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Renthlei Z, Prasad M, Sivakumar J, Zuala L, Pachuau L, Devi YR, Singh NS, Abdurakhmanov G, Laref A, Rai DP. A Thorough Investigation of Electronic, Optical, Mechanical, and Thermodynamic Properties of Stable Glasslike Sodium Germanate under Compressive Hydrostatic Pressure: Ab Initio Study. ACS OMEGA 2023; 8:16869-16882. [PMID: 37214663 PMCID: PMC10193426 DOI: 10.1021/acsomega.3c00499] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 04/10/2023] [Indexed: 05/24/2023]
Abstract
In this paper, we have tried to elucidate the variation of structural, electronic, and thermodynamic properties of glasslike Na2GeO3 under compressive isotropic pressure within a framework of density functional theory (DFT). The result shows stable structural (orthorhombic → tetragonal) and electronic (indirect → direct) phase transitions at P ∼ 20 GPa. The electronic band gap transition plays a key role in the enhancement of optical properties. The results of the thermodynamic properties have shown that Na2GeO3 follows Debye's low-temperature specific heat law and the classical thermodynamic of the Dulong-Petit law at high temperature. The pressure sensitivity of the electronic properties led us to compute the piezoelectric tensor (both in relaxed and clamped ions). We have observed significant electric responses in the form of a piezoelectric coefficient under applied pressure. This property suggested that Na2GeO3 could be a potential material for energy harvest in future energy-efficient devices. As expected, Na2GeO3 becomes harder and harder under compressive pressure up to the phase transition pressure (∼20 GPa) which can be read from Pugh's ratio (kH) > 1.75, however, at pressures above 20 GPa kH < 1.75, which may be due to the formation of fractures at high pressure.
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Affiliation(s)
- Zosiamliana Renthlei
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
- Department
of Physics, Mizoram University, Aizawl 796009, India
| | - Mattipally Prasad
- Department
of Physics, University College of Science, Osmania University, Hyderabad, Telangana 500007, India
| | - Juluru Sivakumar
- Department
of Physics, University College of Science, Osmania University, Hyderabad, Telangana 500007, India
| | - Lalhriat Zuala
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
| | - Lalrinthara Pachuau
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
| | - Yengkhom Rangeela Devi
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
| | - Ningthoujam Surajkumar Singh
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
| | | | - Amel Laref
- Department
of Physics and Astronomy, College of Science,
King Saud University, Riyadh 11451, Saudi Arabia
| | - Dibya Prakash Rai
- Physical
Sciences Research Center (PSRC), Department of Physics, Pachhunga University College, Mizoram
University, Aizawl 796001, India
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Hong X, Newville M, Ding Y. Local structural investigation of non-crystalline materials at high pressure: the case of GeO 2glass. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2023; 35:164001. [PMID: 36764002 DOI: 10.1088/1361-648x/acbb4c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Local structures play a crucial role in the structural polyamorphism and novel electronic properties of amorphous materials, but their accurate measurement at high pressure remains a formidable challenge. In this article, we use the local structure of network-forming GeO2glass as an example, to present our recent approaches and advances in high-energy x-ray diffraction, high-pressure x-ray absorption fine structure, andab initiofirst-principles density functional theory calculations and simulations. Although GeO2glass is one of the best studied materials in the field of high pressure research due to its importance in glass theory and geophysical significance, there are still some long-standing puzzles, such as the existence of appreciable distinct fivefold[5]Ge coordination at low pressure and the sixfold-plus[6+]Ge coordination at ultrahigh pressure. Our work sheds light on the origin of pressure-induced polyamorphism of GeO2glass, and the[5]Ge polyhedral units may be the dominant species in the densification mechanism of network-forming glasses from tetrahedral to octahedral amorphous structures.
