1
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Rosenberg E, Bauer J, Cho E, Kumar A, Pelliciari J, Occhialini CA, Ning S, Kaczmarek A, Rosenberg R, Freeland JW, Chen YC, Wang JP, LeBeau J, Comin R, de Groot FMF, Ross CA. Revealing Site Occupancy in a Complex Oxide: Terbium Iron Garnet. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2300824. [PMID: 37060220 DOI: 10.1002/smll.202300824] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Indexed: 06/19/2023]
Abstract
Complex oxide films stabilized by epitaxial growth can exhibit large populations of point defects which have important effects on their properties. The site occupancy of pulsed laser-deposited epitaxial terbium iron garnet (TbIG) films with excess terbium (Tb) is analyzed, in which the terbium:iron (Tb:Fe)ratio is 0.86 compared to the stoichiometric value of 0.6. The magnetic properties of the TbIG are sensitive to site occupancy, exhibiting a higher compensation temperature (by 90 K) and a lower Curie temperature (by 40 K) than the bulk Tb3 Fe5 O12 garnet. Data derived from X-ray core-level spectroscopy, magnetometry, and molecular field coefficient modeling are consistent with occupancy of the dodecahedral sites by Tb3+ , the octahedral sites by Fe3+ , Tb3+ and vacancies, and the tetrahedral sites by Fe3+ and vacancies. Energy dispersive X-ray spectroscopy in a scanning transmission electron microscope provides direct evidence of TbFe antisites. A small fraction of Fe2+ is present, and oxygen vacancies are inferred to be present to maintain charge neutrality. Variation of the site occupancies provides a path to considerable manipulation of the magnetic properties of epitaxial iron garnet films and other complex oxides, which readily accommodate stoichiometries not found in their bulk counterparts.
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Affiliation(s)
- Ethan Rosenberg
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- 3M Corporate Research Materials Laboratory, 3M Center, St. Paul, MN, 55114, USA
| | - Jackson Bauer
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Eunsoo Cho
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Abinash Kumar
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Jonathan Pelliciari
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Connor A Occhialini
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
| | - Shuai Ning
- School of Materials Science and Engineering, Nankai University, Tianjin, 300350, P. R. China
| | - Allison Kaczmarek
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Richard Rosenberg
- Advanced Photon Source, X-Ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - John W Freeland
- Advanced Photon Source, X-Ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Yu-Chia Chen
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, 55455, USA
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, 55455, USA
| | - James LeBeau
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Riccardo Comin
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, United States
| | - F M F de Groot
- Materials Chemistry and Catalysis, Utrecht University, Universiteitslaan 99, Utrecht, 3584 CG, Netherlands
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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2
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Chen Y, Li Z, Ji N, Wei C, Duan X, Jiang H. The Local and Electronic Structure Study of Lu xGd 1-xVO 4 (0 ≤ x ≤ 1) Solid Solution Nanocrystals. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:323. [PMID: 36678077 PMCID: PMC9862454 DOI: 10.3390/nano13020323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Rare-earth-doped mixed crystals have demonstrated tunable optical properties, and it is of great importance to study the structural characteristics of the mixed-crystal hosts. Herein, LuxGd1-xVO4 (0 ≤ x ≤ 1) solid solution nanocrystals were synthesized by a modified sol-gel method, with a pure crystalline phase and element composition. The X-ray diffraction (XRD) and Rietveld refinement results showed that LuxGd1-xVO4 nanocrystals are continuous solid solutions with a tetragonal zircon phase (space group I41/amd) and the lattice parameters strictly follow Vegard's law. The detailed local structures were studied by extended X-ray absorption fine structure (EXAFS) spectra, which revealed that the average bond length of Gd-O fluctuates and decreases, while the average bond length of Lu-O gradually decreases with the increase in Lu content. Furthermore, the binding energy differences of core levels indicate that the covalent V-O bond is relatively stable, while the ionicity of the Lu-O bond decreases with the increasing x value, and the ionicity of the Gd-O bond fluctuates with small amplitude. The valence band structures were further confirmed by the first-principles calculations, indicating that the valence band is contributed to by the O 2p nonbonding state, localized Gd 4f and Lu 4f states, and the hybridized states between the bonding O 2p and V 3d. The binding energies of the Lu core and the valence levels tend to decrease gradually with the increase in Lu content. This work provides insight into the structural features of mixed-crystal hosts, which have been developed in recent years to improve laser performance by providing different positions for active ions to obtain inhomogeneous broadening spectra.
