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Wang X, Santos-Carballal D, de Leeuw NH. Cation doping and oxygen vacancies in the orthorhombic FeNbO4 material for solid oxide fuel cell applications: A density functional theory study. J Chem Phys 2024; 160:154713. [PMID: 38634493 DOI: 10.1063/5.0192749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 03/22/2024] [Indexed: 04/19/2024] Open
Abstract
The orthorhombic phase of FeNbO4, a promising anode material for solid oxide fuel cells (SOFCs), exhibits good catalytic activity toward hydrogen oxidation. However, the low electronic conductivity of the material specifically in the pure structure without defects or dopants limits its practical applications as an SOFC anode. In this study, we have employed density functional theory (DFT + U) calculations to explore the bulk and electronic properties of two types of doped structures, Fe0.9375A0.0625NbO4 and FeNb0.9375B0.0625O4 (A, B = Ti, V, Cr, Mn, Co, Ni) and the oxygen-deficient structures Fe0.9375A0.0625NbO3.9375 and FeNb0.9375B0.0625O3.9375, where the dopant is positioned in the first nearest neighbor site to the oxygen vacancy. Our DFT simulations have revealed that doping in the Fe sites is energetically favorable compared to doping in the Nb site, resulting in significant volume expansion. The doping process generally requires less energy when the O-vacancy is surrounded by one Fe and two Nb ions. The simulated projected density of states of the oxygen-deficient structures indicates that doping in the Fe site, particularly with Ti and V, considerably narrows the bandgap to ∼0.5 eV, whereas doping with Co at the Nb sites generates acceptor levels close to 0 eV. Both doping schemes, therefore, enhance electron conduction during SOFC operation.
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Affiliation(s)
- Xingyu Wang
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Nora H de Leeuw
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
- Department of Earth Sciences, Utrecht University, 3584 CB Utrecht, The Netherlands
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Zhang X, Huang Q. Toward Planar Iodine 2D Crystal Materials. ACS OMEGA 2021; 6:21235-21240. [PMID: 34471728 PMCID: PMC8387988 DOI: 10.1021/acsomega.1c00628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/14/2021] [Indexed: 06/13/2023]
Abstract
Usually, the octet rule determines whether an elemental 2D material can only be set by one of the elements in groups IIIA-VA, whose outmost electrons can form hybridized orbits from an s-wave and a p-wave. The hybridized orbits can accommodate all of the outermost electrons and form robust σ bonds. As for the elements in VIA-VIIA, the outermost electrons seem too abundant to be accommodated in hybridized orbits. Here, we show a spd2 hybridization rule, accommodating all of the outermost electrons of halogen elements. Each atom can be connected to a contiguous atom by a robust σ bond and carries one dangling unpaired electron, implying that the formation of a π bond is possible. One iodine atomic layer can be robustly locked by the σ bond, forming an iodiene sheet by spd2 hybridized orbits. With application of compression strain, the π bond forms, and further compression drives the band inversion successively at the valence band and the conduction band. The appearance of Dirac points (arc or hoop) suggests that the transformation of a normal semimetal into a Dirac semimetal occurs.
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Berry H, Wang B, Zhang Q. The Behavior of Magnetic Properties in the Clusters of 4d Transition Metals. Molecules 2018; 23:E1896. [PMID: 30060624 PMCID: PMC6222613 DOI: 10.3390/molecules23081896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 07/23/2018] [Accepted: 07/27/2018] [Indexed: 11/20/2022] Open
Abstract
The current focus of material science researchers is on the magnetic behavior of transition metal clusters due to its great hope for future technological applications. It is common knowledge that the 4d transition elements are not magnetic at their bulk size. However, studies indicate that their magnetic properties are strongly dependent on their cluster sizes. This study attempts to identify magnetic properties of 4d transition metal clusters. Using a tight-binding Friedel model for the density of d-electron states, we investigated the critical size for the magnetic-nonmagnetic transition of 4d transition-metal clusters. Approaching to the critical point, the density of states of the cluster near the Fermi level is higher than 1/J and the discrete energy levels form a quasi-continuous band. Where J is correlation integral. In order to determine the critical size, we considered a square shape band and fcc, bcc, icosahedral and cuboctahedral close-packed structures of the clusters. We also investigated this size dependent magnetic behavior using Heisenberg model. Taking some quantum mechanical approximations in to consideration, we determined magnetic behavior of the clusters. For practicality, we considered three clusters of transition metals (Ru, Rh and Pd) and the obtained results are in line with the results of previous studies.
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Affiliation(s)
- Habte Berry
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China.
