Article
Chemistry, Physical
Ji Ma, Baoqi Duan, Yangzhan Xu, Jiye An, Youjie Qiu, Yujia Zhang, Chunting Liu
Summary: Surface modification of electrode materials can improve their electrochemical performance. In this study, the effect of surface amorphization or distortion on potassium storage behavior was investigated. By adjusting the thickness of the amorphous layer, the potassium storage mechanism could be transformed from a diffusion-controlled type to a hybrid capacitive and diffusive type, resulting in improved potassium storage performance.
APPLIED SURFACE SCIENCE
(2023)
Article
Physics, Applied
R. M. Flanagan, M. A. Meyers, S. J. Fensin
Summary: This study systematically investigates the effect of size and concentration of He bubbles in Cu on ejecta production using molecular dynamics simulations. The presence of defects leads to non-planarities in the shock wave itself, resulting in the formation of ejecta as the front reaches the flat free surface.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Energy & Fuels
Kareem Ramzy Aboayanah, Afeez K. Popoola, Aly Abdelaziz, Lei Sun, Ekaterina Ossetchkina, Karl Peterson, Giovanni Grasselli
Summary: This paper investigates the impact of pre-existing cracks on thermal cracking processes in granitic rocks using a novel thermo-mechanical grain-based finite discrete element method. The results show that thermal cracks tend to initiate from the tips of pre-existing cracks due to stress concentration, and the number of initiated thermal cracks decreases with increasing pre-existing crack density. Interestingly, increasing the friction coefficient of pre-existing cracks leads to an increase in the number of thermal cracks under different confinement conditions.
GEOMECHANICS AND GEOPHYSICS FOR GEO-ENERGY AND GEO-RESOURCES
(2022)
Article
Psychiatry
Katie J. S. Lewis, Catrin Lewis, Alice Roberts, Natalie A. Richards, Claudia Evison, Holly A. Pearce, Keith Lloyd, Alan Meudell, Bethan M. Edwards, Catherine A. Robinson, Rob Poole, Ann John, Jonathan Bisson, Ian Jones
Summary: This study aimed to identify the impact of the COVID-19 pandemic on the mental health of individuals with pre-existing mental illness. The results showed that younger age, difficulty accessing mental health services, low income, income affected by COVID-19, worry about COVID-19, reduced sleep, and increased alcohol/drug use were associated with worse mental health outcomes. On the other hand, feeling socially supported by friends/family/services was associated with better mental health. Additionally, individuals with a history of anxiety, depression, post-traumatic stress disorder, or eating disorder were more likely to experience worsening mental health during the pandemic.
Article
Materials Science, Multidisciplinary
Z. Wang, O. Muransky, H. Zhu, T. Wei, Z. Zhang, M. Ionescu, C. Yang, J. Davis, G. Hu, P. Munroe, W. Windes
Summary: The ion irradiation-induced microstructural changes in a carbon-fibre reinforced carbon-matrix (C/C) composite were investigated using Raman spectroscopy. It was found that the high concentration of pre-existing crystal lattice defects in the C/C composite had a significant impact on the disordering of the crystal lattice. In contrast, graphite with fewer pre-existing defects behaved in a more predictable manner. The results suggest the importance of eliminating crystal lattice defects in the as-manufactured microstructure of C/C composites for radiation-tolerant applications. Additionally, the study identified a knowledge gap regarding the electronic energy loss effect on ion irradiation damage in carbon-based materials at intermediate ion energies.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Engineering, Mechanical
Zhonghuai Wu, Liangchi Zhang, Shengyao Yang
Summary: This study used molecular dynamics simulations to investigate the influence of grain position patterns on the deformation of 6H-SiC. It was found that the plastic deformation of 6H-SiC is characterized by a thin amorphous layer at the surface and dislocations in the subsurface, with details varying depending on grain position patterns and gaps.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Physics, Applied
Razvan Burcea, Hugo Bouteiller, Simon Hurand, Per Eklund, Jean-Francois Barbot, Arnaud le Febvrier
Summary: Noble-gas implantation was used to introduce defects in n-type degenerate ScN thin films to tailor their transport properties. The electrical resistivity increased significantly with the damage levels created, while the electron mobility decreased regardless of the nature of the ion implanted and their doses. However, the transport property characterizations showed that two types of defects were formed during implantation, named point-like and complex-like defects depending on their temperature stability.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Abbas Waseem, Mesfin Seid Ibrahim, Chang Lu, Muhammed Waseem, Hiu Hung Lee, K. H. Loo
Summary: This study investigates the issue of pre-existing voids in Power-MOSFET device solder connections and finds that their positions, sizes, and patterns have a significant impact on solder life, providing a basis for establishing solder void inspection standards.