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Affiliation(s)
- Yang Chen
- State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
| | - Ziqing Li
- Institute of Optoelectronics, Fudan University, Shanghai 200433, China
| | - Nianjing Ji
- School of Materials Science & Engineering, Shandong Jianzhu University, Jinan 250101, China
| | - Chenxi Wei
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
| | - Xiulan Duan
- State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
| | - Huaidong Jiang
- State Key Laboratory of Crystal Materials, Institute of Crystal Materials, Shandong University, Jinan 250100, China
- Center for Transformative Science, ShanghaiTech University, Shanghai 201210, China
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3
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Li Y, Li T, Zhu X, Alshehri AA, Alzahrani KA, Lu S, Sun X. DyF
3
: An Efficient Electrocatalyst for N
2
Fixation to NH
3
under Ambient Conditions. Chem Asian J 2020; 15:487-489. [DOI: 10.1002/asia.201901624] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/25/2019] [Indexed: 01/02/2023]
Affiliation(s)
- Yuanfang Li
- School of Materials and EnergyUniversity of Electronic Science and Technology of China Chengdu 611731 Sichuan China
| | - Tingshuai Li
- School of Materials and EnergyUniversity of Electronic Science and Technology of China Chengdu 611731 Sichuan China
| | - Xiaojuan Zhu
- Institute of Fundamental and Frontier SciencesUniversity of Electronic Science and Technology of China Chengdu 610054 Sichuan China
| | - Abdulmohsen Ali Alshehri
- Chemistry DepartmentFaculty of ScienceKing Abdulaziz University P.O. Box 80203 Jeddah 21589 Saudi Arabia
| | - Khalid Ahmed Alzahrani
- Chemistry DepartmentFaculty of ScienceKing Abdulaziz University P.O. Box 80203 Jeddah 21589 Saudi Arabia
| | - Siyu Lu
- Green Catalysis Center and College of ChemistryZhengzhou University Zhengzhou 450001 Henan China
| | - Xuping Sun
- Institute of Fundamental and Frontier SciencesUniversity of Electronic Science and Technology of China Chengdu 610054 Sichuan China
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4
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Jannsen N, Diodati S, Dengo N, Tajoli F, Vicentini N, Lucchini G, Speghini A, Badocco D, Pastore P, Gross S. Exploring the Phase‐Selective, Green, Hydrothermal Synthesis of Upconverting Doped Sodium Yttrium Fluoride: Effects of Temperature, Time, and Precursors. Chemistry 2019; 25:13624-13634. [DOI: 10.1002/chem.201903261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Nora Jannsen
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- Institute of Inorganic and Applied ChemistryUniversity of Hamburg 20146 Hamburg Germany
| | - Stefano Diodati
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- INSTM, UdR di Padova Via Marzolo 1 35131 Padova Italy
| | - Nicola Dengo
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- INSTM, UdR di Padova Via Marzolo 1 35131 Padova Italy
| | - Francesca Tajoli
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- INSTM, UdR di Padova Via Marzolo 1 35131 Padova Italy
| | - Nicola Vicentini
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- INSTM, UdR di Padova Via Marzolo 1 35131 Padova Italy
| | - Giacomo Lucchini
- NRG, Dipartimento of BiotecnologieUniversità di Verona and INSTM, RU Verona Strada Le Grazie 15 37314 Verona Italy
| | - Adolfo Speghini
- NRG, Dipartimento of BiotecnologieUniversità di Verona and INSTM, RU Verona Strada Le Grazie 15 37314 Verona Italy
| | - Denis Badocco
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
| | - Paolo Pastore
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
| | - Silvia Gross
- Dipartimento di Scienze ChimicheUniversità degli Studi di Padova Via Marzolo 1 35131 Padova Italy
- INSTM, UdR di Padova Via Marzolo 1 35131 Padova Italy
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5
