Article
Materials Science, Ceramics
Junmeng Zhang, Jianmin Lu, Panzhe Hou, Peipei Lu, Lingna Jia, Zhiyun Yang, Lihu Liu, Huiyuan Sun
Summary: Undoped porous WO3 nanofilms with large surface area were successfully fabricated by magnetron sputtering. These nanofilms exhibited significant room-temperature ferromagnetism and the saturation magnetization could be controlled by adjusting the deposition conditions. The porous samples showed magnetic anisotropy related to the regular pore structure and annealed nanofilms displayed narrowed bandgap and enhanced ferromagnetism, which can be explained by hydrogen-like impurity states associated with oxygen vacancies.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2023)
Review
Nanoscience & Nanotechnology
Hui-Chuan Liu, Si-Ming Zeng, Rui Li, Yan-Ping Jiang, Qiu-Xiang Liu, Xin-Gui Tang
Summary: The study demonstrated bipolar resistive switching and ferroelectricities of Ni0.5Zn0.5Fe2O4 (NZFO) thin films using Au/NZFO/LNO/Si structure. It was found that annealing atmosphere influences the structure and properties of NZFO, with oxygen vacancy and strain stress playing a significant role. The saturation magnetization and remnant polarization values of the samples were affected by the annealing atmosphere, with improved resistive switching property observed in NZFO annealed in nitrogen atmosphere.
ADVANCED COMPOSITES AND HYBRID MATERIALS
(2021)
Article
Materials Science, Multidisciplinary
Xiaodong Zhou, Erlei Wang, Xiaodong Lao, Yongmei Wang, Honglei Yuan
Summary: This study investigated room temperature ferromagnetic Cu-doped LiNbO3 thin films and found that the activation of ferromagnetism may be attributed to indirect interactions between oxygen vacancies and dopant ions. The results contribute to elucidating the origin of ferromagnetism in perovskite ferroelectric oxides.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Physical
D. Paul Joseph, U. Devarajan, Jean Maria Fernandes, R. Ramarajan, M. Kovendhan, Nandarapu Purushothamreddy, Reddivari Muniramaiah, C. Venkateswaran
Summary: Transparent conducting thin film electrodes of undoped, Sb doped, and Li-Sb co-doped SnO2 were prepared by spray pyrolysis. The co-doped LATO5 film demonstrated enhanced electrical transport properties, high carrier concentration, high mobility, and low resistivity, making it a potential candidate for alternative transparent conducting electrode systems. The surface morphology, transmittance spectra, and electrical conductivity of the films were analyzed to evaluate their performance.
SURFACES AND INTERFACES
(2021)
Article
Materials Science, Ceramics
Xudong Zheng, Liang Wu, Feng Ren
Summary: Room-temperature ferromagnetism in WO3 films was enhanced by Ar+ ion irradiation, forming oxygen vacancy defects and induced W5+ ions. The saturation magnetization doubled at the highest fluence.
CERAMICS INTERNATIONAL
(2021)
Article
Nanoscience & Nanotechnology
Alessandro R. Mazza, Qiyang Lu, Guoxiang Hu, Haoxiang Li, James F. Browning, Timothy R. Charlton, Matthew Brahlek, Panchapakesan Ganesh, Thomas Zac Ward, Ho Nyung Lee, Gyula Eres
Summary: We report on the mechanism of hydrogen-induced topotactic phase transitions in perovskite oxides using La0.7Sr0.3MnO3 as an example. The hydrogenation causes lattice expansion and changes in electronic structure, leading to a metal-insulator transition. The ordering of oxygen vacancies induces a phase transition from perovskite to brownmillerite. This study reveals the significant impact of hydrogen-induced oxygen vacancy formation on the properties of perovskite oxides.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Spectroscopy
Yuze Shi, Qingyou Liu, Ruijin Hong, Chunxian Tao, Qi Wang, Hui Lin, Zhaoxia Han, Dawei Zhang
Summary: WO3-x thin films with defects were obtained through thermal treatments from laser irradiation and annealing, leading to tunability of localized surface plasmon resonance properties and enhancement of Raman scattering intensity. By adjusting laser power or annealing temperature, the crystalline quality of WO3-x thin film decreased and the surface plasmon resonance wavelength red shifted from 464 nm to 482 nm. The treated WO3-x film exhibited good uniformity and reproducibility in Surface-enhanced Raman spectroscopy measurement, with a detection limit for dye methylene blue reaching 10(-8) mol/L and an enhancement factor of 1.38 x 10(6).
