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Anzellini S, Alfé D, Pozzo M, Errandonea D. Melting line of calcium characterized by in situ LH-DAC XRD and first-principles calculations. Sci Rep 2021; 11:15025. [PMID: 34294781 PMCID: PMC8298416 DOI: 10.1038/s41598-021-94349-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 07/09/2021] [Indexed: 11/16/2022] Open
Abstract
In this work, the melting line of calcium has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using first-principles calculations. In the investigated pressure and temperature range (pressure between 10 and 40 GPa and temperature between 300 and 3000 K) it was possible to observe the face-centred phase of calcium and to confirm (and characterize for the first time at these conditions) the presence of the body-centred cubic and the simple cubic phase of calcium. The melting points obtained with the two techniques are in excellent agreement. Furthermore, the present results agree with the only existing melting line of calcium obtained in laser-heated diamond anvil cells, using the speckle method as melting detection technique. They also confirm a flat slope of the melting line in the pressure range between 10 and 30 GPa. The flat melting curve is associated with the presence of the solid high-temperature body-centered cubic phase of calcium and to a small volume change between this phase and the liquid at melting. Reasons for the stabilization of the body-centered face at high-temperature conditions will be discussed.
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Affiliation(s)
- Simone Anzellini
- Diamond Light Source Ltd., Harwell Science & Innovation Campus, Diamond House, Didcot, OX11 0DE, UK.
| | - Dario Alfé
- Dipartimento di Fisica Ettore Pancini, Università di Napoli Federico II, Monte S. Angelo, 80126, Napoli, Italy.,Department of Earth Sciences and London Centre for Nanotechnology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Monica Pozzo
- Department of Earth Sciences and London Centre for Nanotechnology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Daniel Errandonea
- Departamento de Física Aplicada - Instituto de Ciencia de Materiales, Matter at High Pressure (MALTA) Consolider Team, Universidad de Valencia, Edificio de Investigación, C/Dr. Moliner 50, Burjassot, Valencia, 46100, Spain
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Novoselov DY, Korotin DM, Shorikov AO, Oganov AR, Anisimov VI. Weak Coulomb correlations stabilize the electride high-pressure phase of elemental calcium. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:445501. [PMID: 32503018 DOI: 10.1088/1361-648x/ab99ed] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
Theoretical studies using the state-of-the-art density functional theory and dynamicalmean-field theory (DFT + DMFT) method show that weak electronic correlation effects are crucial for reproducing the experimentally observed pressure-induced phase transitions of calcium from β-tin toCmmmand then to the simple cubic structure. The formation of an electride state in calcium leads to the emergence of partially filled and localized electronic states under compression. The electride state was described using a basis containing molecular orbitals centered on the interstitial site and Ca-d states. We investigate the influence of Coulomb correlations on the structural properties of elemental Ca, noting that approaches based on the Hartree-Fock method (DFT +Uor hybrid functional schemes) are poorly suited for describing correlated metals. We find that only the DFT + DMFT method reproduces the correct sequence of high-pressure phase transitions of Ca at low temperatures.
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Affiliation(s)
- Dmitry Y Novoselov
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences-620108, Yekaterinburg, Russia
- Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Mira St. 19, 620002 Yekaterinburg, Russia
- Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow, 143026, Russia
| | - Dmitry M Korotin
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences-620108, Yekaterinburg, Russia
- Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow, 143026, Russia
| | - Alexey O Shorikov
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences-620108, Yekaterinburg, Russia
- Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Mira St. 19, 620002 Yekaterinburg, Russia
- Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow, 143026, Russia
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow, 143026, Russia
- Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow Region, 141701, Russia
| | - Vladimir I Anisimov
- M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences-620108, Yekaterinburg, Russia
- Department of Theoretical Physics and Applied Mathematics, Ural Federal University, Mira St. 19, 620002 Yekaterinburg, Russia
- Skolkovo Institute of Science and Technology, 3 Nobel St., Moscow, 143026, Russia
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