Article
Materials Science, Multidisciplinary
Daniel Bennett, Pablo Aguado-Puente, Emilio Artacho, Nicholas C. Bristowe
Summary: This paper extends the phenomenological theory of polar instability to include the coupling to perovskite tilts. The Landau theory for homogeneous tilts is first explored, setting the stage for the Landau-Ginzburg theory which describes varying tilt amplitudes across a thin film. The theory is also generalized to account for the response to an applied electric field normal to the interface, allowing for a finer control on phase transitions.
Article
Materials Science, Multidisciplinary
Buhao Zhang, Youwei Wang, Jie Yin, Yichen Wang, Hangfeng Zhang, Tamas Csanadi, Jan Dusza, Michael J. Reece, Nan Lin, Xiao Yang, Xuejian Liu, Zhengren Huang, Dongliang Jiang
Summary: High-hardness rock-salt structured transitional metal carbides (TMC) are of interest as potential thermal protection materials. However, their brittleness limits their performance in harsh environments. This study proposes a strategy to introduce plasticity in TaC-HfC solid solutions by adjusting carbon deficiency. Experimental results confirm the presence of plasticity and high nanohardness in the Ta0.8Hf0.2C0.8 composition.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Multidisciplinary
Yiqing Zhang, Yingzhu Zhang, Benfang Niu, Yanchun Huang, Haotian Wu, Weifei Fu, Hongzheng Chen
Summary: 2D/3D/2D-structured perovskite films are constructed by depositing phenethylammonium bromide (PEABr) on top and 2D perovskite PEA2FA2Pb3Br10 at the bottom of 3D perovskite. Finally, a power conversion efficiency of 24.2% is achieved, and the encapsulated device maintains 93.5% of its initial efficiency under 1 sun equivalent illumination of 1000 h in air with a humidity of 50 ± 5%.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Multidisciplinary
Marius Adrian Husanu, Dana Georgeta Popescu, Federico Bisti, Luminita Mirela Hrib, Lucian Dragos Filip, Iuliana Pasuk, Raluca Negrea, Marian Cosmin Istrate, Leonid Lev, Thorsten Schmitt, Lucian Pintilie, Andrey Mishchenko, Cristian Mihail Teodorescu, Vladimir N. Strocov
Summary: A deeper understanding of the coupling at the interface of multiferroics heterostructures has been achieved through the use of synchrotron radiation techniques. The authors used k-resolved soft X-ray photoemission spectroscopy and first principles calculations to investigate the band structure of several multiferroic heterostructures, identifying the distinct signature of the interface. The experimental results revealed the influence of ferroelectric polarization on charge density, electron-lattice interaction, and mobility of charge carriers in these systems.
COMMUNICATIONS PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Pierfrancesco Maltoni, Gianni Barucca, Bogdan Rutkowski, Maria Chiara Spadaro, Petra E. Jonsson, Gaspare Varvaro, Nader Yaacoub, Jose A. De Toro, Davide Peddis, Roland Mathieu
Summary: The magnetic coupling of SrFe12O19/CoFe2O4 nanocomposites is investigated. The structural coherence and texture at the interfaces of the nanostructures are evidenced by advanced electron microscopy. The exchange intergranular interaction is evidenced and the critical thickness for uniform reversal of coupled interfaces is quantified.
Article
Materials Science, Multidisciplinary
Junyu Huang, Chang Liu, Yifan Cui, Yuxiang Ling, Keming Chen, Kunlong Zhao, Xiangshang Xiao, Bin Yuan, Amitesh Paul
Summary: Helical or non-collinear structures in rare-earth can be the basis of all-spin-based technology. The exchange coupling between antiferromagnet and rare-earth was explored in this study. A frustrated inter-domain magnetic interaction was observed at the exchange-coupled interfaces, leading to a coexistence of spin-freezing like ordering. However, due to the small number of irreversible spins within the rare-earth, the interfacial coupling remained weak, resulting in minimal exchange bias field.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Tianhao Wu, Luis K. Ono, Rengo Yoshioka, Chenfeng Ding, Congyang Zhang, Silvia Mariotti, Jiahao Zhang, Kirill Mitrofanov, Xiao Liu, Hiroshi Segawa, Ryota Kabe, Liyuan Han, Yabing Qi
Summary: Nickel oxide (NiOx) is a promising hole-selective contact for efficient perovskite solar cells (PSCs), but its long-term operational lifetime is limited by light-induced degradation. This study clarifies the degradation mechanism and proposes a solution by constructing a TMSBr buffer layer, resulting in significantly improved operational lifetimes for NiOx-based PSCs.
