Article
Chemistry, Physical
Shulong Chang, Mengya Yang, Rui Pang, Li Ye, Xinchang Wang, Anyuan Cao, Yuanyuan Shang
Summary: The carbon nanotube-anatase titanium dioxide (CNT/a-TiO2) film sensor exhibits good sensitivity, fast response, reversibility, and high selectivity towards toxic gases. Its lightweight and high-performance characteristics make it a promising candidate for future wearable electronics and gas monitoring devices.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Ceramics
Lu Yin, Chuanbin Wang, Qiang Shen
Summary: The growth process of LSMZO films and the effect of adding Zn element on their properties were studied. The results show that increasing Zn content will decrease the Curie temperature and metal-insulator transition temperature of LSMZO, and increase the coercive field and room-temperature resistivity. Analysis of the fraction of Mn3+ and Mn4+ shows that Zn2+ substitution at the Mn site weakens the double-exchange interaction by increasing the Mn4+ fraction. In addition, ionic radius mismatch and substrate-induced strain also affect the performance of LSMZO. Most importantly, enhanced magnetic disorder in the LSMZO (y = 10%) film leads to an increase in intrinsic magnetoresistance around room temperature, and a large magnetoresistance of 18.4% is obtained at 0.3 T and 280 K in this sample.
CERAMICS INTERNATIONAL
(2023)
Article
Chemistry, Multidisciplinary
Thameur Hajlaoui, Catalin Harnagea, Alain Pignolet
Summary: Multiferroic thin films are promising materials that integrate multiple functionalities. Novel multiferroic heterostructures, combining good ferroelectric and ferromagnetic properties and a strong coupling between them, have been developed. Ba2EuFeNb4O15/BaFe12O19 multiferroic magnetoelectric bilayers were epitaxially grown on niobium doped SrTiO3 substrates. The heterostructure demonstrated both ferroelectric and magnetic properties at room temperature, and a strong magnetoelectric coupling was observed. The coupling is mediated by elastic strain at the interfaces.
Article
Materials Science, Ceramics
Mei Ying Liu, Tu Lai Sun, Ting Ting Gao, Zhi Ping Bian, Zhen Lin Luo, Xiao Qiang Liu, Xiang Ming Chen
Summary: This study enhances the ferroelectricity of SmFeO3 thin films by introducing a CaTiO3 blocking layer, and verifies the room-temperature ferroelectricity and magnetoelectric coupling effect.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Physics, Applied
Limin Li, Li Lei, Gaoyang Zhao, Bo Deng, Fuxue Yan, Chengshan Li
Summary: This study aims to develop a reliable and low-cost technique for fabricating coated conductors on flexible substrates, and to understand the effects of oriented growth and microstructure on the superconducting performance in depth. By investigating the gradient buffer architecture and YBCO film on a specific substrate, the relationship between crystal orientation, microstructure, and electrical properties was analyzed, as well as the impact of heat treatment temperature on superconductivity.
SUPERCONDUCTOR SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Multidisciplinary
Fahimeh Shahvardanfard, Gihoon Cha, Nikita Denisov, Benedict Osuagwu, Patrik Schmuki
Summary: Single crystal anatase TiO2 nanosheets were successfully grown hydrothermally on FTO, with different TiO2-NSs morphologies and facet ratios characterized for their photoelectrochemical response. The photocurrent magnitude strongly depends on growth parameters, primarily the effective electrochemically active area of the electrode, while high facet ratios (>91%) can significantly influence the photoresponse. This study provides crucial fundamental data for optimizing the growth of single crystalline electrodes.
NANOSCALE ADVANCES
(2021)
Article
Nanoscience & Nanotechnology
Mehrdad Abbasi, Yutao Dong, Jun Meng, Dane Morgan, Xudong Wang, Jinwoo Hwang
Summary: The evolution of medium range ordering (MRO) and crystallization behavior of amorphous TiO2 films grown by atomic layer deposition were investigated using in situ four-dimensional scanning transmission electron microscopy. The degree of MRO increases with temperature and reaches the maximum when crystallization starts to occur. In addition, post-annealing only develops a small portion of MRO into crystal nuclei, while the remaining MRO regions undergo structural relaxation. Crystallographic defects within crystal phases were observed, which may affect the corrosion resistance of the film. Understanding and controlling MRO is important for optimizing ALD-grown amorphous films for future functional devices and renewable energy applications.