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Affiliation(s)
- Xinguo Hong
- Center for High Pressure Science and Technology Advanced Research, Beijing 100193, People's Republic of China
| | - Matt Newville
- Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, United States of America
| | - Yang Ding
- Center for High Pressure Science and Technology Advanced Research, Beijing 100193, People's Republic of China
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Ha L, Kien PH. Domain Structural Transition and Structural Heterogeneity in GeO 2 Glass Under Densification. ACS OMEGA 2020; 5:29092-29101. [PMID: 33225140 PMCID: PMC7675545 DOI: 10.1021/acsomega.0c03722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/14/2020] [Indexed: 06/11/2023]
Abstract
The domain structural transition and structural heterogeneity (SH) in GeO2 glass at 300 K and pressures up to 100 GPa are studied by means of molecular dynamics (MD) simulation. The results demonstrate that the structure of GeO2 glass comprises domain D4, domain D5, or domain D6, which depends strongly on pressure, where domain Dx (x = 4, 5, or 6) is a cluster of connected GeO x units, in which all Ge atoms possess the same coordination number of x. In the range of 9-18 GPa, GeO2 glass undergoes a structural transformation from domain D4 to domain D6 via domain D5. Under densification, structural evolution occurs along with the O xx → O xy atom variation, which comprises the processes of both merging and splitting of domain Dx and the exchange of domain-boundary (DB) atoms. The densification leads to a decrease of the Voronoi polygon (VP) volume of atoms. We found that the coexistence of separate domain structures is the origin of spatial SH in GeO2 glass. Pressure-dependent structural heterogeneity in GeO2 glass is also discussed in detail.
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Affiliation(s)
- LeTien Ha
- Ceramics
and Biomaterials Research Group, Advanced Institute of Materials Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam
- Faculty
of Applied Sciences, Ton Duc Thang
University, Ho Chi Minh City, Vietnam
| | - Pham Huu Kien
- Institute
of Research and Development, Duy Tan University, Da Nang 550000, Vietnam
- Thai
Nguyen University of Education, 20 Luong Ngoc Quyen, Thai Nguyen 250000, Vietnam
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4
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Huy HA, Nguyen LT, Nguyen DLT, Truong TQ, Ong LK, Van Hoang V, Nguyen GH. Novel pressure-induced topological phase transitions of supercooled liquid and amorphous silicene. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:095403. [PMID: 30523966 DOI: 10.1088/1361-648x/aaf402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This molecular dynamics (MD) simulation carries a detailed analysis of a pressure-induced structural transition supercooled liquid and amorphous silicene (a-silicene). Low-density models of supercooled liquid and a-silicene containing 10 000 atoms are obtained by rapid cooling processes from the melts. Then, an a-silicene model at T = 1000 K, a supercooled liquid model at T = 1500 K and a liquid silicon model at T = 2000 K have been isothermally compressed step by step up to a high density in order to observe the pressure-induced structural changes. Specifically 'Cairo tiling' pentagonal and square lattices of silicene are discovered in our calculations. Structural properties of those penta-silicene and tetra-silicene models have been carefully analyzed through the radial distribution functions, interatomic distances, bond-angle distributions under high-pressure condition. The dependence of pressure on formation behaviors is calculated via pressure-volume and energy-density relationships. The first order transition from low-density supercooled liquid/amorphous silicene to high-density penta-silicene and continuous transition from low-density liquid to high-density tetra-silicene are discussed. Atomic mechanism and sp3/sp2 hybridization evolution are inspected whereas the role of low-membered ring defects/boundary promises remarkable application and advanced research in future.
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Affiliation(s)
- Huynh Anh Huy
- Department of Physics, College of Education, Can Tho University, Can Tho City, Vietnam
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5
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De Backer A, Domain C, Becquart CS, Luneville L, Simeone D, Sand AE, Nordlund K. A model of defect cluster creation in fragmented cascades in metals based on morphological analysis. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:405701. [PMID: 30124201 DOI: 10.1088/1361-648x/aadb4e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The impacts of ions and neutrons in metals cause cascades of atomic collisions that expand and shrink, leaving microstructure defect debris, i.e. interstitial or vacancy clusters or loops of different sizes. In De Backer et al (2016 Europhys. Lett. 115 26001), we described a method to detect the first morphological transition, i.e. the cascade fragmentation in subcascades, and a model of primary damage combining the binary collision approximation and molecular dynamics (MD). In this paper including W, Fe, Be, Zr and 20 other metals, we demonstrate that the fragmentation energy increases with the atomic number and decreases with the atomic density following a unique power law. Above the fragmentation energy, the cascade morphology can be characterized by the cross pair correlation functions of the multitype point pattern formed by the subcascades. We derive the numbers of pairs of subcascades and observed that they follow broken power laws. The energy where the power law breaks indicates the second morphological transition when cascades are formed by branches decorated by chaplets of small subcascades. The subcascade interaction is introduced in our model of primary damage by adding pairwise terms. Using statistics obtained on hundreds of MD cascades in Fe, we demonstrate that the interaction of subcascades increases the proportion of large clusters in the damage created by high energy cascades. Finally, we predict the primary damage of 500 keV Fe ion in Fe and obtain cluster size distributions when large statistics of MD cascades are not feasible.
