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Schaack S, Mangaud E, Fallacara E, Huppert S, Depondt P, Finocchi F. When Quantum Fluctuations Meet Structural Instabilities: The Isotope- and Pressure-Induced Phase Transition in the Quantum Paraelectric NaOH. PHYSICAL REVIEW LETTERS 2023; 131:126101. [PMID: 37802932 DOI: 10.1103/physrevlett.131.126101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/17/2023] [Accepted: 08/15/2023] [Indexed: 10/08/2023]
Abstract
Anhydrous sodium hydroxide, a common and structurally simple compound, shows spectacular isotope effects: NaOD undergoes a first-order transition, which is absent in NaOH. By combining ab initio electronic structure calculations with Feynman path integrals, we show that NaOH is an unusual example of a quantum paraelectric: zero-point quantum fluctuations stretch the weak hydrogen bonds (HBs) into a region where they are unstable and break. By strengthening the HBs via isotope substitution or applied pressure, the system can be driven to a broken-symmetry antiferroelectric phase. In passing, we provide a simple quantitative criterion for HB breaking in layered crystals and show that nuclear quantum effects are crucial in paraelectric to ferroelectric transitions in hydrogen-bonded hydroxides.
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Affiliation(s)
- Sofiane Schaack
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Etienne Mangaud
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
- Univ Gustave Eiffel, Univ Paris Est Creteil, CNRS, UMR 8208, MSME, F-77454 Marne-la-Vallée, France
| | - Erika Fallacara
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Simon Huppert
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Philippe Depondt
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Fabio Finocchi
- Sorbonne Université, CNRS UMR 7588, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
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Cantos-Prieto F, Falin A, Alliati M, Qian D, Zhang R, Tao T, Barnett MR, Santos EJG, Li LH, Navarro-Moratalla E. Layer-Dependent Mechanical Properties and Enhanced Plasticity in the Van der Waals Chromium Trihalide Magnets. NANO LETTERS 2021; 21:3379-3385. [PMID: 33835813 PMCID: PMC8454994 DOI: 10.1021/acs.nanolett.0c04794] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/29/2021] [Indexed: 05/30/2023]
Abstract
The mechanical properties of magnetic materials are instrumental for the development of magnetoelastic theories and the optimization of strain-modulated magnetic devices. In particular, two-dimensional (2D) magnets hold promise to enlarge these concepts into the realm of low-dimensional physics and ultrathin devices. However, no experimental study on the intrinsic mechanical properties of the archetypal 2D magnet family of the chromium trihalides has thus far been performed. Here, we report the room temperature layer-dependent mechanical properties of atomically thin CrCl3 and CrI3, finding that the bilayers have Young's moduli of 62.1 and 43.4 GPa, highest sustained strains of 6.49% and 6.09% and breaking strengths of 3.6 and 2.2 GPa, respectively. This portrays the outstanding plasticity of these materials that is qualitatively demonstrated in the bulk crystals. The current study will contribute to the applications of the 2D magnets in magnetostrictive and flexible devices.
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Affiliation(s)
- Fernando Cantos-Prieto
- Instituto
de Ciencia Molecular, Universitat de València, Calle Catedrático José
Beltrán Martínez 2, 46980, Paterna, Spain
| | - Alexey Falin
- Guangdong
Provincial Key Laboratory of Functional Soft Condensed Matter, School
of Materials and Energy, Guangdong University
of Technology, Guangzhou 510006, China
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Martin Alliati
- School
of Mathematics and Physics, Queen’s
University Belfast, BT7 1NN Belfast, United Kingdom
| | - Dong Qian
- Department
of Mechanical Engineering, The University
of Texas at Dallas, Richardson, Texas 75080, United States
| | - Rui Zhang
- Department
of Mechanical Engineering, The University
of Texas at Dallas, Richardson, Texas 75080, United States
| | - Tao Tao
- Guangdong
Provincial Key Laboratory of Functional Soft Condensed Matter, School
of Materials and Energy, Guangdong University
of Technology, Guangzhou 510006, China
| | - Matthew R. Barnett
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Elton J. G. Santos
- Institute
for Condensed Matter Physics and Complex Systems, School of Physics
and Astronomy, The University of Edinburgh, EH9 3FD Edinburgh, United Kingdom
- Higgs
Centre for Theoretical Physics, The University
of Edinburgh, EH9 3FD Edinburgh, U.K.
| | - Lu Hua Li
- Institute
for Frontier Materials, Deakin University, Geelong Waurn Ponds Campus, Waurn Ponds, Victoria 3216, Australia
| | - Efrén Navarro-Moratalla
- Instituto
de Ciencia Molecular, Universitat de València, Calle Catedrático José
Beltrán Martínez 2, 46980, Paterna, Spain
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Torres-Sánchez A, Vanegas JM, Arroyo M. Examining the Mechanical Equilibrium of Microscopic Stresses in Molecular Simulations. PHYSICAL REVIEW LETTERS 2015; 114:258102. [PMID: 26197144 DOI: 10.1103/physrevlett.114.258102] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Indexed: 05/27/2023]
Abstract
The microscopic stress field provides a unique connection between atomistic simulations and mechanics at the nanoscale. However, its definition remains ambiguous. Rather than a mere theoretical preoccupation, we show that this fact acutely manifests itself in local stress calculations of defective graphene, lipid bilayers, and fibrous proteins. We find that popular definitions of the microscopic stress violate the continuum statements of mechanical equilibrium, and we propose an unambiguous and physically sound definition.
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Affiliation(s)
| | - Juan M Vanegas
- LaCàN, Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
| | - Marino Arroyo
- LaCàN, Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
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Costescu BI, Gräter F. Graphene mechanics: II. Atomic stress distribution during indentation until rupture. Phys Chem Chem Phys 2015; 16:12582-90. [PMID: 24834440 DOI: 10.1039/c3cp55341h] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Previous Atomic Force Microscopy (AFM) experiments found single layers of defect-free graphene to rupture at unexpectedly high loads in the micronewton range. Using molecular dynamics simulations, we modeled an AFM spherical tip pressing on a circular graphene sheet and studied the stress distribution during the indentation process until rupture. We found the graphene rupture force to have no dependency on the sheet size and a very weak dependency on the indenter velocity, allowing a direct comparison to experiment. The deformation showed a non-linear elastic behavior, with a two-dimensional elastic modulus in good agreement with previous experimental and computational studies. In line with theoretical predictions for linearly elastic sheets, rupture forces of non-linearly elastic graphene are proportional to the tip radius. However, as a deviation from the theory, the atomic stress concentrates under the indenter tip more strongly than predicted and causes a high probability of bond breaking only in this area. In turn, stress levels decrease rapidly towards the edge of the sheet, most of which thus only serves the role of mechanical support for the region under the indenter. As a consequence, the high ratio between graphene sheets and sphere radii, hitherto supposed to be necessary for reliable deformation and rupture studies, could be reduced to a factor of only 5-10 without affecting the outcome. Our study suggests time-resolved analysis of forces at the atomic level as a valuable tool to predict and interpret the nano-scale response of stressed materials beyond graphene.
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Affiliation(s)
- Bogdan I Costescu
- Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany.
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