MATERIALS & DESIGN
(2023)
Article
Physics, Applied
M. Matys, B. Adamowicz, T. Kachi, T. Hashizume
Summary: In this study, it is shown that the thermal quenching of defect-related photoluminescence in GaN is not only dependent on defect parameters, but also strongly affected by carrier drift and diffusion in the depletion region. The findings indicate that the slope of PL thermal quenching and the starting temperature of quenching are significantly influenced by these processes. The results suggest that caution should be taken when interpreting the activation energy values of defects, especially in cases of high surface state density due to the impact of drift-diffusion processes.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Meteorology & Atmospheric Sciences
Paolo Ramoni-Perazzi, Marcelo Passamani, Dirk Thielen, Carlos Padovani, Marco Aurelio Arizapana-Almonacid
Summary: This study evaluated and improved bioclimatic databases by analyzing precipitation and temperature surfaces in Brazil, allowing for more accurate species distribution predictions and providing a realistic image of species' ecological needs. The developed BrazilClim database can be replicated in other regions to achieve similar results.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2022)
Article
Oncology
Yen-Chang Chen, Wan-Ming Chen, Ming-Feng Chiang, Ben-Chang Shia, Szu-Yuan Wu
Summary: This study investigates the effects of pre-existing sleep disorders on the survival outcomes of women receiving standard treatments for breast invasive ductal carcinoma (IDC). The study found that women with pre-existing sleep disorders had poorer survival outcomes. Therefore, screening and evaluating for sleep disorders prior to breast surgery is important for predicting survival in breast cancer patients. Future research can explore the survival benefits of pharmacological and behavioral treatments for sleep problems in patients with breast cancer.
Article
Chemistry, Physical
Hongqin Lei, Jian Cheng, Dinghuai Yang, Linjie Zhao, Mingjun Chen, Jinghe Wang, Qi Liu, Wenyu Ding, Guang Chen
Summary: When repairing and removing laser damage points on KDP crystal surfaces, various forms of micro-defects can affect the repair quality, which can be addressed by simulating the ball-end milling repair process.
Article
Engineering, Electrical & Electronic
Sujan Sarkar, Ramdas P. Khade, Amitava DasGupta, Nandita DasGupta
Summary: The effect of the GaN cap layer on the performance of AlInN/GaN-based HEMTs has been studied. The addition of the GaN cap layer reduces gate leakage current, increases saturation drain current, improves subthreshold swing, and enhances the I-ON/I-OFF ratio of HEMTs. It also reduces the current collapse due to gate-lag and drain-lag and improves breakdown voltage.
MICROELECTRONIC ENGINEERING
(2022)
Article
Energy & Fuels
Haiyang Wang, Miaomiao Liang, Hao Ma, Huimin Zhang, Zhun Guo, Yang Zhao, Yuzhen Zhao, Najeeb Ur RehmanLashari, Zongcheng Miao
Summary: Interfacial engineering through surface amorphization is an effective strategy to control the structure and properties of materials. In this study, a facile hydrothermal method followed by NaBH4 treatment is used to fabricate surface-amorphized Co3S4 (SA-Co3S4). Characterization techniques such as XRD and SEM reveal the micro flower structure of Co3S4, while TEM analysis demonstrates the heterointerface between the crystal core of Co3S4 and the defect-rich amorphous surface, leading to enhanced electrical conductivity. Electrochemical measurements show that SA-Co3S4 exhibits high specific capacitance of 1043.9 F g-1 at 0.5 A g-1 and good rate performance. When used as a cathode in an asymmetric supercapacitor, SA-Co3S4, combined with active carbon as an anode, achieves a high energy density of 41.9 Wh kg-1 at a power density of 162 W kg-1 and excellent cycling durability with over 90% retention rate after 10,000 cycles. This work offers a novel structure design strategy for cobalt sulfide materials with superior conductivity and electrochemical performances.
