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transitionsYang, Q.*; Yang, X.*; Wang, Y.*; Fei, Y.*; Li, F.*; Zheng, H.*; Li, K.*; Han, Y.*; Hattori, Takanori; Zhu, P.*; et al.
Nature Communications (Internet), 15, p.7778_1 - 7778_9, 2024/09
Times Cited Count：0 Percentile：0.00(Multidisciplinary Sciences)Luminescent materials that simultaneously embody bright singlet and triplet excitons hold great potential in optoelectronics, signage, and information encryption. However, achieving high-performance white-light emission is severely hampered by their inherent unbalanced contribution of fluorescence and phosphorescence. Herein, we address this challenge by pressure treatment engineering via hydrogen bonding cooperativity effect to realize the mixture of n-- transitions, where the triplet state emission was boosted from 7% to 40% in isophthalic acid (IPA). A superior white-light emission based on hybrid fluorescence and phosphorescence was harvested in pressure-treated IPA, and the photoluminescence quantum yield was increased to 75% from the initial 19% (blue-light emission). In-situ high-pressure IR spectra, X ray diffraction, and neutron diffraction reveal continuous strengthening of the hydrogen bonds with the increase of pressure. Furthermore, this enhanced hydrogen bond is retained down to the ambient conditions after pressure treatment, awarding the targeted IPA efficient intersystem crossing for balanced singlet/triplet excitons population and resulting in efficient white-light emission. This work not only proposes a route for brightening triplet states in organic small molecule, but also regulates the ratio of singlet and triplet excitons to construct high-performance white-light emission.
Zhu, L.*; He, H.*; Naeem, M.*; Sun, X.*; Qi, J.*; Liu, P.*; Harjo, S.; Nakajima, Kenji; Li, B.*; Wang, X.-L.*
Physical Review Letters, 133(12), p.126701_1 - 126701_6, 2024/09
Zhang, Z.*; Hattori, Takanori; Song, R.*; Yu, D.*; Mole, R.*; Chen, J.*; He, L.*; Zhang, Z.*; Li, B.*
Journal of Applied Physics, 136(3), p.035105_1 - 035105_8, 2024/07
Times Cited Count：1 Percentile：0.00(Physics, Applied)Solid-state refrigeration using barocaloric materials is environmentally friendly and highly efficient, making it a subject of global interest over the past decade. Here, we report giant barocaloric effects in sodium hexafluorophosphate (NaPF
) and sodium hexafluoroarsenate (NaAsF) that both undergo a cubic-to-rhombohedral phase transition near room temperature. We have determined that the low-temperature phase structure of NaPF is a rhombohedral structure with space group R
and NaAsF, i.e., F
, E
, and A
. The phase transition temperature varies with pressure at a rate of dT
/dP = 250 and 310 K/GPa for NaPF and NaAsF. The pressure-induced entropy changes of NaPF and NaAsF are determined to be around 45.2 and 35.6J kg
K, respectively. The saturation driving pressure is about 40 MPa. The pressure-dependent neutron powder diffraction suggests that the barocaloric effects are related to the pressure-induced cubic-to-rhombohedral phase transitions.
Choi, B.; Nishida, Akemi; Kawata, Manabu; Shiomi, Tadahiko; Li, Y.
JAEA-Research 2024-001, 206 Pages, 2024/03
JAEA-Research-2024-001.pdf:9.12MB
In the assessment of seismic safety and the design of building structures in nuclear facilities, lumped mass models have been used as standard methods. Recent advances in computer capabilities allow the use of three-dimensional finite element (3D FE) models to account for the 3D behavior of buildings, material nonlinearity, and the nonlinear soil-structure interaction effect. While 3D analysis method has many advantages, it is necessary to ensure its reliability as a new approach. The International Atomic Energy Agency performed an international benchmark study using the 3D FE analysis model for reactor building of Unit 7 at TEPCO's Kashiwazaki-Kariwa Nuclear Power Station based on recordings from the Niigataken Chuetsu-oki Earthquake in 2007. Multiple organizations from different countries participated in this study and the variation in their analytical results was significant, indicating an urgent need to improve the reliability of the analytical results by standardization of the analytical methods using 3D FE models. Additionally, it has been pointed out that it is necessary to understand the 3D behavior in the seismic fragility assessment of buildings and equipment, using realistic seismic response analysis method based on 3D FE models. In view of these considerations, a guideline for the seismic response analysis method using a 3D FE model was developed by incorporating the latest knowledge and findings in this area. The purpose of the guideline is to improve the reliability of the seismic response analysis method using 3D FE model of reactor buildings. The guideline consists of a main body, commentaries, and appendixes. The standard procedures, recommendations, key points to note, and technological bases for conducting seismic response analysis on reactor buildings using 3D FE models are provided in the guideline. In addition, the guideline will be revised reflecting the latest knowledge.
