Article
Chemistry, Physical
Berit H. H. Goodge, Benjamin Geisler, Kyuho Lee, Motoki Osada, Bai Yang Wang, Danfeng Li, Harold Y. Y. Hwang, Rossitza Pentcheva, Lena F. F. Kourkoutis
Summary: Nickel-based superconductors provide an experimental platform for exploring cuprate-like superconductivity. However, superconductivity in nickelates has only been observed in thin films, which raises questions about the polar interface between substrate and film. In this study, the authors investigate the interface between Nd1-xSrxNiO2 and SrTiO3 using advanced characterization techniques and theoretical calculations, revealing the formation of a single intermediate Nd(Ti,Ni)O-3 layer and its role in reducing interface charge density. Understanding the complex interface structure is important for the future synthesis of nickelate films on other substrates and in vertical heterostructures.
Article
Chemistry, Physical
Joana M. Ribeiro, Frederico J. Rodrigues, Filipe C. Correia, Inga Pudza, Alexei Kuzmin, Aleksandr Kalinko, Edmund Welter, Nuno P. Barradas, Eduardo Alves, Alec P. LaGrow, Oleksandr Bondarchuk, Alexander Welle, Ahmad Telfah, Carlos J. Tavares
Summary: Transparent ZnO:Sb thin films were deposited using magnetron sputtering, and their structure and disorder were studied. It was found that Sb doping influenced the crystalline structure and promoted partial amorphization. A film with 12 at% of Sb exhibited the highest Seebeck coefficient and thermoelectric power factor.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Chemistry, Physical
Ying-Rui Lu, K. Thanigai Arul, Da-Hua Wei, Cheng-Jie Yang, Yu-Cheng Huang, Chi-Liang Chen, Jeng-Lung Chen, Chung-Li Dong, Wu-Ching Chou
Summary: The study indicates the potential application of gasochromic bare and Mo-V2O5 thin films in smart windows and their relationship between transmittance and color states. Through in situ XAS analysis, the coloration mechanism is deeply explored from the perspectives of atomic and electronic structures, paving the way for the development of advanced chromogenic smart windows.
APPLIED SURFACE SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Fatima Alarab, Karol Hricovini, Berengar Leikert, Laurent Nicolai, Mauro Fanciulli, Olivier Heckmann, Christine Richter, Lucie Prusakova, Zdenek Jansa, Pavol Sutta, Julien Rault, Patrick Lefevre, Michael Sing, Matthias Muntwiler, Ralph Claessen, Jan Minar
Summary: The electronic properties of SrTiO3 doped with Ni impurities were investigated through a combination of photoelectron spectroscopy and first-principles calculations, confirming the formation of localized 3d-impurity bands in the band gap of SrTiO3.
Article
Materials Science, Multidisciplinary
Jingdong Shen, Huihui Zhao, Baofu Song, Ruobai Liu, Jun Du, Qingyu Xu, Qi Li
Summary: In this study, the electronic structures and magnetic properties of SmFeO3 powders and thin films were investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy. Differences in the valence states and chemical compositions were observed between the powders and thin films, leading to variations in exchange bias effects.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Physical
Filipe C. Correia, Joana M. Ribeiro, Alexei Kuzmin, Inga Pudza, Aleksandr Kalinko, Edmund Welter, Adelio Mendes, Joana Rodrigues, Nabiha Ben Sedrine, Teresa Monteiro, Maria Rosario Correia, Carlos J. Tavares
Summary: Doped ZnO thin films with Ga3+ and Bi3+ ions exhibit distinct effects on the microstructure, with Ga3+ introducing static disorder and Bi3+ likely located at grain boundaries. Ga-doping results in compositional disorder, while Bi is not incorporated in the ZnO wurtzite cell but segregated to grain boundaries.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Sourav Chowdhury, Ram J. Choudhary, Deodatta M. Phase
Summary: The research investigates the origin of magnetic interaction in SrCoO2.75 and SrCoO3 thin films by analyzing their experimental valence band (VB) and conduction band (CB). It is found that negative charge transfer energy contributes to the lowest energy charge fluctuations, with a larger effect in SrCoO2.75 film. Magnetic exchange interactions are realized from a model derived from combined VB-CB spectra and Co L-edge absorption spectra, offering valuable insight into the correlation between microscopic electronic structure and macroscopic magnetization in negative double-exchange ferromagnetic oxides.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Nanoscience & Nanotechnology
G. De Luca, J. Spring, U. Bashir, M. Campanini, R. Totani, C. Dominguez, A. Zakharova, M. Dobeli, T. Greber, M. D. Rossell, C. Piamonteze, M. Gibert
Summary: The study shows that LNMO thin films maintain insulating behavior and a stable Curie temperature, regardless of the epitaxial strain conditions. This suggests that this material could be used in multi-layer device architectures that require a high-temperature ferromagnetic insulating state.