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Chemistry, Physical
F. Mazzola, H. Hassani, D. Amoroso, S. K. Chaluvadi, J. Fujii, V. Polewczyk, P. Rajak, Max Koegler, R. Ciancio, B. Partoens, G. Rossi, I. Vobornik, P. Ghosez, P. Orgiani
Summary: WO3 is a versatile compound that undergoes structural transitions, with various applications such as flexopiezoelectricity, electrochromism, and improving Li-based battery performance. The synthesis of WO3 thin films holds promise for stabilizing electronic phases, but its electronic structure remains unexplored experimentally. This study investigates the electronic structure of strained WO3 thin films and reveals the Fermiology of the system, with significant energy splittings due to atomic distortions. These splittings and the system's thermal stability offer potential for controlling inter- and intraband scattering in electronic applications.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Nanoscience & Nanotechnology
Mei Ying Liu, Jun Xi Yu, Xiao Li Zhu, Zhi Ping Bian, Xiang Zhou, Yu Hang Liang, Zhen Lin Luo, Yue Wei Yin, Jiang Yu Li, Xiang Ming Chen
Summary: In this study, h-Lu1-xInxFeO3 thin films were successfully prepared with a stable hexagonal structure achieved at room temperature. The films exhibited high remanent polarization and excellent polarization switching performance, along with a strong magnetoelectric coupling effect. These results demonstrate the potential application of h-Lu1-xInxFeO3 thin films in magnetoelectric memory and detection devices.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Acoustics
Maya D. Glinchuk, Anna N. Morozovska, Lesya P. Yurchenko
Summary: The study investigates the ferroelectric, ferromagnetic, and ferroelastic phases in thin films of binary oxides and their relation to oxygen vacancies. It suggests that these films can be considered as new multiferroics with potential applications in nanoelectronics and nanotechnology. Control of properties can be achieved through factors such as oxygen vacancy concentration, film thickness, and technological treatment like annealing.
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
(2021)
Article
Materials Science, Ceramics
Xu Jiang, Jie Sun, Xiaojie Chai, Yifan Chen, Wei Zhang, Jun Jiang, Anquan Jiang
Summary: The study found that the wall current varies with the angle between the applied electric field and the initial polarization, and that the oxygen vacancy concentration can be controlled through thermal annealing, affecting the magnitude of the domain wall current.
CERAMICS INTERNATIONAL
(2021)
Article
Chemistry, Physical
Guanglu Lei, Zishuo Li, Guocai Lu, Jinyuan Hu, Haochuan Shang, Xiaolei Zhang, Xianghong Liu, Jun Zhang, Xiangxin Guo
Summary: Metal oxide semiconductor (MOS) thin films, especially tungsten oxide (WO3) thin films, have shown great potential as sensing layers for gas sensor devices. This study focuses on the deposition and annealing process of WO3 thin films on interdigital electrodes, and explores the impact of oxygen vacancies on sensor properties. The results indicate that the WO3 sensor annealed at 500 degrees C exhibits the best performance in detecting triethylamine (TEA), which is attributed to the enhanced adsorption of oxidative oxygen species due to the presence of abundant oxygen vacancies.
JOURNAL OF MATERIOMICS
(2022)
Article
Materials Science, Multidisciplinary
Satoshi Kodama, Yoshiaki Miyamoto, Shun Itoh, Takashi Miyata, Hiroaki Wada, Kazuyuki Kuroda, Atsushi Shimojima
Summary: In this study, self-healing silsesquioxane thin films were designed by the self-assembly process, showing efficient spontaneous and rapid crack healing. These films demonstrated significantly enhanced crack-healing ability, hardness, and adhesion compared to conventional silica-based films, due to the higher flexibility and swelling ratio of the silsesquioxane networks, as well as the interlamellar cross-linking with a long bridging organic group. These results will contribute to the practical applications of self-healing silsesquioxane materials.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Materials Science, Coatings & Films
Mohsin Raza, Pascal Boulet, Jean-Francois Pierson, Rony Snyders, Stephanos Konstantinidis
Summary: The thermal stability of reactive magnetron sputter deposited oxygen vacancy stabilized cubic zirconia thin films has been studied, showing stability up to 750 degrees Celsius but structural transformation to monoclinic phase at higher temperatures due to compressive stresses caused by differences in thermal expansion coefficients between the film and substrate. Thermal cycling experiments at 700 degrees Celsius demonstrated that the films retained their initial cubic structure.