Article
Nanoscience & Nanotechnology
Binjie Chen, Gowoon Kim, Hai Jun Cho, Hiromichi Ohta
Summary: VO2 is a promising candidate material for smart windows due to its optoelectronic properties, but its high T-c needs to be reduced for practical applications. This study demonstrates that M-plane sapphire substrate can decrease the T-c of VO2 to near room temperature, showing potential for large-scale applications. In addition, the insulator-to-metal transition of VO2 is found to be sensitive to in-plane lattice distortion, which can induce carrier generation.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Ardak Ainabayev, Daragh Mullarkey, Brian Walls, David Caffrey, Kuanysh Zhussupbekov, Ainur Zhussupbekova, Cansu Ilhan, Aitkazy Kaisha, Pranab Biswas, Alexander Tikhonov, Oisin Murtagh, Igor Shvets
Summary: The ability of VO2 to undergo semiconductor-to-metal phase transition (SMT) upon heating makes it suitable for uncooled bolometers. However, characteristics such as high transition temperature, sharpness, hysteresis, and high resistivity limit its performance. In this study, high-quality epitaxial ultrathin film VO2 was grown on c-plane Al2O3 by pulsed laser deposition. The control of grain size and oxygen vacancy concentration allowed the adjustment of SMT parameters, and the high density of grain boundaries suppressed thermal hysteresis. This approach provides a simpler and more efficient method for practical bolometer applications.
ACS APPLIED NANO MATERIALS
(2023)
Article
Materials Science, Ceramics
Xiaoping Wu, Yong Liu
Summary: The transformation of anatase titanium dioxide to rutile form is influenced by factors such as heating temperature, heating time, and particle states. The roles of temperature and time in the anatase-rutile transformation for pigmentary TiO2 production are not clearly understood.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Electrical & Electronic
Nila Pal, Utkarsh Pandey, Sajal Biring, Bhola N. Pal
Summary: A top-contact bottom-gated SnO2 thin-film transistor (TFT) has been successfully fabricated using a TiO2/Li-Al2O3 bilayer stacked gate dielectric, with an operating voltage within 2.0 V. The bilayer dielectric shows higher areal capacitance and lower leakage current density, significantly improving the overall device performance of the TFT. Compared to TFTs with a single layer Li-Al2O3 gate dielectric, the TFT with the bilayer gate dielectric exhibits higher effective carrier mobility and on/off ratio.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2022)
Article
Physics, Applied
Chi Zhang, Fengdeng Liu, Silu Guo, Yingying Zhang, Xiaotian Xu, K. Andre Mkhoyan, Bharat Jalan, Xiaojia Wang
Summary: As an ultrawide bandgap semiconductor, single crystalline SrSnO3 (SSO) shows potential for power electronics and transparent conductor applications, but its device performance can be limited by heat dissipation issues. This study investigates the temperature-dependent thermal properties of a single crystalline SSO thin film and provides physical insights into its thermal transport mechanisms. The results reveal that the thermal conductivity of the SSO film is lower than other perovskite oxides at room temperature, attributed to its unique distorted orthorhombic structure. At high temperatures, the thermal conductivity of SSO decreases with temperature following a weaker dependence than typical trends dominated by Umklapp scattering. This work not only improves our understanding of thermal transport in single crystalline SSO but also has implications for the thermal design and optimization of SSO-based electronic applications.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Pritha Biswas, Tamara D. Koledin, Skylar N. Farmer, Melissa K. Santala, Janet Tate
Summary: The transformation from amorphous to crystalline in TiO2 films in air leads to different polymorphs, which can be manipulated by introducing Sn into the system. Sn stabilizes the rutile structure at the Sn/TiO2 interfaces by scavenging oxygen, resulting in rutile formation.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Nanoscience & Nanotechnology
Wondimagegnehu Beshah Begna, Gamachis Sakata Gurmesa, Qinfang Zhang, Chernet Amente Geffe
Summary: This study investigates the effect of Fe doping on the crystal structure, electronic property, and magnetic property of anatase TiO2 through first-principles calculations. The results show that Fe doping can modify the bandgap and Curie temperature of TiO2, leading to ferromagnetic behavior with Tc above room temperature.
Article
Chemistry, Multidisciplinary
Andrew R. Riscoe, Jinwon Oh, Matteo Cargnello
Summary: Dehydration of alcohols is an important reaction class for the development of fossil-free fuel and chemical industries. Acid catalysts enhance the reactivity and selectivity of alcohols. This study investigates the effects of sulfur treatments on TiO2 surfaces for alcohol dehydration. The results show that sulfur treatments improve the activity and selectivity of TiO2 surfaces, and sulfate species on TiO2 surfaces are identified as active sites for the reaction.