- Department of Physics, College of Natural and Computational Sciences, Dilla University, P.O. Box 419, Dilla, Ethiopia.
| | - Baolin Wang
- School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, China.
| | - Qinfang Zhang
- School of Materials Science and Engineering, Yancheng Institute of Technology, Yancheng 224051, China.
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Alvarado-Leyva PG, Aguilera-Granja F, Balbás LC, Vega A. Antiferromagnetic-like coupling in the cationic iron cluster of thirteen atoms. Phys Chem Chem Phys 2013; 15:14458-64. [PMID: 23884079 DOI: 10.1039/c3cp51377g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We explore, within the density functional theory in the generalized gradient approximation to exchange and correlation, the map of spin isomers of the cationic Fe13(+) cluster in connection with recent X-ray magnetic circular dichroism spectroscopy experiments [M. Niemeyer et al., Phys. Rev. Lett. 2012, 108, 057201] which showed an anomalous low magnetic moment per number of 3d holes in this cluster. We systematically explore the low-lying magnetic excitations and correlate them with structural rearrangements and stability indicators. We obtain the observed low magnetic moment per 3d hole as the ground state of Fe13(+) and we demonstrate that, as supposed by the experimentalists, the cluster undergoes a magnetic transition from a ferromagnetic-like configuration to an antiferromagnetic-like one upon ionization. We unravel this unexpected magnetic behavior showing that it is concomitant with a Th-deformation of the icosahedral structure together with the electronic filling of this particular iron cluster. The spin-orbit interaction preserves this magnetic configuration which is essentially due to the spin. Our computed magnetic anisotropy energy supports the experimental interpretation of the cluster as fluxional due to the very weak coupling of the magnetic moment to an easy axis.
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Affiliation(s)
- P G Alvarado-Leyva
- Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, E-47011 Valladolid, Spain
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Faccin GM, da Silva EZ. Structure and Magnetism of Hybrid Fe and Co Nanoclusters up to N ≤ 7 Atoms. J CLUST SCI 2012. [DOI: 10.1007/s10876-012-0472-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Garibay-Alonso R, Reyes-Reyes M, Urrutia-Bañuelos E, López-Sandoval R. Calculation of spin and orbital magnetizations in Fe slab systems at finite temperature. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:056001. [PMID: 21386353 DOI: 10.1088/0953-8984/22/5/056001] [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 temperature dependence of spin and orbital local magnetizations is theoretically determined for the non-bulk atomic region of (001) and (110) Fe slab systems. A d band Hamiltonian, including spin-orbit coupling terms, was used to model the slabs, which were emulated by using Fe films of sufficient thickness to reach a bulk behavior at their most inner atomic layers. The temperature effects were considered within the static approximation and a simple mean field theory was used to integrate the local magnetic moment and charge thermal fluctuations. The results reflect a clear interplay between electronic itinerancy and the local atomic environment and they can be physically interpreted from the local small charge transfers occurring in the superficial region of the slabs. For recovering the experimental behavior on the results for the (001) slab system, the geometrical relaxations at its non-bulk atomic layers and a d band filling variation are required. A study on the magnetic anisotropy aspects in the superficial region of the slabs is additionally performed by analyzing the results for the orbital local magnetization calculated along two different magnetization directions in both slab systems.
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Affiliation(s)
- R Garibay-Alonso
- Facultad de Ciencias Físico Matemáticas, Universidad Autónoma de Coahuila, Conjunto Universitario Camporredondo, Edificio D, 25000 Saltillo, Mexico
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Zhang Z, Cao B, Duan H. Density-functional calculations of MnC(M=Fe, Co, Ni, Cu, n=1–6) clusters. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2008.05.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Density-functional theory has been used to determine the ground-state geometries and electronic states for homonuclear transition-metal trimers constrained to equilateral triangle geometries. This represents the first application of consistent theoretical methods to all of the ten 3d block transition-metal trimers, from scandium to zinc. A search of the potential surfaces yields the following electronic ground states and bond lengths: Sc3(2A1',2.83 A), Ti3(7E',2.32 A), V3(2E",2.06 A), Cr3(17E',2.92 A), Mn3(16A2',2.73 A), Fe3(11E",2.24 A), Co3(6E",2.18 A), Ni3(3A2",2.23 A), Cu3(2E',2.37 A), and Zn3(1A1',2.93 A). Vibrational frequencies, several low-lying electronic states, and trends in bond lengths and atomization energies are discussed. The predicted dissociation energies DeltaE(M3-->M2+M) are 49.4 kcal mol(-1)(Sc3), 64.3 kcal mol(-1)(Ti3), 60.7 kcal mol(-1)(V3), 11.5 kcal mol(-1)(Cr3), 32.4 kcal mol(-1)(Mn3), 61.5 kcal mol(-1)(Fe3), 78.0 kcal mol(-1)(Co3), 86.1 kcal mol(-1)(Ni3), 26.8 kcal mol(-1)(Cu3), and 4.5 kcal mol(-1)(Zn3).