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Affiliation(s)
- A De Backer
- CCFE-Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB, United Kingdom
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Dong J, Yao H, Guo Z, Jia Q, Wang Y, An P, Gong Y, Liang Y, Chen D. Revisiting local structural changes in GeO 2 glass at high pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:465401. [PMID: 29053477 DOI: 10.1088/1361-648x/aa8d50] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Despite the great importance in fundamental and industrial fields, understanding structural changes for pressure-induced polyamorphism in network-forming glasses remains a formidable challenge. Here, we revisited the local structural transformations in GeO2 glass up to 54 GPa using x-ray absorption fine structure (XAFS) spectroscopy via a combination diamond anvil cell and polycapillary half-lens. Three polyamorphic transitions can be clearly identified by XAFS structure refinement. First, a progressive increase of the nearest Ge-O distance and bond disorder to a maximum at ~5-16 GPa, in the same pressure region of previously observed tetrahedral-octahedral transformation. Second, a marked decrease of the nearest Ge-O distance at ~16-22.6 GPa but a slight increase at ~22.6-32.7 GPa, with a concomitant decrease of bond disorder. This stage can be related to a second-order-like transition from less dense to dense octahedral glass. Third, another decrease in the nearest Ge-O distance at ~32.7-41.4 GPa but a slight increase up to 54 GPa, synchronized with a gradual increase of bond disorder. This stage provides strong evidence for ultrahigh-pressure polyamorphism with coordination number >6. Furthermore, cooperative modification is observed in more distant shells. Those results provide a unified local structural picture for elucidating the polyamorphic transitions and densification process in GeO2 glass.
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Affiliation(s)
- Juncai Dong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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7
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Liu X, Zheng D, Ren X, He L, Chen M. First-principles molecular dynamics study of deuterium diffusion in liquid tin. J Chem Phys 2017; 147:064505. [PMID: 28810782 DOI: 10.1063/1.4997635] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding the retention of hydrogen isotopes in liquid metals, such as lithium and tin, is of great importance in designing a liquid plasma-facing component in fusion reactors. However, experimental diffusivity data of hydrogen isotopes in liquid metals are still limited or controversial. We employ first-principles molecular dynamics simulations to predict diffusion coefficients of deuterium in liquid tin at temperatures ranging from 573 to 1673 K. Our simulations indicate faster diffusion of deuterium in liquid tin than the self-diffusivity of tin. In addition, we find that the structural and dynamic properties of tin are insensitive to the inserted deuterium at temperatures and concentrations considered. We also observe that tin and deuterium do not form stable solid compounds. These predicted results from simulations enable us to have a better understanding of the retention of hydrogen isotopes in liquid tin.
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Affiliation(s)
- Xiaohui Liu
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Daye Zheng
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Xinguo Ren
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Lixin He
- CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China
| | - Mohan Chen
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
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8
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Burbano M, Carlier D, Boucher F, Morgan BJ, Salanne M. Sparse Cyclic Excitations Explain the Low Ionic Conductivity of Stoichiometric Li_{7}La_{3}Zr_{2}O_{12}. PHYSICAL REVIEW LETTERS 2016; 116:135901. [PMID: 27081991 DOI: 10.1103/physrevlett.116.135901] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Indexed: 05/03/2023]
Abstract
We have performed long time scale molecular dynamics simulations of the cubic and tetragonal phases of the solid lithium-ion electrolyte Li_{7}La_{3}Zr_{2}O_{12} (LLZO), using a first-principles parametrized interatomic potential. Collective lithium transport was analyzed by identifying dynamical excitations: persistent ion displacements over distances comparable to the separation between lithium sites, and stringlike clusters of ions that undergo cooperative motion. We find that dynamical excitations in c-LLZO (cubic) are frequent, with participating lithium numbers following an exponential distribution, mirroring the dynamics of fragile glasses. In contrast, excitations in t-LLZO (tetragonal) are both temporally and spatially sparse, consisting preferentially of highly concerted lithium motion around closed loops. This qualitative difference is explained as a consequence of lithium ordering in t-LLZO and provides a mechanistic basis for the much lower ionic conductivity of t-LLZO compared to c-LLZO.