Article
Chemistry, Multidisciplinary
Michitaka Fukumoto, Yasushi Hirose, Benjamin A. D. Williamson, Shoichiro Nakao, Koji Kimura, Koichi Hayashi, Yuki Sugisawa, Daiichiro Sekiba, David O. Scanlon, Tetsuya Hasegawa
Summary: It is demonstrated that tungsten is a high-mobility dopant in rutile SnO2, showing minimized ionized impurity scattering. The hybridization between metal d orbitals and O 2p orbitals provides a new guide for designing novel dopants for NIR transparent conductors.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Physics, Applied
Tahta Amrillah, Daichi Oka, Hirokazu Shimizu, Satoshi Sasaki, Daichi Saito, Kenichi Kaminaga, Tomoteru Fukumura
Summary: In this study, a rock salt-type HoO epitaxial thin film was successfully synthesized, which exhibited nontrivial magnetic structure and tunable electrical conduction. Comparing to other related materials, HoO thin film had a higher Curie temperature and showed metamagnetic behavior.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Inorganic & Nuclear
Kyohei Terakado, Hideyuki Kawasoko, Tomoteru Fukumura
Summary: In Y2O2Bi with Bi square net, higher superconducting transition temperatures (T-c) were achieved through H substitution and Li intercalation, while lower T-c was observed with F substitution. Li intercalated Y2O2Bi showed a higher T-c compared to previously reported Y2O2Bi samples with similar c/a.
DALTON TRANSACTIONS
(2022)
Article
Materials Science, Multidisciplinary
Shota Fukuma, Akira Chikamatsu, Tsukasa Katayama, Takahiro Maruyama, Keiichi Yanagisawa, Koji Kimoto, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Yasushi Hirose, Tetsuya Hasegawa
Summary: Layered ruthenium oxyfluorides possess various crystal structures and Ru oxidation states, exhibiting unique physical properties. This study investigates the fluorination process of layered ruthenates containing smaller Ca ions and fabricates phase-pure and single-crystalline thin films of Ca2RuO2.5F2. It finds that local distortion plays a crucial role in the topochemical fluorination of ruthenates and affects the crystal and electronic structures of the reactants.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Chemistry, Physical
Yo Nagashima, Michitaka Fukumoto, Masato Tsuchii, Yuki Sugisawa, Daiichiro Sekiba, Tetsuya Hasegawa, Yasushi Hirose
Summary: Transparent conductive oxides (TCOs) are crucial materials for optoelectronic devices. This article introduces a promising alloy, rutile Sn1-xGexO2 (SGO), as a deep ultraviolet (DUV) TCO material. The Ta-doped rutile SGO thin films demonstrate high potential for DUV-LED applications.
CHEMISTRY OF MATERIALS
(2022)
Article
Chemistry, Inorganic & Nuclear
Zaichun Sun, Shaoyong Qin, Daichi Oka, Huijuan Zhang, Tomoteru Fukumura, Yuji Matsumoto, Bingchu Mei
Summary: Semitransparent and homogeneous bismuth oxychloride (BiOCl) thin films with (001) preferred orientation were synthesized on polycrystalline Sn:In2O3-glass substrates by mist chemical vapor deposition. The films showed photocathodic activity even under near-ultraviolet light within the band gap due to the in-gap states induced by oxygen vacancies. Higher synthesis temperatures resulted in a significant increase of photocurrent density under ultraviolet light. The longer lifetime of photocarriers led to an increase of internal quantum efficiency, while the larger band-edge absorption significantly contributed to the higher external quantum efficiency.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Kota Matsumoto, Hideyuki Kawasoko, Eiji Nishibori, Tomoteru Fukumura
Summary: A reversible switching of room-temperature electrical resistivity was demonstrated in a layered nickelate Sr2.5Bi0.5NiO5, which undergoes unique crystalline phase changes between different structures. This phenomenon has not been reported in transition metal oxides despite their extensive studies on electrical conduction.