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Barry K, Zhang B, Anand N, Xin Y, Vailionis A, Neu J, Heikes C, Cochran C, Zhou H, Qiu Y, Ratcliff W, Siegrist T, Beekman C. Modification of spin-ice physics in Ho2Ti2O7 thin films. PHYSICAL REVIEW MATERIALS 2019; 3:10.1103/physrevmaterials.3.084412. [PMID: 38617995 PMCID: PMC11015469 DOI: 10.1103/physrevmaterials.3.084412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
We present an extensive study on the effect of substrate orientation, strain, stoichiometry, and defects on spin-ice physics in Ho 2 Ti 2 O 7 thin films grown onto yttria-stabilized-zirconia substrates. We find that growth in different orientations produces different strain states in the films. All films exhibit similar c -axis lattice parameters for their relaxed portions, which are consistently larger than the bulk value of 10.1 Å. Transmission electron microscopy reveals antisite disorder and growth defects to be present in the films, but evidence of stuffing is not observed. The amount of disorder depends on the growth orientation, with the (110) film showing the least. Magnetization measurements at 1.8 K show the expected magnetic anisotropy and saturation magnetization values associated with a spin ice for all orientations; shape anisotropy is apparent when comparing in- and out-of-plane directions. Significantly, only the (110)-oriented films display the hallmark spin-ice plateau state in magnetization, albeit less well defined compared to the plateau observed in a single crystal. Neutron-scattering maps on the more disordered (111)-oriented films show the Q = 0 phase previously observed in bulk materials, but the Q = X phase giving the plateau state remains elusive. We conclude that the spin-ice physics in thin films is modified by defects and strain, leading to a reduction in the temperature at which correlations drive the system into the spin-ice state.
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Affiliation(s)
- Kevin Barry
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Biwen Zhang
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Naween Anand
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Yan Xin
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Arturas Vailionis
- Stanford Nano Shared Facilities, Stanford University, Stanford, California 94305, USA
| | - Jennifer Neu
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Colin Heikes
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Charis Cochran
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Haidong Zhou
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
- Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Y. Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - William Ratcliff
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - Theo Siegrist
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310, USA
| | - Christianne Beekman
- Department of Physics, Florida State University, Tallahassee, Florida 32310, USA
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
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6
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Kaminaga K, Oka D, Hasegawa T, Fukumura T. New Lutetium Oxide: Electrically Conducting Rock-Salt LuO Epitaxial Thin Film. ACS OMEGA 2018; 3:12501-12504. [PMID: 31457982 PMCID: PMC6644888 DOI: 10.1021/acsomega.8b02082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 09/19/2018] [Indexed: 06/10/2023]
Abstract
C-rare earth structure lutetium sesquioxide Lu2O3 has been recognized as a high-k widegap insulator with closed shell Lu3+ ions. In this study, rock-salt structure lutetium monoxide LuO with unusual valence of Lu2+ (4f145d1), previously known as the gaseous phase, was synthesized as an epitaxial thin film by the pulsed laser deposition method. In contrast with transparent and highly insulating Lu2O3, LuO possessed a dark-brown color and high electrical conductivity concomitant with strong spin-orbit coupling as a manifestation of Lu 5d electron carriers.
