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Sakhraoui T, Karlický F. Prediction of induced magnetism in 2D Ti 2C based MXenes by manipulating the mixed surface functionalization and metal substitution computed by xTB model Hamiltonian of the DFTB method. Phys Chem Chem Phys 2024; 26:12862-12868. [PMID: 38623885 DOI: 10.1039/d3cp05665a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
We employed the recently developed density functional tight binding (DFTB) method's Hamiltonian, GFN1-xTB, for modeling the mixed termination in Ti2C MXenes, namely three types of termination by combining -O and -OH, -O and -F, and -F and -OH. We demonstrated that the approach yields reliable predictions for the electronic and magnetic properties of such MXenes. The first highlighted result is that the mixed surface functionalization in Ti2CAxBy MXenes induces spin polarization with diverse magnetic alignments, including ferromagnetism and two types of antiferromagnetism. We further identified the magnetic alignment for the investigated MXene in terms of the compositions of the terminal groups. Moreover, the effect of the transition metal (Ti) substituted by the Sc atom on the electronic and magnetic properties was also investigated. We found that the studied systems maintain the magnetism and the metallic characteristics. A magnetic transition from antiferromagnetic (AFM) to ferrimagnetic (FiM) ordering was found for ScTi15C8F8(OH)8 and ScTi15C8F12(OH)4 compounds. Finally, we proved that incorporating the Sc atom into the lattice of Ti2CO2 and the mixed surface termination in Ti2CAxBy is an effective strategy to induce magnetism. Our study may provide a new potential application for designing MXene-based spintronics.
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Affiliation(s)
- Taoufik Sakhraoui
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
| | - František Karlický
- Department of Physics, Faculty of Science, University of Ostrava, 701 03 Ostrava, Czech Republic.
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García-Romeral N, Keyhanian M, Morales-García Á, Viñes F, Illas F. Understanding the Chemical Bond in Semiconductor/MXene Composites: TiO 2 Clusters Anchored on the Ti 2C MXene Surface. Chemistry 2024; 30:e202400255. [PMID: 38251957 DOI: 10.1002/chem.202400255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Accepted: 01/22/2024] [Indexed: 01/23/2024]
Abstract
First-principles calculations on titania clusters (TiO2)n (n=5 and 10) supported on the pristine Ti2C (0001) surface were carried out to understand the properties of semiconductor/MXene composites with implications in (photo)-catalysis. The reported results reveal a high exothermic interaction accompanied by a substantial charge transfer with a concomitant, notorious, deformation of the titania nanoclusters. The analysis of the density of states analysis of the composite systems evidences a metallic character with titania related states crossing the Fermi level. The picture of the chemical bonds is completed by the analysis of X-Ray Photoelectron Spectra (XPS) features, evidencing clear shifts of the C(1s) and O(1s) related peaks relative to the isolated systems that have a quite complex origin. This detailed analysis provides insights to experimentalists interested in the design and synthesis of these systems with possible applications in catalysis.
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Affiliation(s)
- Néstor García-Romeral
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1-11, 08028, Barcelona, Spain
| | - Masoomeh Keyhanian
- Department of Physical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, 47416-95447, Iran
| | - Ángel Morales-García
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1-11, 08028, Barcelona, Spain
| | - Francesc Viñes
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1-11, 08028, Barcelona, Spain
| | - Francesc Illas
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/ Martí i Franquès 1-11, 08028, Barcelona, Spain
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Yang J, Shi F, Zhao H, Chen L. Changing the spin disorder of two-dimensional magnetic Cr 2TiC 2T x to long-range order through noble metal adhesion. iScience 2024; 27:109227. [PMID: 38433897 PMCID: PMC10904981 DOI: 10.1016/j.isci.2024.109227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/08/2023] [Accepted: 02/08/2024] [Indexed: 03/05/2024] Open
Abstract
To enhance the use of Cr2TiC2Tx MXene in spin electronics, it is essential to transform its spin-disordered state into a long-range ordered spin state. In this study, first-principles calculations show that Rh layers adhered to the Cr2TiC2Tx surfaces can transform its spin disordered state into a long-range spin order by donating electrons to the O terminations, resulting in Cr2TiC2Tx becoming a single-layer A-type antiferromagnet. As the proportion of F termination increases from 0 to 100%, the exchange coupling constant J1 of the compound escalates from 0.5 to 15.9 meV. Concurrently, the Néel temperature experiences a significant rise from 8 K to 110 K. The analysis of the density of states reveals that the obtained Cr2TiC2Tx exhibits excellent conductivity with O termination and semiconductor characteristics with F termination. These unique features make Cr2TiC2Tx a promising magnetic material for application in spin electronics.