JOURNAL OF ENERGY STORAGE
(2023)
Article
Construction & Building Technology
Hussein Nasser, Lucie Vandewalle, Els Verstrynge
Summary: The study revealed that transverse cracks cause localized section loss, leading to nonlinearity in the relation between longitudinal crack widths and section loss. Additionally, it was found that longitudinal corrosion cracks reduce the number of flexural cracks, while transverse cracks create weak points that trigger beam failure. Furthermore, transverse corrosion cracks may lead to misaligned minimum cross-sections on the tensile rebars, affecting the failure mechanism.
CONSTRUCTION AND BUILDING MATERIALS
(2022)
Article
Physics, Multidisciplinary
Alexander Azarov, Calliope Bazioti, Vishnukanthan Venkatachalapathy, Ponniah Vajeeston, Edouard Monakhov, Andrej Kuznetsov
Summary: In this study, the phenomenon of polymorphism in gallium oxide is investigated. It is found that the amorphization can be significantly suppressed by the phase transition, leading to the fabrication of a highly oriented single-phase film. A novel mode of lateral polymorphic regrowth, not previously observed in solids, is also discovered. These findings open up new directions for research on polymorphs in Ga2O3 and potentially in other materials.
PHYSICAL REVIEW LETTERS
(2022)
Article
Physics, Applied
S. B. Kjeldby, A. Azarov, P. D. Nguyen, V. Venkatachalapathy, R. Miksova, A. Mackova, A. Kuznetsov, O. Prytz, L. Vines
Summary: Defect accumulation and annealing phenomena in Si-implanted monoclinic gallium oxide wafers were studied using RBS/c, XRD, and (S)TEM. The accumulation of radiation disorder was found to be accompanied by strain accumulation, resulting in crystalline-to-crystalline phase transitions. Annealing of selected samples showed complex structural transformations, which were influenced by the fluence and temperature.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Mechanical
M. Nowak, K. Mulewska, A. Azarov, L. Kurpaska, A. Ustrzycka
Summary: This study presents a novel peridynamic constitutive relations for predicting plastic deformation and damage evolution in irradiated materials. The plastic behavior of the material, where radiation induced defects contribute to peridynamic porosity, is described by the Gurson-Tvergaard-Needleman (GTN) yield criterion with irradiation hardening. The physical relevance of coupling the porosity with the nonlinear irradiation hardening is discussed, and the expressions for the yield function, kinetics of porosity evolution, irradiation hardening, and plastic flow rule are derived.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2023)
Article
Chemistry, Physical
A. Mackova, A. Jagerova, O. Lalik, R. Miksova, D. Poustka, J. Mistrik, V Holy, J. D. Schutter, U. Kentsch, P. Marvan, A. Azarov, A. Galeckas
Summary: ZnO nanopillars were implanted with Au-400 keV and Ag-252 keV ions at different fluences. The presence of Ag and Au in the ZnO nanopillar layers was confirmed by Rutherford Back-Scattering spectrometry (RBS), which matched well with theoretical calculations. Ion implantation resulted in a reduction in the thickness of the ZnO nanopillar layer. Spectroscopic Ellipsometry (SE) showed a decrease in refractive index in the nanopillar parts with embedded Au and Ag ions. XRD revealed a decrease in vertical domain size due to radiation damage from Au ions. Optical activity in the nanopillars was observed using SE and diffuse reflectance spectroscopy (DRS) in the presence of Au and Ag nanoparticles. PL features linked to ZnO deep level emission were enhanced due to plasmonic interaction with metal nanoparticles created by Ag and Au implantation. Photocatalytic activity was more influenced by the nanoparticles in the layer rather than surface morphology. Dual implantation with Ag and Au ions resulted in enhanced optical activity without significant morphology deterioration compared to solely Au-ion implanted nanopillars.