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Affiliation(s)
- Kenichi Kaminaga
- Department
of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
- WPI-Advanced Institute for Materials
Research and Core Research Cluster, and Center for Spintronics
Research Network, Tohoku University, Sendai 980-8577, Japan
| | - Daichi Oka
- Department
of Chemistry, Tohoku University, Sendai 980-8578, Japan
| | - Tetsuya Hasegawa
- Department
of Chemistry, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tomoteru Fukumura
- WPI-Advanced Institute for Materials
Research and Core Research Cluster, and Center for Spintronics
Research Network, Tohoku University, Sendai 980-8577, Japan
- Department
of Chemistry, Tohoku University, Sendai 980-8578, Japan
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7
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Berger CA, Arkhipova M, Maas G, Jacob T. Dysprosium electrodeposition from a hexaalkylguanidinium-based ionic liquid. NANOSCALE 2016; 8:13997-14003. [PMID: 27121463 DOI: 10.1039/c6nr01351a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The rare-earth element dysprosium (Dy) is an important additive that increases the magnetocrystalline anisotropy of neodymium magnets and additionally prevents from demagnetizing at high temperatures. Therefore, it is one of the most important elements for high-tech industries and is mainly used in permanent magnetic applications, for example in electric vehicles, industrial motors and direct-drive wind turbines. In an effort to develop a more efficient electrochemical technique for depositing Dy on Nd-magnets in contrast to commonly used costly physical vapor deposition, we investigated the electrochemical behavior of dysprosium(iii) trifluoromethanesulfonate in a custom-made guanidinium-based room-temperature ionic liquid (RTIL). We first examined the electrodeposition of Dy on an Au(111) model electrode. The investigation was carried out by means of cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS). The initial stages of metal deposition were followed by in situ scanning tunneling microscopy (STM). CV measurements revealed a large cathodic reduction peak, which corresponds to the growth of monoatomic high islands, based on STM images taken during the initial stages of deposition. XPS identified these deposited islands as dysprosium. A similar reduction peak was also observed on an Nd-Fe-B substrate, and positively identified as deposited Dy using XPS. Finally, we varied the concentration of the Dy precursor, electrolyte flow and temperature during Dy deposition and demonstrated that each of these parameters could be used to increase the thickness of the Dy deposit, suggesting that these parameters could be tuned simultaneously in a temperature-controlled flow cell to enhance the thickness of the Dy layer.
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Affiliation(s)
- Claudia A Berger
- Institute of Electrochemistry, Ulm University, Albert-Einstein-Allee 47, 89081 Ulm, Germany.
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8
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Naderi HR, Ganjali MR, Dezfuli AS, Norouzi P. Sonochemical preparation of a ytterbium oxide/reduced graphene oxide nanocomposite for supercapacitors with enhanced capacitive performance. RSC Adv 2016. [DOI: 10.1039/c6ra02943d] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Decoration of graphene with different nanostructures can result in fundamental advancements in versatile technologies, especially in the fast growing fields of catalysts, sensors and energy storage.
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Affiliation(s)
- Hamid Reza Naderi
- Center of Excellence in Electrochemistry
- Faculty of Chemistry
- University of Tehran
- Tehran
- Iran
| | - Mohammad Reza Ganjali
- Center of Excellence in Electrochemistry
- Faculty of Chemistry
- University of Tehran
- Tehran
- Iran
| | | | - Parviz Norouzi
- Center of Excellence in Electrochemistry
- Faculty of Chemistry
- University of Tehran
- Tehran
- Iran
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9
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Hsu HL, Leong KR, Teng IJ, Halamicek M, Juang JY, Jian SR, Qian L, Kherani NP. Reduction of Photoluminescence Quenching by Deuteration of Ytterbium-Doped Amorphous Carbon-Based Photonic Materials. MATERIALS 2014; 7:5643-5663. [PMID: 28788152 PMCID: PMC5456179 DOI: 10.3390/ma7085643] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/21/2014] [Accepted: 07/31/2014] [Indexed: 01/17/2023]
Abstract
In situ Yb-doped amorphous carbon thin films were grown on Si substrates at low temperatures (<200 °C) by a simple one-step RF-PEMOCVD system as a potential photonic material for direct integration with Si CMOS back end-of-line processing. Room temperature photoluminescence around 1 µm was observed via direct incorporation of optically active Yb3+ ions from the selected Yb(fod)₃ metal-organic compound. The partially fluorinated Yb(fod)₃ compound assists the suppression of photoluminescence quenching by substitution of C-H with C-F bonds. A four-fold enhancement of Yb photoluminescence was demonstrated via deuteration of the a-C host. The substrate temperature greatly influences the relative deposition rate of the plasma dissociated metal-organic species, and hence the concentration of the various elements. Yb and F incorporation are promoted at lower substrate temperatures, and suppressed at higher substrate temperatures. O concentration is slightly elevated at higher substrate temperatures. Photoluminescence was limited by the concentration of Yb within the film, the concentration of Yb ions in the +3 state, and the relative amount of quenching due to the various de-excitation pathways associated with the vibrational modes of the host a-C network. The observed wide full-width-at-half-maximum photoluminescence signal is a result of the variety of local bonding environments due to the a-C matrix, and the bonding of the Yb3+ ions to O and/or F ions as observed in the X-ray photoelectron spectroscopy analyses.