ENERGY & ENVIRONMENTAL SCIENCE
(2022)
Article
Chemistry, Physical
Jianxing Xia, Ruiling Zhang, Junsheng Luo, Hua Yang, Hongyu Shu, Haseeb Ashraf Malik, Zhongquan Wan, Yu Shi, Keli Han, Ruilin Wang, Xiaojun Yao, Chunyang Jia
Summary: PHC as an efficient and stable single dopant in PSCs demonstrates advantages in hydrophobicity and larger van der Waals radius, leading to improved stability and enhanced efficiency through conversion of deep trap states, interface optimization, and carrier transfer enhancement.
Article
Multidisciplinary Sciences
Qin Tan, Zhaoning Li, Guangfu Luo, Xusheng Zhang, Bo Che, Guocong Chen, Han Gao, Dong He, Guoqiang Ma, Jiafeng Wang, Jingwei Xiu, Huqiang Yi, Tao Chen, Zhubing He
Summary: A dimethylacridine-based molecular doping process is used to create a well-matched p-perovskite/ITO contact and achieve all-round passivation of grain boundaries, resulting in a certified power conversion efficiency of 25.39%.
Article
Optics
Kai Yao, Siqi Li, Zhiliang Liu, Yiran Ying, Petr Dvorak, Linfeng Fei, Tomas Sikola, Haitao Huang, Peter Nordlander, Alex K-Y Jen, Dangyuan Lei
Summary: This study investigates the influence of plasmonic resonance on carrier dynamics in perovskite solar cells by incorporating specially designed poly(3-aminothiophenol)-coated gold nanoparticles into the perovskite absorber. Through changes in the photophysical properties of the OIHP films, transient absorption spectroscopy, and density functional theory calculations, the research shows that plasmon excitation can fill trap sites at the grain boundary region and improve the device performance. The work provides clear evidence for plasmon-induced trap occupation in OIHP, suggesting that plasmonic nanostructures may be effective additives to enhance the efficiency of perovskite solar cells and thin-film solar cells in general.
LIGHT-SCIENCE & APPLICATIONS
(2021)
Article
Physics, Applied
Takeyoshi Onuma, Kanta Kudo, Mizuki Ono, Wataru Kosaka, Kohei Shima, Kyohei Ishii, Kentaro Kaneko, Yuichi Ota, Tomohiro Yamaguchi, Kazunobu Kojima, Shizuo Fujita, Shigefusa F. Chichibu, Tohru Honda
Summary: Temperature-dependent cathodoluminescence spectra were measured for rock salt-structured MgxZn1-xO films. The Mg0.95Zn0.05O film exhibited the shortest deep UV peak wavelength. Relatively high equivalent internal quantum efficiencies were obtained. The Tauc plots, obtained from temperature-dependent optical transmittance measurements, exhibited large Stokes-like shifts. Time-resolved photoluminescence (PL) signals at 7 K exhibited fast and slow decay components.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Geological
Cheng Lyu, Jianfeng Liu, Yi Ren, Chao Liang, Yin Zeng
Summary: This study conducted tests on impure salt rocks in China under thermal-hydro-mechanical coupling condition and found that the mechanical characteristics and gas tightness of the salt rock vary with confining pressure and temperature. The study also established empirical formulas and models to describe the permeability evolution of salt rock, which is important for the safety evaluation of salt caverns.