SURFACE & COATINGS TECHNOLOGY
(2021)
Article
Chemistry, Physical
Waleed Ahmad, Eunseuk Park, Heehyeon Lee, Jin Young Kim, Byoung Chan Kim, Jongsoo Jurng, Youngtak Oh
Summary: Synthesizing defective anatase TiO2 through chemical vapor condensation and impregnating with Pt resulted in a Pt/CVC-TiO2 catalyst with high efficiency in removing HCHO at room temperature, demonstrating good stability over time. The study highlighted the synergistic relationship between oxygen vacancies in the TiO2 support and the resulting HCHO oxidation functionality.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
C. da Cruz, R. C. de Oliveira, I. T. Neckel, D. H. Mosca, J. Varalda
JOURNAL OF PHYSICAL CHEMISTRY C
(2019)
Article
Materials Science, Multidisciplinary
V. Z. C. Paes, D. H. Mosca, A. J. A. de Oliveira, J. Varalda
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2020)
Article
Materials Science, Multidisciplinary
R. S. Santiago, L. C. D. Silva, F. D. Origo, C. Stegemann, I. L. Graff, R. G. Delatorre, D. A. Duarte
Article
Chemistry, Physical
Greici Gubert, Jose Varalda, Dante H. Mosca
Summary: Iron nitride nanostructures were successfully synthesized using Nd:YAG laser in liquid nitrogen, forming single-phase alpha ''-Fe16N2, zeta-Fe2N, and epsilon-Fe3N nanostructures or a mixture of them. Varying the laser fluence allowed for obtaining different phases, and specific laser frequencies were found to be effective in producing complex iron nitride phases.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Physics, Condensed Matter
S. J. Gutierrez-Ojeda, R. C. de Oliveira, H. N. Fernandez-Escamilla, R. Ponce-Perez, J. Guerrero-Sanchez, D. H. Mosca, Gregorio H. Cocoletzi, J. Varalda
SUPERLATTICES AND MICROSTRUCTURES
(2020)
Article
Materials Science, Multidisciplinary
Shih-Chieh Lin, Cheng-Tai Kuo, Yu-Cheng Shao, Yi-De Chuang, Jaap Geessinck, Mark Huijben, Jean-Pascal Rueff, Ismael L. Graff, Giuseppina Conti, Yingying Peng, Aaron Bostwick, Eric Gullikson, Eric Gullikson, Slavomir Nemsak, Arturas Vailionis, Nicolas Gauquelin, Johan Verbeeck, Giacomo Ghiringhelli, Claus M. Schneider, Charles S. Fadley
PHYSICAL REVIEW MATERIALS
(2020)
Article
Physics, Applied
R. C. de Oliveira, V. Z. C. Paes, D. H. Mosca, J. Varalda
Summary: The magnetic properties of Fe100-xGax (x=15 and 30) epitaxial thin films on GaAs(001) substrates were studied experimentally and theoretically, showing that the relative positions of Fe and Ga atoms affect the magnetic behavior. It was found that due to the high Ga content, the hybridization of Ga 4p states with Fe 4p states leads to the formation of non-bonding Fe 3d states, causing the observed magnetic behavior.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Physical
A. J. Salvador, I. T. Neckel, D. S. Costa, I. L. Graff, D. H. Mosca
Summary: The study investigated the low temperature annealing effect on Ni2MnGa alloy thin films, revealing that an increase in crystalline texture leads to an increase in surface roughness, while residual stress remains even after low temperature annealing.