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Affiliation(s)
- Jianhui Yang
- Quzhou University, Quzhou 324000, P.R. China
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, P.R. China
| | - Fei Shi
- Quzhou University, Quzhou 324000, P.R. China
| | | | - Liang Chen
- Key Laboratory of Advanced Fuel Cells and Electrolyzers Technology of Zhejiang Province, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, P.R. China
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García-Romeral N, Morales-García Á, Viñes F, de P R Moreira I, Illas F. The nature of the electronic ground state of M 2C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes. Phys Chem Chem Phys 2023; 25:31153-31164. [PMID: 37953662 DOI: 10.1039/d3cp04402e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2023]
Abstract
A systematic computational study is presented aimed at accurately describing the electronic ground state nature and properties of M2C (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) MXenes. Electronic band structure calculations in the framework of density functional theory (DFT), carried out with different types of basis sets and employing the generalized gradient approach (GGA) and hybrid functionals, provide strong evidence that Ti2C, Zr2C, Hf2C, and Cr2C MXenes exhibit an open-shell conducting ground state with localized spins on the metal atoms, while V2C, Nb2C, Mo2C, Ta2C, and W2C MXenes exhibit a diamagnetic conducting ground state. For Ti2C, Zr2C, Hf2C, and Cr2C, the analysis of the low-lying spin polarized solutions with different spin orderings indicates that their ground states are antiferromagnetic (AFM), consisting of two ferromagnetic (FM) metal layers coupled antiferromagnetically. For the diamagnetic MXenes, the converged spin polarized solutions are significantly less stable than the closed shell solution except for the case of V2C and Mo2C where those excited open shell solutions can be thermally accessible (less than 300 meV per formula unit). The analysis of charge and spin density distributions of the ground state of the MXenes reveals that, in all cases, the metal atoms have a net charge close to +1 e and C atoms close to -2 e. In the case of diamagnetic MXenes, the electronic structure of V2C, Nb2C, and Ta2C is consistent with metal atoms exhibiting a closed-shell s2d2 configuration whereas for Mo2C, and W2C is consistent with a low-spin s1d4 configuration although the FM solution is close in energy for V2C and Mo2C suggesting that they may play a role in their chemistry at high temperature. For the open shell MXenes, the spin density primarily located at the metal atoms showing one unpaired electron per Ti+, Zr+, and Hf+ magnetic center, consistent with s2d1 configuration of the metal atom, and of ∼3.5 unpaired electrons per Cr+ magnetic center interpreted as a mixture of s2d3 and high-spin s1d4 configuration. Finally, the analysis of the density of states reveals the metallic character of all these bare MXenes, irrespective of the nature of the ground state, with significant covalent contributions for Mo2C and W2C.
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Affiliation(s)
- Néstor García-Romeral
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
| | - Ángel Morales-García
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
| | - Francesc Viñes
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
| | - Ibério de P R Moreira
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
| | - Francesc Illas
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1, 08028 Barcelona, Spain.
