Modification of SiO₂, ZnO, Fe₂O₃ and TiN Films by Electronic Excitation under High Energy Ion Impact

It has been known that the modification of non-metallic solid materials (oxides, nitrides, etc.), e.g., the formation of tracks, sputtering representing atomic displacement near the surface and lattice disordering are induced by electronic excitation under high-energy ion impact. We have investigated lattice disordering by the X-ray diffraction (XRD) of SiO2, ZnO, Fe2O3 and TiN films and have also measured the sputtering yields of TiN for a comparison of lattice disordering with sputtering. We find that both the degradation of the XRD intensity per unit ion fluence and the sputtering yields follow the power-law of the electronic stopping power and that these exponents are larger than unity. The exponents for the XRD degradation and sputtering are found to be comparable. These results imply that similar mechanisms are responsible for the lattice disordering and electronic sputtering. A mechanism of electron–lattice coupling, i.e., the energy transfer from the electronic system into the lattice, is discussed based on a crude estimation of atomic displacement due to Coulomb repulsion during the short neutralization time (~fs) in the ionized region. The bandgap scheme or exciton model is examined

Modification of Cu Oxide and Cu Nitride Films by Energetic Ion Impact

We have investigated lattice disordering of cupper oxide (Cu2O) and copper nitride (Cu3N) films induced by high- and low-energy ion impact, knowing that the effects of electronic excitation and elastic collision play roles by these ions, respectively. For high-energy ion impact, degradation of X-ray diffraction (XRD) intensity per ion fluence or lattice disordering cross-section (YXD) fits to the power-law: YXD = (BXDSe)NXD, with Se and BXD being the electronic stopping power and a constant. For Cu2O and Cu3N, NXD is obtained to be 2.42 and 1.75, and BXD is 0.223 and 0.54 (kev/nm)−1. It appears that for low-energy ion impact, YXD is nearly proportional to the nuclear stopping power (Sn). The efficiency of energy deposition, YXD/Se, as well as Ysp/Se, is compared with YXD/Sn, as well as Ysp/Sn. The efficiency ratio RXD = (YXD/Se)/(YXD/Sn) is evaluated to be ~0.1 and ~0.2 at Se = 15 keV/nm for Cu2O and Cu3N, meaning that the efficiency of electronic energy deposition is smaller than that of nuclear energy deposition. Rsp = (Ysp/Se)/(Ysp/Sn) is evaluated to be 0.46 for Cu2O and 0.7 for Cu3N at Se = 15 keV/nm

Modification of SiO2, ZnO, Fe2O3 and TiN Films by Electronic Excitation under High Energy Ion Impact

It has been known that the modification of non-metallic solid materials (oxides, nitrides, etc.), e.g., the formation of tracks, sputtering representing atomic displacement near the surface and lattice disordering are induced by electronic excitation under high-energy ion impact. We have investigated lattice disordering by the X-ray diffraction (XRD) of SiO2, ZnO, Fe2O3 and TiN films and have also measured the sputtering yields of TiN for a comparison of lattice disordering with sputtering. We find that both the degradation of the XRD intensity per unit ion fluence and the sputtering yields follow the power-law of the electronic stopping power and that these exponents are larger than unity. The exponents for the XRD degradation and sputtering are found to be comparable. These results imply that similar mechanisms are responsible for the lattice disordering and electronic sputtering. A mechanism of electron–lattice coupling, i.e., the energy transfer from the electronic system into the lattice, is discussed based on a crude estimation of atomic displacement due to Coulomb repulsion during the short neutralization time (~fs) in the ionized region. The bandgap scheme or exciton model is examined

Difference in stopping cross section factor for He-4 ions between polycrystalline diamond and glassy carbon

In order to study the allotropic effect on a stopping cross section of carbon, the difference in stopping cross section factors [epsilon] between polycrystalline diamond and glassy carbon (GC) has been estimated for He-4 ions at the incident energies of 1.4-4.0 MeV by backscattering spectrometry. Thin Ag films (similar to 90 nm) were deposited onto the carbon targets to monitor the backscattering yields of Ag during the measurements. The relative stopping cross section factors [epsilon](GC)/[epsilon](diamond) can be determined from the backscattering C yields normalized by the Ag yields. The stopping cross section factors of glassy carbon [epsilon](GC) are found to be higher by 4-5% than those of polycrystalline diamond [epsilon](diamond) for all incident energies examined. (c) 2006 Elsevier B.V. All rights reserved