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Affiliation(s)
- Mario Burbano
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, PHENIX, F-75005 Paris, France
- CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France
| | - Dany Carlier
- CNRS, Université de Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, 33608 Pessac Cedex, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France
| | - Florent Boucher
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes cedex 3, France
| | - Benjamin J Morgan
- Department of Chemistry, University of Bath, Claverton Down BA2 7AY, United Kingdom
| | - Mathieu Salanne
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8234, PHENIX, F-75005 Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France
- Maison de la Simulation, USR 3441, CEA-CNRS-INRIA-Université Paris-Sud-Université de Versailles, F-91191 Gif-sur-Yvette, France
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9
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Pacaud F, Micoulaut M. Thermodynamic precursors, liquid-liquid transitions, dynamic and topological anomalies in densified liquid germania. J Chem Phys 2015; 143:064502. [DOI: 10.1063/1.4927707] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Salmon PS, Zeidler A. Networks under pressure: the development of in situ high-pressure neutron diffraction for glassy and liquid materials. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:133201. [PMID: 25743915 DOI: 10.1088/0953-8984/27/13/133201] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The pressure-driven collapse in the structure of network-forming materials will be considered in the gigapascal (GPa) regime, where the development of in situ high-pressure neutron diffraction has enabled this technique to obtain new structural information. The improvements to the neutron diffraction methodology are discussed, and the complementary nature of the results is illustrated by considering the pressure-driven structural transformations for several key network-forming materials that have also been investigated by using other experimental techniques such as x-ray diffraction, inelastic x-ray scattering, x-ray absorption spectroscopy and Raman spectroscopy. A starting point is provided by the pressure-driven network collapse of the prototypical network-forming oxide glasses B2O3, SiO2 and GeO2. Here, the combined results help to show that the coordination number of network-forming structural motifs in a wide range of glassy and liquid oxide materials can be rationalised in terms of the oxygen-packing fraction over an extensive pressure and temperature range. The pressure-driven network collapse of the prototypical chalcogenide glass GeSe2 is also considered where, as for the case of glassy GeO2, site-specific structural information is now available from the method of in situ high-pressure neutron diffraction with isotope substitution. The application of in situ high-pressure neutron diffraction to other structurally disordered network-forming materials is also summarised. In all of this work a key theme concerns the rich diversity in the mechanisms of network collapse, which drive the changes in physico-chemical properties of these materials. A more complete picture of the mechanisms is provided by molecular dynamics simulations using theoretical schemes that give a good account of the experimental results.
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11
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Hong X, Newville M, Duffy TS, Sutton SR, Rivers ML. X-ray absorption spectroscopy of GeO2 glass to 64 GPa. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:035104. [PMID: 24285424 DOI: 10.1088/0953-8984/26/3/035104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The structural behavior of GeO2 glass has been investigated up to 64 GPa using results from x-ray absorption spectroscopy in a diamond anvil cell combined with previously reported density measurements. The difference between the nearest Ge-O distances of glassy and rutile-type GeO2 disappears at the Ge-O distance maximum at 20 GPa, indicating completion of the tetrahedral-octahedral transition in GeO2 glass. The mean-square displacement σ(2) of the Ge-O distance in the first Ge-O shell increases progressively to a maximum at 10 GPa, followed by a substantial reduction at higher pressures. The octahedral glass is, as expected, less dense and has a higher compressibility than the corresponding crystalline phase, but the differences in Ge-O distance and density between the glass and the crystals are gradually eliminated over the 20-40 GPa pressure range. Above 40 GPa, GeO2 forms a dense octahedral glass with a compressibility similar to that of the corresponding crystalline phase (α-PbO2 type). The EXAFS and XANES spectra show evidence for subtle changes in the dense glass continuing to occur at these high pressures. The Ge-O bond distance shows little change between 45-64 GPa, and this may reflect a balance between bond shortening and a gradual coordination number increase with compression. The density of the glass is similar to that of the α-PbO2-type phase, but the Ge-O distance is longer and is close to that in the higher-coordination pyrite-type phase which is stable above ∼60 GPa. The density data provide evidence for a possible discontinuity and change in compressibility at 40-45 GPa, but there are no major changes in the corresponding EXAFS spectra. A pyrite-type local structural model for the glass can provide a reasonable fitting to the XAFS spectra at 64 GPa.