APPLIED SURFACE SCIENCE
(2023)
Article
Physics, Applied
Alexander Azarov, Augustinas Galeckas, Francis Chi-Chung Ling, Andrej Kuznetsov
Summary: Ion implantation is an effective method for introducing defects into semiconductors. In this study, we investigated the use of crystallographically aligned implants to control the balance between optically active defects in ZnO. Optical data and structural analysis confirmed the formation of different dominant crystalline defects in samples implanted along and off the [0001] direction. The proportions of extended and point defects in the initial as-implanted states of these samples were found to significantly influence the defect-related luminescence upon annealing. We conclude that channeling implants have value in functionalizing defects in semiconductors by tuning specific spectral contents in defect-related emission bands.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Instruments & Instrumentation
T. A. O. Jafer, T. T. Thabethe, O. S. Odutemowo, S. A. Adeojo, H. A. A. Abdelbagi, J. B. Malherbe
Summary: Glassy carbon samples were implanted with ruthenium ions and investigated using XRD, Raman spectroscopy, AFM, and SIMS to study the microstructural changes and diffusion behavior of ruthenium. The results showed that ion implantation caused amorphization and increased tensile stress in the implanted region. Annealing led to recrystallization and a change from tensile to compressive stress. SIMS results indicated the aggregation and segregation of ruthenium atoms at different temperatures, which affected the surface roughness observed by AFM.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Physics, Applied
Alexander Azarov, Ji-Hyeon Park, Dae-Woo Jeon, Andrej Kuznetsov
Summary: The migration properties of intrinsic defects in alpha-Ga2O3 were investigated by introducing lattice disorder through ion irradiation and monitoring its evolution with respect to ion dose, flux, and temperature. The results showed a significantly high mobility of intrinsic defects in alpha-Ga2O3, as evidenced by the presence of two distinct disordered regions near the surface and in the bulk, instead of the expected Gaussian shape. Furthermore, the accumulation of disorder was found to be highly sensitive to ion flux and temperature, indicating a dose-rate effect.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
A. Y. Polyakov, A. I. Kochkova, A. Azarov, V. Venkatachalapathy, A. V. Miakonkikh, A. A. Vasilev, A. V. Chernykh, I. V. Shchemerov, A. A. Romanov, A. Kuznetsov, S. J. Pearton
Summary: Ion beam fabrication of metastable polymorphs of Ga2O3, assisted by the controllable accumulation of the disorder in the lattice, is explored for its alternative approach to conventional deposition techniques. In this study, two strategies - ion implantation of silicon donors and plasma treatment with hydrogen - are investigated for tuning the electron concentration in the ion beam created metastable kappa-polymorph. The results show that silicon doping did not change the high resistive state, while hydrogen plasma treatment converted the ion beam fabricated kappa-polymorph to n-type conductivity.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
A. Y. Polyakov, A. Kuznetsov, A. Azarov, A. V. Miakonkikh, A. V. Chernykh, A. A. Vasilev, I. V. Shchemerov, A. I. Kochkova, N. R. Matros, S. J. Pearton
Summary: Defects in lightly Sn-doped (2 x 10(16) cm(-3)) (010)-oriented bulk beta-Ga2O3 before and after Au ion implantation and hydrogen plasma treatment were studied. Au implantation introduced defects that depleted carriers and created electron traps and deep acceptors with energy levels similar to deep traps in beta-Ga2O3. Hydrogen plasma treatment enhanced the photocurrent and photo-capacitance and reduced the width of the insulating layer. The results can be explained by hydrogen passivation of Ga vacancies, which returned the region to n-type conductivity.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2023)