ENGINEERING GEOLOGY
(2022)
Article
Chemistry, Physical
Lei Huang, Man Wang, Lichun Cheng, Shunkang Pan, Qingrong Yao, Huaiying Zhou
Summary: Rare-earth orthoferrites (RFeO3) are emerging as a type of microwave absorbing material (MAM) with great potential due to their excellent structural stability and moderate permittivity. In this study, La1-xCaxFeO3 ferrite MAMs were synthesized using a sol-gel technology, showing that an appropriate amount of Ca doping can enhance the microwave absorption of LaFeO3. The ideal microwave absorption was achieved when Ca content x = 0.1 and 0.15, demonstrating the potential of La1-xCaxFeO3 as a high-performance MAM.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Multidisciplinary Sciences
Guixiang Li, Zhenhuang Su, Laura Canil, Declan Hughes, Mahmoud H. Aldamasy, Janardan Dagar, Sergei Trofimov, Luyao Wang, Weiwei Zuo, Jose J. Jeronimo-Rendon, Mahdi Malekshahi Byranvand, Chenyue Wang, Rui Zhu, Zuhong Zhang, Feng Yang, Giuseppe Nasti, Boris Naydenov, Wing C. Tsoi, Zhe Li, Xingyu Gao, Zhaokui Wang, Yu Jia, Eva Unger, Michael Saliba, Meng Li, Antonio Abate
Summary: Daily temperature variations challenge the stability of halide perovskites in solar cells. However, by using the ordered dipolar structure of beta-poly(1,1-difluoroethylene), we were able to stabilize the perovskite black phase and improve solar cell performance. Our p-i-n perovskite solar cells achieved a record power conversion efficiency of 24.6% and retained high efficiency after exposure to various temperatures and thermal cycling.
Article
Materials Science, Multidisciplinary
Young-Seong Kim, Zhengyun Jin, Min Wook Park, Hee Chang Jeon, Joong Yeon Lim
Summary: A high-quality single-phase ultrathin nanofilm organic-inorganic hybrid perovskite nanostructure is proposed, which can control the ferroelectric, ferromagnetic, and piezoelectric properties through an external electric field. This study suggests that high-quality nanostructured perovskites are suitable for high-efficiency multibit devices.
MATERIALS TODAY PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
T. Bolstad, K. Kjaernes, K. Raa, R. Takahashi, M. Lippmaa, T. Tybell
MATERIALS RESEARCH EXPRESS
(2019)
Article
Chemistry, Physical
Seiji Kawasaki, Ryota Takahashi, Mikk Lippmaa
JOURNAL OF PHYSICAL CHEMISTRY C
(2019)
Article
Instruments & Instrumentation
S. Maruyama, N. Sannodo, R. Harada, Y. Anada, R. Takahashi, M. Lippmaa, Y. Matsumoto
REVIEW OF SCIENTIFIC INSTRUMENTS
(2019)
Review
Physics, Applied
Mikk Lippmaa, Seiji Kawasaki, Ryota Takahashi, Takahisa Yamamoto
JAPANESE JOURNAL OF APPLIED PHYSICS
(2020)
Article
Nanoscience & Nanotechnology
Ryota Takahashi, Mikk Lippmaa
ACS APPLIED MATERIALS & INTERFACES
(2020)
Article
Physics, Applied
J. N. Lee, X. Hou, R. Takahashi, M. Lippmaa
APPLIED PHYSICS LETTERS
(2020)
Article
Chemistry, Physical
Rio Konno, Shingo Maruyama, Takumu Kosaka, Ryuzi Katoh, Ryota Takahashi, Hiroshi Kumigashira, Nobuyuki Ichikuni, Hiroshi Onishi, Yuji Matsumoto
Summary: In this study, Sr-doped NaTaO3 (NTO) single-crystalline films with different Sr compositions were successfully fabricated, showing changes in lattice constants and optical absorption edge energies as the Sr doping level increased. The doped Sr atoms were found to substitute for both A and B sites in the crystal structure. Furthermore, compositionally graded Sr-doped NTO films were successfully prepared with different Sr composition gradients, and the lifetime of photoexcited carriers in these films was longer compared to NTO and homogeneous Sr-doped NTO films.