Article
Materials Science, Multidisciplinary
R. Cardoso de Oliveira, D. Demaille, N. Casaretto, Y. J. Zheng, M. Marangolo, D. H. Mosca, J. Varalda
Summary: Mn5Ge3 thin films were grown on GaAs(111) and GaAs(001) by Molecular Beam Epitaxy (MBE), with the influence of stoichiometry and alloying investigated using different Mn diffusion cell temperatures for each sample. X-ray diffraction (XRD) measurements revealed the epitaxial relations, while high-resolution transmission electron microscopy (HRTEM) results showed grains with different orientations and energy-filtered transmission electron microscopy (EFTEM) analysis indicated similar manganese content in all grains. The magnetocaloric effect in both sample families exhibited broader temperature range and higher magnetic entropy change peak compared to bulk Mn5.1Ge2.9, making Mn5Ge3 a potential candidate for magnetic refrigeration without using rare earth materials.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Physical
A. J. Salvador, I. T. Neckel, I. L. Graff, D. H. Mosca
Summary: The chemical disorder in magnetic shape memory alloys has a significant impact on their properties. This study deposited Ni2MnGa thin films on flexible glass substrates using DC magnetron sputtering and investigated the short-range order/disorder through X-ray absorption measurements. The results reveal the persistence of local tetragonal distortions, decrease of anti-site disorder, and substitutions between Ni and Ga atoms with increasing annealing temperatures.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Review
Physics, Applied
Ravel de Moraes Telles Araujo, Juliana Zarpellon, Dante Homero Mosca
Summary: The aim of this work is to provide an overview and critical discussion on two-dimensional materials and functional nanostructures with ferromagnetic and antiferromagnetic long-range ordering at or above room temperature. The authors specifically describe and discuss the series of results concerning two-dimensional magnetism originating from intrinsic and induced magnetic moments in low-dimensional nanostructured materials. The selected materials exhibiting two-dimensional magnetic properties close to room temperature are classified into atomic monolayers, natural and artificial van der Waals layers, magneto-lamellar intermetallic compounds, and nanostructured materials with native and artificially created defects that produce magnetic moments in two-dimensional networks. The authors also explore the atomic and electronic structures of these materials, as well as the magnetic interaction mechanisms responsible for their magnetic behavior. Theoretical backgrounds for understanding the correlations between structure and magnetic properties are examined. Special emphasis is placed on the potential applications of two-dimensional magnetism in the development of new devices in various emerging technologies such as spintronics, spin-orbitronics, magnonics, valleytronics, and twistronics.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
A. Pichorim, I. T. Neckel, A. J. A. De Oliveira, J. Varalda, D. H. Mosca
Summary: Oxygen-defective gallium oxide thin films with cubic spinel structure were prepared by adjusting the oxygen partial pressure, exhibiting ferromagnetic-like behavior at room temperature. The presence of oxygen vacancies and defects is likely the origin of the unconventional magnetic behavior. These results expand the applications of gallium oxide.
MATERIALS CHEMISTRY AND PHYSICS
(2022)
Article
Physics, Condensed Matter
N. Melenek, J. Varalda
Summary: Calculations based on density functional theory were conducted to investigate the potential of rare earth free Fe5Ge3 magnets in spintronics. The evaluation of spin polarization and magnetic anisotropy was performed for pure Fe5Ge3 and doped Fe5Ge3 with Mn, Co, and Ni atoms. The results showed that the pure system had a spin polarization of 28% at the Fermi level. Doping with Co, Ni, and Mn atoms resulted in an increased spin polarization, with the maximum value of 57% achieved by Co doping at type-I sites. Doping also allowed for control of magnetocrystalline anisotropy, indicating the suitability of the Fe5Ge3 system for spintronic applications.
SOLID STATE COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Cheng-Tai Kuo, Shih-Chieh Lin, Jean-Pascal Rueff, Zhesheng Chen, Irene Aguilera, Gustav Bihlmayer, Lukasz Plucinski, Ismael L. Graff, Giuseppina Conti, Ivan A. Vartanyants, Claus M. Schneider, Charles S. Fadley
Summary: This study investigated the bulk band structure of a topological insulator Bi2Se3 and identified the dominant contributions of Bi 6s, Bi 6p, and Se 4p states to the valence band. Using SW-HAXPES technique, the element-resolved information was extracted, providing a foundation for exploring the element-resolved band structure and orbital contributions of this class of TIs.
Article
Multidisciplinary Sciences
J. Varalda, C. A. Dartora, P. C. de Camargo, A. J. A. de Oliveira, D. H. Mosca
SCIENTIFIC REPORTS
(2019)