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Affiliation(s)
- Brian N Papas
- Center for Computational Chemistry, University of Georgia, Athens, Georgia 30602, USA
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Noya EG, Longo RC, Gallego LJ. Density-functional calculations of the structures, binding energies, and spin multiplicities of Fe–C clusters. J Chem Phys 2003. [DOI: 10.1063/1.1622378] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Sljivancanin Z, Pasquarello A. Supported fe nanoclusters: evolution of magnetic properties with cluster size. PHYSICAL REVIEW LETTERS 2003; 90:247202. [PMID: 12857222 DOI: 10.1103/physrevlett.90.247202] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2002] [Indexed: 05/24/2023]
Abstract
Using a density functional approach, we study structural and magnetic properties of small Fe(n) clusters (n<or=8) deposited on a MgO(100) substrate. Upon deposition, the clusters closely preserve their gas-phase structure. The magnetic moments for the adsorbed clusters exceed the value for bulk Fe. Compared to the gas phase, significant reductions in the magnetic moments are found for Fe(n) clusters with n<or=6. These reductions result from intracluster charge rearrangements caused by interaction with O 2p orbitals, rather than from structural deformations or charge transfer from the surface. As the cluster size increases, the gas-phase magnetic moments are recovered.
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Affiliation(s)
- Z Sljivancanin
- Institut de Théorie des Phénomènes Physiques (ITP), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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Efremenko I. Implication of palladium geometric and electronic structures to hydrogen activation on bulk surfaces and clusters. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s1381-1169(01)00144-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Alonso JA. Electronic and atomic structure, and magnetism of transition-metal clusters. Chem Rev 2000; 100:637-78. [PMID: 11749247 DOI: 10.1021/cr980391o] [Citation(s) in RCA: 273] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J A Alonso
- Departamento de Física Teórica, Universidad de Valladolid, 47011 Valladolid, Spain
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Stepanyuk VS, Hergert W, Rennert P, Wildberger K, Zeller R, Dederichs PH. Magnetic dimers of transition-metal atoms on the Ag(001) surface. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:14121-14126. [PMID: 9985335 DOI: 10.1103/physrevb.54.14121] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Bouarab S, Vega A, Alonso JA, Iñiguez MP. Tight-binding study of the ionization of iron clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:3003-3006. [PMID: 9986185 DOI: 10.1103/physrevb.54.3003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Piveteau B, Desjonquères MC, Oles AM, Spanjaard D. Magnetic properties of 4d transition-metal clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:9251-9266. [PMID: 9982427 DOI: 10.1103/physrevb.53.9251] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Conceição J, Loh SK, Lian L, Armentrout PB. Guided ion beam studies of the reactions of Fe+n(n=2–15) with D2: Cluster–deuteride bond energies as a chemical probe of cluster structures. J Chem Phys 1996. [DOI: 10.1063/1.471253] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Bouarab S, Nait-Laziz H, Khan MA, Demangeat C, Dreyssé H, Benakki M. Spin polarization of Mn layers on Fe(001). PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:10127-10135. [PMID: 9980061 DOI: 10.1103/physrevb.52.10127] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Vega A, Demangeat C, Dreyssé H, Chouairi A. Possibility of various magnetic configurations in the Cr (Fe) monolayer deposited on vicinal surfaces of Fe (Cr). PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 51:11546-11554. [PMID: 9977888 DOI: 10.1103/physrevb.51.11546] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Zhao J, Chen X, Wang G. Critical size for a metal-nonmetal transition in transition-metal clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:15424-15426. [PMID: 9975901 DOI: 10.1103/physrevb.50.15424] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Vega A, Balbás LC, Dorantes-Dávila J, Pastor GM. Magnetic and electronic properties of substitutional FeN cluster impurities in Cr: Transition from antiferromagnetic to ferromagnetic FeN. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:3899-3906. [PMID: 9976668 DOI: 10.1103/physrevb.50.3899] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Alvarado P, Dorantes-Dávila J, Dreyssé H. Structural effects on the magnetism of small vanadium clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:1039-1045. [PMID: 9975771 DOI: 10.1103/physrevb.50.1039] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Lindgård PA, Hendriksen PV. Estimation of electronic and structural influence on the thermal magnetic properties of clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 49:12291-12294. [PMID: 10010112 DOI: 10.1103/physrevb.49.12291] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Vega A, Balbás LC, Nait-Laziz H, Demangeat C, Dreyssé H. Spin polarization at the Fe/V interface. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:985-992. [PMID: 10007957 DOI: 10.1103/physrevb.48.985] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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