Article
Chemistry, Physical
Yanna Chen, Osami Sakata, Hiroyuki Morita, Akifumi Matsuda, Fanhao Jia, Okkyun Seo, Loku Singgappulige Rosantha Kumara, Toshiaki Ina, Eiichi Kobayashi, Jaemyung Kim, Chulho Song, Satoshi Hiroi, Natalia Palina, Yanfang Lou, Wei Ren, Mamoru Yoshimoto
Summary: The study of amorphous, crystallized, and Mg-doped beta-Ga2O3 thin films reveals that the atomic arrangement and electron density change during the evolution of electronic states in the films, affecting the band gap structure and properties. The Mg doping introduces a deficiency in the tetrahedral structure and alters the interaction between Ga and O atoms, leading to a slightly smaller band gap in the doped film. These findings can be valuable for the design of more efficient semiconductive films.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Anupam Jana, Sophia Sahoo, Sourav Chowdhury, Arup Kumar Mandal, Santosh Bimli, Rupesh S. Devan, R. J. Choudhary, D. M. Phase, A. K. Raychaudhuri
Summary: The electronic structure of pulsed laser deposited LaNixV1-xO3 thin films at room temperature has been studied. The shift of the Ni 3d-O 2p hybridized band in Ni-doped LaVO3 films indicates a change in charge transfer energy in the system.
Article
Chemistry, Physical
Raphael da Silva Alvim, Itamar Borges Jr., Rita Maria Brito Alves, Rodrigo B. Capaz, Alexandre Amaral Leitao
Summary: The effects of charged defects at the MgO/Ag interface have been investigated, showing that negative charges decrease the metal work function and result in stronger adsorption of polar molecules at oxygen sites. These findings provide insights into more efficient pathways for CO2 conversion catalysts.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Katarzyna Plachete, Anna Kot, Joanna Banas-Gac, Marcin Zajac, Marcin Sikora, Marta Radecka, Katarzyna Zakrzewska
Summary: Titanium oxide thin films were deposited using rf magnetron sputtering, and their crystallographic structure, phase composition, morphology, and optical properties were extensively studied. It was found that the microstructure of the films changed with the O2 flow ratio, and promising photoanode materials for green hydrogen generation were identified.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Weon Cheol Lim, Jitendra Pal Singh, Younghak Kim, Jonghan Song, Keun Hwa Chae, Tae-Yeon Seong
Summary: The study shows that thermal annealing significantly affects the properties of zinc oxide thin films, including relaxation of stress, variation in optical band-gap, and occurrence of vacancies and defects. These changes are revealed through X-ray techniques, providing a better understanding of the performance changes in zinc oxide films.
Article
Materials Science, Multidisciplinary
P. A. Chate, D. J. Sathe, S. L. Hake
Summary: Nickel selenide thin films were synthesized on amorphous templates using a dip method. The films exhibited polycrystalline nature and high absorptivity with a direct type of transition.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2022)
Article
Chemistry, Physical
Alexandre Mesquita, Elio Thizay Magnavita Oliveira, Hugo Bonette de Carvalho
Summary: Gadolinium-doped strontium titanate (Sr1-xGdxTiO3) is a perovskite structure material with interesting thermomechanical, termoelectrical, and electrochemical properties. X-ray absorption spectroscopy was used to analyze the local and electronic structure of Sr1-xGdxTiO3 samples, showing that increasing Gd content causes disorder and leads to a small displacement of Ti atoms. Changes in the XANES spectra at O K-edge for Sr1-xGdxTiO3 samples are influenced by the increase in Gd concentration.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Physical
Ahmad Kharrat, Bianca Brandstatter, Mostafa Borji, Rene Ritter, Pit Arnold, Gerhard Fritz-Popovski, Oskar Paris, Holger Ott
Summary: The study investigated emulsification and miscibility during surfactant flooding, finding that oil is solubilized and transported into a foam-like textured phase, dependent on salinity and surfactant efficiency. This suggests potential mechanisms for stabilizing such macroemulsions in porous media and highlights the need for further research on mobility control during surfactant flooding.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Chemistry, Physical
Mostafa Borji, Ahmad Kharrat, Holger Ott
Summary: This study investigates the emulsification of crude oil by alkaline solutions using X-ray attenuation and microfluidic experiments. The findings reveal that the emulsifications in test tubes and in porous media flow are comparable, and a minimum emulsion volume with balanced compositions leads to optimal oil recovery.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
Patrick Rupprecht, Lennart Aufleger, Simon Heinze, Alexander Magunia, Thomas Ding, Marc Rebholz, Stefano Amberg, Nikola Mollov, Felix Henrich, Maurits W. Haverkort, Christian Ott, Thomas Pfeifer
Summary: The study introduces a method to control electronic exchange interactions by coupling excited states and demonstrates this concept through experiments on the SF6 molecule. The results show that increasing the intensity of infrared laser can enhance the effective exchange energy between the core hole and the excited electron.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Inorganic & Nuclear
Antoine Maignan, Jacqueline-Nadine Jiongo-Dongmo, Christine Martin, O. I. Lebedev, Francoise Damay, Xiao Wang, Chang-Yang Kuo, Chun-Fu Chang, Zhiwei Hu, Liu Hao Tjeng
Summary: In this study, the Fe4-xNixNb2O9 material was analyzed using various experimental methods. It was found that the structure of the material remains unchanged as nickel substitutes for iron, but there is a decrease in the unit cell volume. Fe3NiNb2O9 has a lower antiferromagnetic transition temperature than Fe4Nb2O9, and below this temperature, its magnetization and electric polarization show a stronger dependence on magnetic field.