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Affiliation(s)
- Xinguo Hong
- Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794, USA
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12
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Salmon PS, Zeidler A. Identifying and characterising the different structural length scales in liquids and glasses: an experimental approach. Phys Chem Chem Phys 2013; 15:15286-308. [DOI: 10.1039/c3cp51741a] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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13
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Wezka K, Salmon PS, Zeidler A, Whittaker DAJ, Drewitt JWE, Klotz S, Fischer HE, Marrocchelli D. Mechanisms of network collapse in GeO2 glass: high-pressure neutron diffraction with isotope substitution as arbitrator of competing models. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:502101. [PMID: 23164808 DOI: 10.1088/0953-8984/24/50/502101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The structure of the network forming glass GeO(2) is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only with molecular dynamics simulations made using interaction potentials that include dipole-polarization effects. When the reduced density ρ/ρ(0) > or approximately equal to 1.16, where ρ(0) is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO(5) units versus octahedral GeO(6) units as they replace tetrahedral GeO(4) units. This replacement necessitates the formation of threefold coordinated oxygen atoms and leads to an increase with density in the number of small rings, where a preference is shown for sixfold rings when ρ/ρ(0) = 1 and fourfold rings when ρ/ρ(0) = 1.64.
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Affiliation(s)
- Kamil Wezka
- Department of Physics, University of Bath, Bath, UK
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14
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Salmon PS, Drewitt JWE, Whittaker DAJ, Zeidler A, Wezka K, Bull CL, Tucker MG, Wilding MC, Guthrie M, Marrocchelli D. Density-driven structural transformations in network forming glasses: a high-pressure neutron diffraction study of GeO2 glass up to 17.5 GPa. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:415102. [PMID: 22951604 DOI: 10.1088/0953-8984/24/41/415102] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The structure of GeO(2) glass was investigated at pressures up to 17.5(5) GPa using in situ time-of-flight neutron diffraction with a Paris-Edinburgh press employing sintered diamond anvils. A new methodology and data correction procedure were developed, enabling a reliable measurement of structure factors that are largely free from diamond Bragg peaks. Calibration curves, which are important for neutron diffraction work on disordered materials, were constructed for pressure as a function of applied load for both single and double toroid anvil geometries. The diffraction data are compared to new molecular-dynamics simulations made using transferrable interaction potentials that include dipole-polarization effects. The results, when taken together with those from other experimental methods, are consistent with four densification mechanisms. The first, at pressures up to approximately equal 5 GPa, is associated with a reorganization of GeO(4) units. The second, extending over the range from approximately equal 5 to 10 GPa, corresponds to a regime where GeO(4) units are replaced predominantly by GeO(5) units. In the third, as the pressure increases beyond ~10 GPa, appreciable concentrations of GeO(6) units begin to form and there is a decrease in the rate of change of the intermediate-range order as measured by the pressure dependence of the position of the first sharp diffraction peak. In the fourth, at about 30 GPa, the transformation to a predominantly octahedral glass is achieved and further densification proceeds via compression of the Ge-O bonds. The observed changes in the measured diffraction patterns for GeO(2) occur at similar dimensionless number densities to those found for SiO(2), indicating similar densification mechanisms for both glasses. This implies a regime from about 15 to 24 GPa where SiO(4) units are replaced predominantly by SiO(5) units, and a regime beyond ~24 GPa where appreciable concentrations of SiO(6) units begin to form.