Li, X.*; Zhu, R.*; Xin, J.*; Luo, M.*; Shang, S.-L.*; Liu, Z.-K.*; Yin, C.*; Funakoshi, Kenichi*; Dippenaar, R. J.*; Higo, Yuji*; et al.
CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 84, p.102641_1 - 102641_6, 2024/03
Times Cited Count：0 Percentile：0.00(Thermodynamics)
-Ti alloyZhang, B.*; Xin, S.*; Huang, M.*; Mao, W.; Jia, W.*; Li, Q.*; Li, S.*; Zhang, S.*; Mao, C.*
Materials Science & Engineering A, 890, p.145898_1 - 145898_7, 2024/01
Times Cited Count：0 Percentile：0.00(Nanoscience & Nanotechnology)A significant increase in the recovery strain of a high-Zr -Ti alloy from 2.25 % to 5.5 % when decreasing the deformation temperature from 300 K to 77 K is reported in this study. It is found that the super-elasticity of this alloy is independent of the -grain size at 77 K. The results reveal that a coarse-grained specimen exhibited approximately the same super-elasticity as its ultra-fine grain counterpart at 77 K. The relative easiness of deformation-induced martensitic transformation and dislocation slip was substantially changed at 77 K, with a strong suppression of dislocation slip, which overshadowed the effect of grain refinement on the super-elasticity.
Lloveras, P.*; Zhang, Z.*; Zeng, M.*; Barrio, M.*; Kawakita, Yukinobu; Yu, D.*; Lin, S.*; Li, K.*; Moya, X.*; Tamarit, J.-L.*; et al.
Barocaloric Effects in the Solid State; Materials and methods, p.7_1 - 7_30, 2023/10
Times Cited Count：232 Percentile：99.37(Multidisciplinary Sciences)As Chapter 1 of the ebook entitled as "Barocaloric Effects in the Solid State", various plastic crystals (PC) showing colossal barocaloric (BC) effect are introduced. A method to determine the BC response in PCs, thermodynamic origin of BC effects, spectroscopic insights from quasi-elastic neutron scattering and application of PCs are explained.
Bao, S.*; Gu, Z.-L.*; Shangguan, Y.*; Huang, Z.*; Liao, J.*; Zhao, X.*; Zhang, B.*; Dong, Z.-Y.*; Wang, W.*; Kajimoto, Ryoichi; et al.
Nature Communications (Internet), 14, p.6093_1 - 6093_9, 2023/09
Times Cited Count：12 Percentile：92.78(Multidisciplinary Sciences)Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Li, Y.; Ota, Akira*; Sonobe, Hideaki*; Ino, Susumu*; Ugata, Takeshi*
Mechanical Engineering Journal (Internet), 10(4), p.23-00026_1 - 23-00026_11, 2023/08
In the seismic evaluation of nuclear facility buildings, basemat uplift-the phenomenon during which the bottom of the basemat of a building partially rises from the ground owing to overturning moments during earthquakes-is a very important aspect because it affects not only structural strength and integrity, but also the response of equipment installed in the building. However, there are not enough analytical studies on the behavior of buildings with a low ground contact ratio due to basemat uplift during earthquakes. In this study, we conducted a simulation using a three-dimensional finite element model from past experiments on basemat uplift; further, we confirmed the validity of this approach. In order to confirm the difference in the analytical results depending on the analysis code, the simulation was performed under the same analytical conditions using the three analysis codes, which are E-FrontISTR, FINAS/STAR and TDAPIII, and the obtained analysis results were compared. Accordingly, we investigated the influence of the difference in adhesion on the structural response at low ground contact ratio. In addition, we confirmed the effects of significant analysis parameters on the structural response via sensitivity analysis. In this paper, we report the analytical results and insights obtained from these investigations.