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García-Romeral N, Morales-García Á, Viñes F, Moreira IDPR, Illas F. How does thickness affect magnetic coupling in Ti-based MXenes. Phys Chem Chem Phys 2023. [PMID: 37357567 DOI: 10.1039/d3cp01617j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
Abstract
The magnetic nature of Ti2C, Ti3C2, and Ti4C3 MXenes is determined from periodic calculations within density functional theory and using the generalized gradient approximation based PBE functional, the PBE0 and HSE06 hybrids, and the on-site Hubbard corrected PBE+U one, in all cases using a very tight numerical setup. The results show that all functionals consistently predict a magnetic ground state for all MXenes, with spin densities mainly located at the Ti surface atoms. The analysis of solutions corresponding to different spin orderings consistently show that all functionals predict an antiferromagnetic conducting ground state with the two ferromagnetic outer (surface) Ti layers being antiferromagnetically coupled. A physically meaningful spin model is proposed, consistent with the analysis of the chemical bond, with closed shell, diamagnetic, Ti2+ like ions in inner layers and surface paramagnetic Ti+ like centers with one unpaired electron per magnetic center. From a Heisenberg spin model, the relevant isotropic magnetic coupling constants are extracted from an appropriate mapping of total energy differences per formula unit to the expected energy values of the spin Hamiltonian. While the numerical values of the magnetic coupling constants largely depend on the used functional, the nearest neighbor intralayer coupling is found to be always ferromagnetic, and constitutes the dominant interaction, although two other non-negligible interlayer antiferromagnetic terms are involved, implying that the spin description cannot be reduced to NN interaction only. The influence of the MXene thickness is noticeable for the dominant ferromagnetic interaction, increasing its value with the MXene width. However, the interlayer interactions are essentially due to the covalency effects observed in all metallic solutions which, as expected, decay with distance. Within the PBE+U approach, a U value of 5 eV is found to closely simulate the results from hybrid functionals for Ti2C and less accurately for Ti3C2 and Ti4C3.
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Affiliation(s)
- Néstor García-Romeral
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, 08028 Barcelona, Spain.
| | - Ángel Morales-García
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, 08028 Barcelona, Spain.
| | - Francesc Viñes
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, 08028 Barcelona, Spain.
| | - Ibério de P R Moreira
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, 08028 Barcelona, Spain.
| | - Francesc Illas
- Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, c/Martí i Franquès 1-11, 08028 Barcelona, Spain.
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Özcan S, Biel B. MXene-based Ti 2C/Ta 2C lateral heterostructure: an intrinsic room temperature ferromagnetic material with large magnetic anisotropy. RSC Adv 2023; 13:17222-17229. [PMID: 37304787 PMCID: PMC10248545 DOI: 10.1039/d3ra03343k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 05/30/2023] [Indexed: 06/13/2023] Open
Abstract
Two-dimensional (2D) lateral heterostructures (LH) combining Ti2C and Ta2C MXenes were investigated by means of first-principles calculations. Our structural and elastic properties calculations show that the lateral Ti2C/Ta2C heterostructure results in a 2D material that is stronger than the original isolated MXenes and other 2D monolayers such as germanene or MoS2. The analysis of the evolution of the charge distribution with the size of the LH shows that, for small systems, it tends to distribute homogeneously between the two monolayers, whereas for larger systems electrons tend to accumulate in a region of ∼6 Å around the interface. The work function of the heterostructure, one crucial parameter in the design of electronic nanodevices, is found to be lower than that of some conventional 2D LH. Remarkably, all the heterostructures studied show a very high Curie temperature (between 696 K and 1082 K), high magnetic moments and high magnetic anisotropy energies. These features make (Ti2C)/(Ta2C) lateral heterostructures very suitable candidates for spintronic, photocatalysis, and data storage applications based upon 2D magnetic materials.
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Affiliation(s)
- S Özcan
- Department of Physics, Aksaray University 68100 Aksaray Turkey
| | - B Biel
- Department of Atomic, Molecular and Nuclear Physics, Instituto Carlos I de Física Teórica y Computacional, Faculty of Science, Campus de Fuente Nueva, University of Granada 18071 Granada Spain
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