CHEMISTRY OF MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Mikk Lippmaa, Seiji Kawasaki, Ryota Takahashi, Takahisa Yamamoto
Summary: Spontaneous noble metal dopant segregation in an oxide lattice can lead to the formation of metallic clusters and extended acicular inclusions. In a thin-film process, the shape and orientation of such noble metal inclusions are governed by the crystal growth direction, resulting in a composite material with lattice-matched metal nanopillars embedded vertically in an insulating or semiconducting oxide matrix. These vertically aligned metal-oxide nanopillar composites have interesting applications in photoelectrochemical water-splitting cells for direct solar-powered hydrogen generation, where the metallic nanopillars serve multiple roles such as forming a Schottky junction and creating an efficient electrocatalytic active site on the electrode surface.
Article
Chemistry, Multidisciplinary
Ryota Takahashi, Takahisa Yamamoto, Mikk Lippmaa
Summary: The study investigated the moderation of kinetic energy in PLD growth of SrTiO3 thin films using helium buffer gas. By reducing the kinetic energy of the plume, crystal defects were minimized, leading to improved film quality. Helium pressure was found to be crucial in tuning the functional properties of oxide films.
CRYSTAL GROWTH & DESIGN
(2021)
Article
Materials Science, Multidisciplinary
Haotong Liang, Valentin Stanev, Aaron Gilad Kusne, Yuto Tsukahara, Kaito Ito, Ryota Takahashi, Mikk Lippmaa, Ichiro Takeuchi
Summary: The article introduces a phase mapping method based on machine learning analysis of RHEED images, which allows for the extraction of quantitative structural information. The method can automatically identify different RHEED pattern types and is applicable to mapping the structural phase diagram of hematite-magnetite phase boundary.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Shizuka Suzuki, Takuro Dazai, Tomoharu Tokunaga, Takahisa Yamamoto, Ryuzi Katoh, Ryota Takahashi
Summary: This study investigates the effect of structural defect on the luminescence properties of TbxY2-xO3 composition-gradient films. The films were grown using pulsed laser deposition (PLD) on a SrTiO3 (001) substrate. The presence of structural defects in the films significantly weakens the luminescence intensity. Concentration quenching of the luminescence is observed at high Tb concentrations. The study provides insights into the material parameters and offers a pathway for enhancing the luminescence properties.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Physics, Applied
Shizuka Suzuki, Takuro Dazai, Yukio Yamamoto, Hideomi Koinuma, Ryota Takahashi
Summary: This study investigates the acceleration of the combinatorial optimization process for phosphor materials using a machine learning method based on Bayesian optimization. By applying Bayesian optimization to sequential measurements of photoluminescence properties, the researchers were able to significantly reduce the number of measurement points and accelerate material evaluation.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Yuta Sato, Kenichi Kaminaga, Ryota Takahashi, Shingo Maruyama, Yuji Matsumoto
Summary: The impact of band gap-graded structures on the photoelectrochemical properties was investigated, and it was found that the down-graded film exhibited better photoanodic current density and photooxidation ability. These differences are attributed to the graded band structures of the films.
CATALYSIS SCIENCE & TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Shizuka Suzuki, Takuro Dazai, Kazuhiro Kawashima, Tomoharu Tokunaga, Takahisa Yamamoto, Ryota Takahashi
Summary: The feasibility of using a He buffer gas to moderate the kinetic energy of PLD plumes during the growth of EuxY2-xO3 phosphor films was investigated. It was found that the use of He buffer gas successfully reduced crystal defect generation and improved the film characteristics.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Mihee Lee, Remi Arras, Ryota Takahashi, Benedicte Warot-Fonrose, Hiroshi Daimon, Marie-Jose Casanove, Mikk Lippmaa