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Affiliation(s)
- Hui-Lin Hsu
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
| | - Keith R Leong
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
| | - I-Ju Teng
- Center for Interdisciplinary Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84001, Taiwan.
| | - Michael Halamicek
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
| | - Jenh-Yih Juang
- Center for Interdisciplinary Science, National Chiao Tung University, Hsinchu 30010, Taiwan.
| | - Sheng-Rui Jian
- Department of Materials Science and Engineering, I-Shou University, Kaohsiung 84001, Taiwan.
| | - Li Qian
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
| | - Nazir P Kherani
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada.
- Department of Materials Science and Engineering, University of Toronto, Toronto, ON M5S 3E4, Canada.
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10
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Miyazaki T, Tokumoto Y, Sumii R, Yagi H, Izumi N, Shinohara H, Hino S. Photoelectron spectra of thulium atoms encapsulated C82 fullerene, Tm2@C82 (III) and Tm2C2@C82 (III). Chem Phys 2014. [DOI: 10.1016/j.chemphys.2014.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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11
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Bisti F, Stroppa A, Donarelli M, Anemone G, Perrozzi F, Picozzi S, Ottaviano L. Unravelling the role of the central metal ion in the electronic structure of tris(8-hydroxyquinoline) metal chelates: photoemission spectroscopy and hybrid functional calculations. J Phys Chem A 2012; 116:11548-52. [PMID: 23106099 DOI: 10.1021/jp308303d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic structures of tris(8-hydroxyquinolinato)-erbium(III) (ErQ(3)) and tris(8-hydroxyquinolinato)-aluminum(III) (AlQ(3)) have been studied by means of core level and valence band photoemission spectroscopy with the theoretical support of hybrid Heyd-Scuseria-Ernzerhof density functional theory, to investigate the role played by the central metal atom. A lower binding energy (0.2 eV and 0.3 eV, respectively) of the O 1s and N 1s core levels has been observed for ErQ(3) with respect to AlQ(3). Differences in the valence band spectra, mainly related to the first two peaks next to the highest occupied molecular orbital (HOMO), have been ascribed to an energetic shift (to 0.4 eV lower energies for ErQ(3)) of the σ molecular orbital between the oxygen atoms and the central metal atom. A lower (by 0.5 eV) ionization energy has been measured for the ErQ(3). The interpretation of these results is based on a reduced interaction between the central metal atom and the ligands in ErQ(3), with increased electronic charge around the ligands, due to the higher ionic radius and the lower electronegativity of Er with respect to Al.
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Affiliation(s)
- F Bisti
- Dipartimento di Scienze Fisiche e Chimiche, Università dell'Aquila, Via Vetoio, 67100 L'Aquila, Italy.
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12
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Pasquali L, Montecchi M, Nannarone S, Boscherini F. Atomic and electronic structure of ultrathin fluoride barrier layers at the oxide/Si interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:355003. [PMID: 21785187 DOI: 10.1088/0953-8984/23/35/355003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A SrF(2) ultrathin barrier layer on Si(001) is used to form a sharp interface and block reactivity and intermixing between the semiconductor and a Yb(2)O(3) overlayer. Yb(2)O(3)/Si(001) and Yb(2)O(3)/SrF(2)/Si(001) interfaces grown in ultra high vacuum by molecular beam epitaxy are studied by photoemission and x-ray absorption fine structure. Without the fluoride interlayer, Yb(2)O(3)/Si(001) presents an interface reacted region formed by SiO(x) and/or silicate compounds, which is about 9 Å thick and increases up to 14-15 Å after annealing at 500-700 °C. A uniform single layer of SrF(2) molecules blocks intermixing and reduces the oxidized Si region to 2.4 Å after deposition and to 3.5 Å after annealing at 500 °C. In both cases we estimate a conduction band offset and a valence band offset of ∼ 1.7 eV and 2.4 eV between the oxide and Si, respectively. X-ray absorption fine structure measurements at the Yb L(III) edge suggest that the Yb oxide films exhibit a significant degree of static disorder with and without the fluoride barrier. Sr K edge measurements indicate that the ultrathin fluoride films are reacted, with the formation of bonds between Si and Sr; the Sr-Sr and Sr-F interatomic distances in the ultrathin fluoride barrier film are relaxed to the bulk value.