neutron diffraction study on the deformation behavior of the plastic inorganic semiconductor Ag
SWang, Y.*; Gong, W.; Kawasaki, Takuro; Harjo, S.; Zhang, K.*; Zhang, Z. D.*; Li, B.*
Applied Physics Letters, 123(1), p.011903_1 - 011903_6, 2023/07
Times Cited Count：4 Percentile：63.08(Physics, Applied)
X-ray synchrotron diffractionLi, H.*; Liu, Y.*; Zhao, W.*; Liu, B.*; Tominaga, Aki; Shobu, Takahisa; Wei, D.*
International Journal of Plasticity, 165, p.103612_1 - 103612_20, 2023/06
Times Cited Count：11 Percentile：90.11(Engineering, Mechanical)In order to clarify the strength properties of Co-free maraging steel, tensile experiment using high energy synchrotron X-ray diffraction was performed. Diffraction profiles from the martensitic and austenitic phases were obtained, and their strength and width were observed to vary as loading. Analysis of the diffraction profiles showed that the content of martensite in the as-aged material decreased slowly at low stress levels and decreased rapidly at high stress levels. On the other hand, the austenite phase in the as-solution materials was significantly transformed the martensite phase as the stress increased. It was clarified to be responsible for their respective strength properties.
Fe
intermetallic compoundCao, Y.*; Zhou, H.*; Khmelevskyi, S.*; Lin, K.*; Avdeev, M.*; Wang, C.-W.*; Wang, B.*; Hu, F.*; Kato, Kenichi*; Hattori, Takanori; et al.
Chemistry of Materials, 35(8), p.3249 - 3255, 2023/04
Times Cited Count：2 Percentile：32.09(Chemistry, Physical)Hydrostatic and chemical pressure are efficient stimuli to alter the crystal structure and are commonly used for tuning electronic and magnetic properties in materials science. However, chemical pressure is difficult to quantify and a clear correspondence between these two types of pressure is still lacking. Here, we study intermetallic candidates for a permanent magnet with a negative thermal expansion (NTE). Based on in situ synchrotron X-ray diffraction, negative chemical pressure is revealed in HoFe on Al doping and quantitatively evaluated by using temperature and pressure dependence of unit cell volume. A combination of magnetization and neutron diffraction measurements also allowed one to compare the effect of chemical pressure on magnetic ordering with that of hydrostatic pressure. Intriguingly, pressure can be used to control suppression and enhancement of NTE. Electronic structure calculations indicate that pressure affected the top of the majority band with respect to the Fermi level, which has implications for the magnetic stability, which in turn plays a critical role in modulating magnetism and NTE. This work presents a good example of understanding the effect of pressure and utilizing it to control properties of functional materials.
Nakamura, Jumpei*; Kawakita, Yukinobu; Okabe, Hirotaka*; Li, B.*; Shimomura, Koichiro*; Suemasu, Takashi*
Journal of Physics and Chemistry of Solids, 175, p.111199_1 - 111199_8, 2023/04
Times Cited Count：2 Percentile：8.43(Chemistry, Multidisciplinary)Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Shiomi, Tadahiko; Li, Y.
Proceedings of 2023 International Congress on Advanced in Nuclear Power Plants (ICAPP 2023) (Internet), 10 Pages, 2023/04
Our research and development are aimed at improving the accuracy of the three-dimensional seismic evaluation analysis method for nuclear buildings, which contributes to the probabilistic risk assessment caused by earthquakes (seismic PRA), using actual seismic observation records in collaboration with the Nuclear Regulation Authority since 2019. In this study, we constructed a large-scale observation system that enabled simultaneous measurements at multiple positions during earthquakes or against artificial waves. The accelerometers of the observation system were installed on/in the soil, floors, and on the walls of the nuclear building. This paper presents an outline of the large-scale observation system and the findings obtained from the analysis of the seismic observation records acquired using the system.