Article
Materials Science, Coatings & Films
Alexander Azarov, Vishnukanthan Venkatachalapathy, In-Hwan Lee, Andrej Kuznetsov
Summary: Gallium oxide (Ga2O3) shows complex behavior under ion irradiation, with both functional properties and polymorphic transformations affected by ion-induced disorder. Minimizing lattice disorder can be achieved through postirradiation anneals or through implants at elevated temperatures to prevent disorder accumulation. In this study, both approaches were used to minimize radiation disorder in monoclinic beta-Ga2O3, with implants at 300℃ effectively suppressing defect formation while postirradiation anneals above 900℃ were necessary to achieve similar crystalline quality in samples implanted at room temperature.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Multidisciplinary
H. Arslan, I. Aulika, A. Sarakovskis, L. Bikse, M. Zubkins, A. Azarov, J. Gabrusenoks, J. Purans
Summary: An investigation was conducted on the spectroscopic and structural characterization of semiconducting yttrium oxide thin film deposited at 623 K (+/- 5K) using reactive pulsed direct current magnetron sputtering. The results indicate the formation of yttrium monoxide (YO) in the transition region between beta-Y2O3 and alpha-Y2O3, accompanied by crystalline Y2O3. The stability of monoxide is limited by the crystal size, leading to distortion in the crystal structure and the arrangement in nano-crystalline/amorphous phase.
Article
Materials Science, Multidisciplinary
E. Wyszkowska, C. Mieszczynski, L. Kurpaska, A. Azarov, W. Chrominski, I Jozwik, A. Esfandiarpour, A. Kosinska, D. Kalita, R. Diduszko, J. Jagielski, S. T. Nori, M. Alava
Summary: The radiation resistance of NixFe1-x single crystals was studied by irradiating them with Ni-58 ions and analyzing the resulting damage. It was found that the addition of iron reduced the formation of damage and increased the hardness of the alloy. Simulations showed that the presence of FeNi3 (L1(2)) phase contributed to the high hardness of the Ni0.62Fe0.38 alloy.
JOURNAL OF NUCLEAR MATERIALS
(2023)
Article
Instruments & Instrumentation
Cyprian Mieszczynski, Przemyslaw Jozwik, Kazimierz Skrobas, Kamila Stefanska-Skrobas, Renata Ratajczak, Jacek Jagielski, Frederico Garrido, Edyta Wyszkowska, Alexander Azarov, Katharina Lorenz, Eduardo Alves
Summary: In this work, the unique capability of the new version of the McChasy code (called McChasy2) to simulate experimental energy spectra delivered by Rutherford Backscattering Spectrometry in channeling direction (RBS/C) using large atomic structures (ca. 108 atoms) is presented. The focus is on the simulations of extended structural defects (edge dislocations and loops) formed inside nickel-based single-crystal alloys, which are widely studied and promising materials for high-temperature applications.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS
(2023)
Article
Multidisciplinary Sciences
Alexander Azarov, Javier Garcia Fernandez, Junlei Zhao, Flyura Djurabekova, Huan He, Ru He, Oystein Prytz, Lasse Vines, Umutcan Bektas, Paul Chekhonin, Nico Klingner, Gregor Hlawacek, Andrej Kuznetsov
Summary: The γ/β double polymorph Ga2O3 structures demonstrate exceptionally high radiation tolerance, tolerating disorder equivalent to hundreds of displacements per atom. This discovery highlights a new class of radiation tolerant semiconductors.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
E. Wyszkowska, C. Mieszczynski, L. Kurpaska, A. Azarov, I. Jozwik, A. Kosinska, W. Chrominski, R. Diduszko, W. Y. Huo, I. Cieslik, J. Jagielski
Summary: Radiation-induced heterogeneous damage is the main cause of failures in nuclear power reactors, but single crystal materials without grain boundaries show promise in overcoming this issue. By fine-tuning the composition, heterogeneous damage in NixFe1-x single crystal alloys can be further overcome.