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15
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Tazi S, Molina JJ, Rotenberg B, Turq P, Vuilleumier R, Salanne M. A transferable ab initio based force field for aqueous ions. J Chem Phys 2012; 136:114507. [PMID: 22443777 DOI: 10.1063/1.3692965] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
We present a new polarizable force field for aqueous ions (Li(+), Na(+), K(+), Rb(+), Cs(+), Mg(2 +), Ca(2 +), Sr(2 +), and Cl(-)) derived from condensed phase ab initio calculations. We use maximally localized Wannier functions together with a generalized force and dipole-matching procedure to determine the whole set of parameters. Experimental data are then used only for validation purposes and a good agreement is obtained for structural, dynamic, and thermodynamic properties. The same procedure applied to crystalline phases allows to parametrize the interaction between cations and the chloride anion. Finally, we illustrate the good transferability of the force field to other thermodynamic conditions by investigating concentrated solutions.
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Affiliation(s)
- Sami Tazi
- UPMC Universitá Paris 06, CNRS, ESPCI, UMR 7195 PECSA, F-75005 Paris, France
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Hong X, Chen Z, Duffy TS. Absolute x-ray energy calibration over a wide energy range using a diffraction-based iterative method. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:063901. [PMID: 22755637 DOI: 10.1063/1.4722166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In this paper, we report a method of precise and fast absolute x-ray energy calibration over a wide energy range using an iterative x-ray diffraction based method. Although accurate x-ray energy calibration is indispensable for x-ray energy-sensitive scattering and diffraction experiments, there is still a lack of effective methods to precisely calibrate energy over a wide range, especially when normal transmission monitoring is not an option and complicated micro-focusing optics are fixed in place. It is found that by using an iterative algorithm the x-ray energy is only tied to the relative offset of sample-to-detector distance, which can be readily varied with high precision of the order of 10(-5) -10(-6) spatial resolution using gauge blocks. Even starting with arbitrary initial values of 0.1 Å, 0.3 Å, and 0.4 Å, the iteration process converges to a value within 3.5 eV for 31.122 keV x-rays after three iterations. Different common diffraction standards CeO(2), Au, and Si show an energy deviation of 14 eV. As an application, the proposed method has been applied to determine the energy-sensitive first sharp diffraction peak of network forming GeO(2) glass at high pressure, exhibiting a distinct behavior in the pressure range of 2-4 GPa. Another application presented is pair distribution function measurement using calibrated high-energy x-rays at 82.273 keV. Unlike the traditional x-ray absorption-based calibration method, the proposed approach does not rely on any edges of specific elements, and is applicable to the hard x-ray region where no appropriate absorption edge is available.
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Affiliation(s)
- Xinguo Hong
- Mineral Physics Institute, Stony Brook University, Stony Brook, New York 11794, USA.
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Burbano M, Marrocchelli D, Yildiz B, Tuller HL, Norberg ST, Hull S, Madden PA, Watson GW. A dipole polarizable potential for reduced and doped CeO(2) obtained from first principles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:255402. [PMID: 21654047 DOI: 10.1088/0953-8984/23/25/255402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this paper we present the parameterization of a new interionic potential for stoichiometric, reduced and doped CeO(2). We use a dipole polarizable potential (DIPPIM: the dipole polarizable ion model) and optimize its parameters by fitting them to a series of density functional theory calculations. The resulting potential was tested by calculating a series of fundamental properties for CeO(2) and by comparing them against experimental values. The values for all the calculated properties (thermal and chemical expansion coefficients, lattice parameters, oxygen migration energies, local crystalline structure and elastic constants) are within 10-15% of the experimental ones, an accuracy comparable to that of ab initio calculations. This result suggests the use of this new potential for reliably predicting atomic scale properties of CeO(2) in problems where ab initio calculations are not feasible due to their size limitations.
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Affiliation(s)
- Mario Burbano
- School of Chemistry and CRANN, Trinity College Dublin, Dublin 2, Ireland
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Jabes BS, Agarwal M, Chakravarty C. Tetrahedral order, pair correlation entropy, and waterlike liquid state anomalies: Comparison of GeO2 with BeF2, SiO2, and H2O. J Chem Phys 2010; 132:234507. [DOI: 10.1063/1.3439593] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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