Jiang, X.*; Hattori, Takanori; Xu, X.*; Li, M.*; Yu, C.*; Yu, D.*; Mole, R.*; Yano, Shinichiro*; Chen, J.*; He, L.*; et al.
Materials Horizons, 10(3), p.977 - 982, 2023/03
Times Cited Count：19 Percentile：93.10(Chemistry, Multidisciplinary)As a promising environment-friendly alternative to current vapor-compression refrigeration, solid-state refrigeration based on the barocaloric effect has been attracting world wide attention. Generally, both phases in which a barocaloric effect occurs are present at ambient pressure. Here, instead, we demonstrate that KPF
exhibits a colossal barocaloric effect due to the creation of a high-pressure rhombohedral phase. The phase diagram is constructed based on pressure-dependent calorimetric, Raman scattering, and neutron diffraction measurements. The present study is expected to provide an alternative routine to colossal barocaloric effects through the creation of a high-pressure phase.
Choi, B.; Nishida, Akemi; Li, Y.; Takada, Tsuyoshi
Earthquake Engineering and Resilience (Internet), 1(4), p.427 - 439, 2022/12
no abstracts in English
Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.
International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12
Times Cited Count：77 Percentile：99.57(Engineering, Mechanical)Hasegawa, Kunio; Strnadel, B.*; Li, Y.; Lacroix, V.*
Journal of Pressure Vessel Technology, 144(6), p.061202_1 - 061202_6, 2022/12
Times Cited Count：1 Percentile：11.11(Engineering, Mechanical)When pipe walls are thin, part-through flaws are easily develop into through-wall flaws, and the likelihood of coolant leakage is high. The ASEM Code Section XI provides final allowable flaw angles of through-wall flaw for thin-wall pipes. The final allowable angles are applied to pipes in order to maintain structural integrity if the part-through flaws become through-wall flaws. To ensure that this stability is compromised, plastic collapse stresses for through-wall flaws are combined with allowable stresses. However, the final allowable angles of through-wall flaws are not identified for thin-walled pipes. This paper compares plastic collapse stresses of through-wall flaws and allowable stresses of part-through flaws for pipes. The comparison of these stresses is used to derive the final allowable angles of through-wall flaws. The angles can be expressed either in the form of exact solutions or as conventional options that are appropriate for various service level conditions.
Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Li, Y.
Proceedings of 29th International Conference on Nuclear Engineering (ICONE 29) (Internet), 6 Pages, 2022/08
In the seismic evaluation of nuclear facility buildings, basemat uplift-the phenomenon during which the bottom of the basemat of a building partially rises from the ground owing to overturning moments during earthquakes-is a very important aspect because it affects not only structural strength and integrity, but also the response of equipment installed in the building. However, there are not enough analytical studies on the behavior of buildings with a low ground contact ratio due to basemat uplift during earthquakes. In this study, we conducted a simulation using a three-dimensional finite element model from past experiments on basemat uplift; further, we confirmed the validity of this approach. In order to confirm the difference in the analytical results depending on the analysis code, the simulation was performed under the same analytical conditions using the three analysis codes, which are E-FrontISTR, FINAS/STAR and TDAPIII, and the obtained analysis results were compared. Accordingly, we investigated the influence of the difference in adhesion on the structural response at low ground contact ratio. In addition, we confirmed the effects of significant analysis parameters on the structural response via sensitivity analysis. In this paper, we report the analytical results and insights obtained from these investigations.
Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Li, Y.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
We have conducted research and development with the aim of improving the accuracy of three-dimensional seismic evaluation analysis method for nuclear buildings that contributes to probabilistic risk assessment caused by earthquakes (seismic PRA). In 2019, we started our research on improving the accuracy and validating the three-dimensional seismic analysis method used for nuclear buildings using actual seismic observation records in collaboration with the Nuclear Regulation Authority. In this research, we constructed a large-scale observation system that enabled simultaneous observation at multiple positions during natural earthquakes or artificial waves by installing accelerometers not only on/in the soil and on the floors of the building but also on the walls of the building, targeting the High Temperature engineering Test Reactor, which is one of nuclear facilities of JAEA. In this paper, we report the outline of the large-scale observation system and the knowledge obtained from the analysis results of the seismic observation records acquired using this system.