Characterization of functional materials for liquid blanket systems by cathodoluminescence measurement

Applicability of cathodouminescence (CL) measurements in development of functional materials for advanced liquid blanket systems was investigated by using a conventional scanning microprobe and CCD spectrometer. Firstly, CL spectra of lithium compounds for tritium fuel breeding, oxide, nitride and carbide functional materials for advanced blanket systems, fluoride materials for coolants, etc. were obtained to construct a database. Relations between changes in the spectra and the crystallinities of specimens were examined for ZrO2, Y2O3 and TiO2 coatings baked at different temperatures. The specimens with lower crystallinities showed broader luminescence peak at longer wavelengths. Changes in CL spectra by irradiation damages were also examined for Y2O3 and SiC by ion beam irradiations. Since luminescence intensity decreased significantly for the specimens with low crystallinities, an SEM system which can control the electron beam current more than 2 orders while keeping the spatial resolution of <1 μm is suitable for quick acquisition of CL spectra in the development of the functional materials. Once a database of CL spectra for candidate materials and their changes by crystallinities and irradiation damages is constructed, the CL measurement would be a reliable tool also in inspection and monitoring of materials during reactor construction and operation

Sensitive in-operando observation of Li and O transport in thin-film Li-ion batteries

Thin-film batteries often contain oxides in the anode, cathode, and electrolyte materials. In-operando methods capable of Li and O depth profiling are relevant for battery research to study, e.g. diffusion and trapping of constituents. Here, we demonstrate ion beam-based analytical methods with high depth resolution and sensitivity for depth profiling Li and O in thin-film batteries using 10 MeV Li and He ions. Simultaneous depth profiling of Li and O was performed using combined coincidence elastic recoil detection analysis and Rutherford backscattering spectrometry measurements in the battery with 8 MeV He ions, and the Li and O transport was measured in operando. Reversible Li transport was observed from the LMO anode to the NbO cathode on charging and vice versa during discharging. O transport was observed from the LMO anode to the NbO cathode on first charging with 3.5 V but was not observed on further charging and discharging of the battery. Our in-operando measurements allow direct and quantitative observation of Li and O transport during charge-discharge cycles for thin-film batteries.

Assessing the potential of ion beam analytical techniques for depth profiling Li in thin film Li ion batteries

Depth resolution and probing depth for Li in lithium thin film batteries achievable using different ion beam analytical techniques were investigated. Experiments using protons for nuclear reaction analysis, He ions for time-of-flight (TOF) energy elastic recoil detection analysis (ERDA) in transmission geometry, as well as He and Li ions for coincidence ERDA in transmission geometry are performed. Experimental results are compared in terms of the obtained Li concentration in the separator layer. In coincidence ERDA experiments, significant loss of Li-Li and He-Li coincidence counts was observed due to multiple scattering of recoiled/scattered particles in the battery sample. The ideal achievable Li depth resolution was calculated for the ion beam techniques. A depth resolution of 750, 1030, 310, and 510 x 10(15) atoms/cm(2) could be achieved in the Nb2O5 cathode by nuclear reaction analysis (NRA) using 2 MeV H, TOF-ERDA using 8 MeV He, and coincidence ERDA using 8 MeV He and 8 MeV Li ions, respectively, upon optimization of the experimental setup. While a depth resolution of 120 x 10(15) ions/cm(2) could be achieved for Li by conventional TOF-ERDA using an solid-state detector energy detector and light primary ions such as O under gracing incidence, TOF-ERDA experiments are found to produce significantly higher beam damage in batteries than other techniques. The beam damage in NRA and coincidence ERDA as performed in this study is estimated to be of the order of 10(-4) dpa. (C)&amp; nbsp;2021 Author(s).&amp; nbsp; All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(http://creativecommons.org/licenses/by/4.0/)