SOLID STATE SCIENCES
(2022)
Article
Multidisciplinary Sciences
Haoliang Huang, Yu-Chung Chang, Yu-Cheng Huang, Lili Li, Alexander C. Komarek, Liu Hao Tjeng, Yuki Orikasa, Chih-Wen Pao, Ting-Shan Chan, Jin-Ming Chen, Shu-Chih Haw, Jing Zhou, Yifeng Wang, Hong-Ji Lin, Chien-Te Chen, Chung-Li Dong, Chang-Yang Kuo, Jian-Qiang Wang, Zhiwei Hu, Linjuan Zhang
Summary: LiNiO2 catalyst exhibits super-efficient activity during the oxygen evolution reaction (OER) due to the formation of double O 2p holes states, as observed by operando XAS, XRD, and Raman spectroscopy. Designing efficient OER catalysts is crucial for energy conversion devices.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Hebatalla Elnaggar, Abhishek Nag, Maurits W. Haverkort, Mirian Garcia-Fernandez, Andrew Walters, Ru-Pan Wang, Ke-Jin Zhou, Frank de Groot
Summary: In this study, the observation of triple-magnon excitation in alpha-Fe2O3 challenges the conventional wisdom that only 1- and 2-magnon excitations are possible in a resonant inelastic X-ray scattering experiment. The researchers demonstrate how a two-photon scattering process can generate exotic higher-rank magnons and discuss the relevance of these quasiparticles for magnon-based applications.
NATURE COMMUNICATIONS
(2023)
Article
Physics, Multidisciplinary
D. Takegami, A. Tanaka, S. Agrestini, Z. Hu, J. Weinen, M. Rotter, C. Schuessler-Langeheine, T. Willers, T. C. Koethe, T. Lorenz, Y. F. Liao, K. D. Tsuei, H. -j. Lin, C. T. Chen, L. H. Tjeng
Summary: The electronic structure of LaCoO3 in the gradual spin-state and insulator-to-metal transitions was investigated using bulk-sensitive hard x-ray photoelectron and soft x-ray absorption spectroscopies. The temperature variation was found to cause strong variations in the spectra. Although the energy gap is reduced with increasing temperature, LaCoO3 is classified as a bad metal even in the metallic phase due to the small intensity near the Fermi level. By considering incoherent sums of low-spin and high-spin Co3+ spectra, the spectra were successfully explained. Moreover, it was discovered that the energy parameters for the two Co sites are significantly different, indicating the highly inhomogeneous nature of paramagnetic LaCoO3 with spin-state-specific local lattice relaxations. This provides a natural explanation for the debated temperature dependence of the activation energy for the transitions.
Article
Materials Science, Multidisciplinary
Yosuke Nonaka, Yuki K. Wakabayashi, Goro Shibata, Shoya Sakamoto, Keisuke Ikeda, Zhendong Chi, Yuxuan Wan, Masahiro Suzuki, Arata Tanaka, Masaaki Tanaka, Atsushi Fujimori
Summary: We studied the electronic and magnetic states of MFe2O4(111)/Al2O3(111) (M = Co, Ni) thin films grown on Si(111) substrates with gamma-Al2O3(111) buffer layers using x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD). The magnetically dead layers near the interface were formed in the as-grown samples, but ferrimagnetic order was partially recovered by annealing. Analysis of the XAS and XMCD spectra revealed that the dead layers have a significant number of vacancies at the Td sites of the spinel structure.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Engineering, Chemical
Mostafa Borji, Ahmad Kharrat, Holger Ott
Summary: In situ saponification of crude oil lowers interfacial tensions and forms emulsion phases, affecting fluid distribution and displacement efficiency. Coreflood experiments using μCT showed that Lorentz analysis is useful in characterizing displacement efficiency, and additional oil recovery toward optimal conditions comes from smaller pores.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Materials Science, Multidisciplinary
T. Miyoshino, D. Takegami, A. Melendez-Sans, R. Nakamura, M. Yoshimura, K. -d. Tsuei, K. Takasu, T. Okuda, L. H. Tjeng, T. Mizokawa
Summary: We have investigated the Ti3+/Ti4+ mixed valence state in Mg-doped Ti2O3 using hard x-ray photoemission spectroscopy. The Ti 2p spectrum of corundum-type Ti2O3 indicates the presence of Ti3+ configuration with strong electronic coupling in the c-axis Ti-Ti pairs, while the data for ilmenite-type MgTiO3 confirms the Mg2+-Ti4+ charge state in the c-axis cation pairs. In Mg0.29Ti1.71O3, the Ti 2p spectrum hardly shows the Ti4+ peak, indicating the c-axis pairing of Mg with Ti3+ instead of Ti4+ and the realization of Ti3+/Ti4+ mixed valence state within the Ti-Ti c-axis pairs. In Mg0.63Ti1.37O3, the presence of Mg2+-Ti4+ pairs is detected. The results highlight the significance of hybridization within the c-axis pairs not only in the Ti3+-Ti3+ configuration, but also in the Ti3+/Ti4+ mixed valence state, surpassing the Madelung energy gain of Mg2+-Ti4+ c-axis pair formation.