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Affiliation(s)
- L Pasquali
- Department of Materials and Environmental Engineering, University of Modena and Reggio Emilia, Via Vignolese 905, I-41125 Modena, Italy
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13
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Milanov AP, Seidel RW, Barreca D, Gasparotto A, Winter M, Feydt J, Irsen S, Becker HW, Devi A. Malonate complexes of dysprosium: synthesis, characterization and application for LI-MOCVD of dysprosium containing thin films. Dalton Trans 2011; 40:62-78. [DOI: 10.1039/c0dt00455c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Yamasaki A, Imada S, Higashimichi H, Fujiwara H, Saita T, Miyamachi T, Sekiyama A, Sugawara H, Kikuchi D, Sato H, Higashiya A, Yabashi M, Tamasaku K, Miwa D, Ishikawa T, Suga S. Coexistence of strongly mixed-valence and heavy-fermion character in SmOs4Sb12 studied by soft- and hard-X-ray spectroscopy. PHYSICAL REVIEW LETTERS 2007; 98:156402. [PMID: 17501367 DOI: 10.1103/physrevlett.98.156402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Indexed: 05/15/2023]
Abstract
Sm-based heavy-fermion compound SmOs4Sb12 has been investigated by soft x-ray (hnu=1070-1600 eV) and hard x-ray (HX; hnu=7932 eV) spectroscopy. The HX photoemission spectroscopy clearly demonstrates that the strongly mixed-valence state and the heavy-fermion state coexist in the bulk. It is found that the Sm valence decreases below 100 K, indicating that the Kondo coherence develops with approaching the proposed Kondo temperature. Our theoretical analyses suggest that the origin of the coexistence in SmOs4Sb12 is the coincidence of two conditions, namely, (i) the energy difference between Sm divalent and trivalent states is very small and (ii) the hybridization between Sm 4f and conduction electrons is weak.
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Affiliation(s)
- A Yamasaki
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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Szytuła A, Jezierski A, Winiarski A, Penc B, Tran VH. Photoemission studies and electronic structure of U(2)T(2)In (T = Ni, Rh, Pt) compounds. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:4355-4370. [PMID: 21690787 DOI: 10.1088/0953-8984/18/17/021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The electronic structure of the tetragonal U(2)T(2)In (T = Ni, Rh, Pt) compounds in the paramagnetic phase were studied by x-ray photoelectron spectroscopy (XPS). Both valence band and core level spectra were analysed. The experimental data are compared with the calculations of the density of states using the tight-binding linear muffin-tin orbital method (TB-LMTO) and full-potential local-orbital full-relativistic method (FPLO). The calculated data reveal a dominant U 5f electron character for the states near the Fermi level E(F) with a small contribution from U 5d, Ni 3d, Rh 4d, Pt 5d and In 5p states. The XPS valence bands of these compounds are characterized by a sharp peak of the U 5f states near the Fermi level (E(F)) and broad peaks of the Ni 3d, Rh 4d and Pt 5d states at about 2.6, 3.2 and 4.0 eV below E(F), respectively. The small change in the position of the U 5f peak with respect to E(F) is -0.35 eV for T = Ni and -0.15 eV for T = Rh and Pt. A satellite between the Ni 2p(1/2) and Ni 2p(3/2) peaks is visible, suggesting that the Ni 3d band is not completely filled, and the existence of a small induced magnetic moment on the Ni atoms cannot be ruled out.
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Affiliation(s)
- A Szytuła
- M Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland
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Lademan WJ, See AK, Klebanoff LE. Multiplet structure in high-resolution and spin-resolved x-ray photoemission from gadolinium. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:17191-17198. [PMID: 9985855 DOI: 10.1103/physrevb.54.17191] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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17
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Arenholz E, Navas E, Bauer A, Kaindl G. Magnetic circular dichroism and orbital momentum coupling in 4d photoemission from Gd(0001). PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:R5998-R6001. [PMID: 9982095 DOI: 10.1103/physrevb.53.r5998] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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18
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Castrucci P, Yubero F, Vicentin FC, Vogel J, Sacchi M. Surface crystal field at the Er/Si(111) interface studied by soft-x-ray linear dichroism. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:14035-14039. [PMID: 9980620 DOI: 10.1103/physrevb.52.14035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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