Article
Chemistry, Inorganic & Nuclear
Sailaja S. Sunkari, Abhineet Verma, Om Pandey, Shraddha Gupta, Masanori Wakizaka, Shinya Takaishi, Hideyuki Kawasoko, Tomoteru Fukumura, Masahiro Yamashita
Summary: The first slow magnetic relaxation in a ferromagnetic Cu(II) chain compound, Cu(dipic)(OH2)(2), induced by a phonon bottleneck effect under a magnetic field of 0.6 T, with a relaxation time of 2.2 s at 2.8 K, was observed.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Jiyang Huang, Daichi Oka, Yasushi Hirose, Masamichi Negishi, Tomoteru Fukumura
Summary: We grew thin films of Ti0.95Co0.05O2-δ, a room-temperature ferromagnetic semiconductor, on rigid and flexible glass substrates using TiO2 seed layers. The thin films exhibited a preferred (101) orientation and large crystallographic domains of around 50 μm in lateral size, showing clear ferromagnetic hysteresis loops at 300 K. The films also had high electrical conductivity and transparency, allowing for electrical and optical detection of the ferromagnetic signal through the anomalous Hall effect and magneto-optical effect, respectively. Interestingly, flatter films with larger domains were obtained on flexible glass substrates, leading to higher conductivity and larger anomalous Hall signals comparable to epitaxial thin films.
Article
Materials Science, Multidisciplinary
Taiki Taguchi, Katsuaki Sugawara, Hirofumi Oka, Tappei Kawakami, Yasuaki Saruta, Takemi Kato, Kosuke Nakayama, Seigo Souma, Takashi Takahashi, Tomoteru Fukumura, Takafumi Sato
Summary: We discovered that monolayer 1T-NbTe2 is a new class of two-dimensional transition-metal dichalcogenide (TMD) with a star-of-David lattice similar to bulk TaS2 and isostructural monolayer NbSe2. It exhibits a metallic ground state characterized by the sparsely occupied star-of-David lattice with a lattice periodicity of (19x19). By using various techniques, we found that the hidden Fermi-surface nesting and associated CDW formation are the primary causes for this unique correlated metallic state without a Mott gap.
Article
Chemistry, Inorganic & Nuclear
Satoshi Sasaki, Daichi Oka, Kenichi Kaminaga, Daichi Saito, Taku Yamamoto, Nobuto Abe, Hirokazu Shimizu, Tomoteru Fukumura
Summary: This study reports a solid phase rock-salt structured TbO with an unusual valence state of Tb2+. The TbO exhibits narrow gap ferromagnetic semiconductor properties and a high Curie temperature. The experimental results suggest the formation of both 4f and 5d magnetic sublattices at a single magnetic Tb2+ site in TbO.
DALTON TRANSACTIONS
(2022)
Article
Materials Science, Multidisciplinary
Nobuto Abe, Daichi Oka, Kenichi Kaminaga, Daisuke Shiga, Daichi Saito, Taku Yamamoto, Noriaki Kimura, Hiroshi Kumigashira, Tomoteru Fukumura
Summary: Rocksalt CeO (001) epitaxial thin films were synthesized and their electronic properties were investigated. The study confirmed a simple 4 f15d1 electronic configuration and 4 f-5d hybridization in CeO. The results suggested that the significant 4 f-5d hybridization induced a Kondo coherent state in CeO. These findings are important for understanding the electronic behavior of CeO.
Article
Materials Science, Multidisciplinary
Takahiro Maruyama, Yasushi Hirose, Tsukasa Katayama, Yuki Sugisawa, Daiichiro Sekiba, Tetsuya Hasegawa, Akira Chikamatsu
Summary: The perovskite-type europium niobium oxynitride (EuNbO2N) exhibits colossal negative magnetoresistance at low temperatures, and the negative MR ratio increases with nitrogen content. The transport properties of EuNbO3-xNx thin films change gradually from metallic to semiconducting as the nitrogen content increases, which is attributed to carrier localization caused by the random distribution of nitrogen at anion sites. The d-f exchange interaction between localized Nb 4d(1) and Eu2+ 4f electrons is speculated to be a key factor in the colossal negative MR of EuNbO3-xNx.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Hirokazu Shimizu, Daichi Oka, Kenichi Kaminaga, Daichi Saito, Taku Yamamoto, Nobuto Abe, Noriaki Kimura, Daisuke Shiga, Hiroshi Kumigashira, Tomoteru Fukumura
Summary: A unique praseodymium monoxide PrO in the form of an epitaxial thin film has been synthesized. The PrO thin films, with a rocksalt structure and a 4f(2)5d(1) electronic configuration, exhibit metallic conduction and a local resistivity minimum at 7 K due to the Kondo effect. In contrast to other praseodymium monochalcogenides, PrO displays weak ferromagnetism below 28 K, which transitions to a more ferromagnetic-like phase around 5 K. The weak ferromagnetism is likely a result of enhanced 4f-4f exchange interaction due to the short Pr-Pr distance. In the ferromagnetic-like phase below 5 K, the magnetic hysteresis of the anomalous Hall effect is significantly larger than that of magnetization, possibly due to competing magnetic ordering.
