called threshold Se and its value varies from material to material. Although the formation of ion track does not occur in all the materials by swift heavy ions, defect creation or defect annealing can occur. In some carbon nanostructures it is shown that each incident ion produces defects in the central core of ion path and annealing of defects occurs in the halo region surrounding the ion track region (24–28).