Article
Materials Science, Multidisciplinary
Jianfa Zhao, Shu-Chih Haw, Xiao Wang, Lipeng Cao, Hong-Ji Lin, Chien-Te Chen, Christoph J. Sahle, Arata Tanaka, Jin-Ming Chen, Changqing Jin, Zhiwei Hu, Liu Hao Tjeng
Summary: We have conducted x-ray absorption spectroscopy at the lead L3 and chromium L2,3 edges to investigate the local electronic structure of PbCrO3. Our findings show that lead is divalent and chromium is charge-disproportionated into trivalent and hexavalent states at ambient pressures, explaining their insulating behavior. The study of the high-resolution partial fluorescence yield of lead L3 spectra as a function of pressure reveals that the divalent state of lead ions remains unchanged at high pressures, when PbCrO3 changes into metal and its volume collapses by more than 10%. We infer that the insulator-to-metal transition does not involve a Pb-Cr charge transfer, but is associated with the conversion of Cr3+/Cr6+ charge-disproportionated states into a Cr4+ valence state.
Article
Chemistry, Inorganic & Nuclear
Marius Retegan, Sadaf Fatima Jafri, Leonardo Curti, Laurent Lisnard, Edwige Otero, Eric Riviere, Maurits W. Haverkort, Anne Bleuzen, Philippe Sainctavit, Marie-Anne Arrio
Summary: This study investigates the contribution of the orbital magnetic moment to magnetization in a potassium hexacyanoferrate(III) sample using X-ray magnetic circular dichroism and molecular multiconfigurational ab initio calculations. The results demonstrate a significant proportion of the total magnetization attributed to the orbital magnetic moment, which is exceptional for 3d transition metal ions. The study also analyzes the impact of crystal field strength and distortion, pi back-bonding, spin-orbit coupling, and external magnetic induction on the spin and orbital magnetic anisotropies, providing a deeper understanding of these phenomena.
INORGANIC CHEMISTRY
(2023)
Article
Optics
Patrick Rupprecht, Lennart Aufleger, Simon Heinze, Alexander Magunia, Thomas Ding, Marc Rebholz, Stefano Amberg, Nikola Mollov, Felix Henrich, Maurits W. Haverkort, Christian Ott, Thomas Pfeifer
Summary: This study measures molecular vibrations with femtometer precision using time-resolved x-ray absorption spectroscopy and relates the measured energy shifts to internuclear distances through many-body ab initio simulation of electronic contributions.
Article
Engineering, Chemical
Mostafa Borji, Ahmad Kharrat, Holger Ott
Summary: In situ saponification of crude oil can effectively reduce the interfacial tension in oil-water systems, resulting in the formation of emulsion phases. This leads to changes in the fluid distribution in the pore space, which directly impact oil displacement efficiency. Through mu CT-based coreflood experiments, it was found that a Lorentz analysis of the cluster volume distribution is useful in characterizing cEOR displacement efficiency. Additionally, the fraction of smaller pores contributes to the additional oil recovery under optimal displacement conditions.
TRANSPORT IN POROUS MEDIA
(2023)
Article
Materials Science, Multidisciplinary
R. Nakamura, D. Takegami, A. Melendez-Sans, L. H. Tjeng, M. Okawa, T. Miyoshino, N. L. Saini, M. Kitamura, D. Shiga, H. Kumigashira, M. Yoshimura, K-D Tsuei, Y. Okamoto, T. Mizokawa
Summary: The electronic structure of CsW2O6 during its metal-insulator transition has been studied using hard/soft x-ray photoelectron spectroscopy. The transition is accompanied by the formation of a band gap attributed to the trimerization of W sites.
