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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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2
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Flores-Ruiz H, Micoulaut M. From elemental tellurium to Ge 2Sb 2Te 5 melts: High temperature dynamic and relaxation properties in relationship with the possible fragile to strong transition. J Chem Phys 2018; 148:034502. [PMID: 29352786 DOI: 10.1063/1.5013668] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the dynamic properties of Ge-Sb-Te phase change melts using first principles molecular dynamics with a special emphasis on the effect of tellurium composition on melt dynamics. From structural models and trajectories established previously [H. Flores-Ruiz et al., Phys. Rev. B 92, 134205 (2015)], we calculate the diffusion coefficients for the different species, the activation energies for diffusion, the Van Hove correlation, and the intermediate scattering functions able to substantiate the dynamics and relaxation behavior of the liquids as a function of temperature and composition that is also compared to experiment whenever possible. We find that the diffusion is mostly Arrhenius-like and that the addition of Ge/Sb atoms leads to a global decrease of the jump probability and to an increase in activated dynamics for diffusion. Relaxation behavior is analyzed and used in order to evaluate the possibility of a fragile to strong transition that is evidenced from the calculated high fragility (M = 129) of Ge2Sb2Te5 at high temperatures.
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Affiliation(s)
- H Flores-Ruiz
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités - UPMC, Boite 121, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - M Micoulaut
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités - UPMC, Boite 121, 4, Place Jussieu, 75252 Paris Cedex 05, France
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Yildirim C, Raty JY, Micoulaut M. Anomalous diffusion and non-monotonic relaxation processes in Ge-Se liquids. J Chem Phys 2016; 144:224503. [PMID: 27306014 DOI: 10.1063/1.4953077] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the dynamical properties of liquid GexSe100-x as a function of Ge content by first-principles molecular dynamic simulations for a certain number of temperatures in the liquid state. The focus is set on ten compositions (where x ≤ 33%) encompassing the reported flexible to rigid and rigid to stressed-rigid transitions. We examine diffusion coefficients, diffusion activation energies, glassy relaxation behavior, and viscosity of these liquids from Van Hove correlation and intermediate scattering functions. At fixed temperature, all properties/functions exhibit an anomalous behavior with Ge content in the region 18%-22%, and provide a direct and quantitative link to the network rigidity.
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Affiliation(s)
- Can Yildirim
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4, Place Jussieu, 75252 Paris Cedex 05, France
| | - Jean-Yves Raty
- Physique des Solides, Interfaces et Nanostructures et SESAME, B5 Université de Liège, B4000 Sart-Tilman, Belgium
| | - Matthieu Micoulaut
- Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4, Place Jussieu, 75252 Paris Cedex 05, France
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Micoulaut M. Relaxation and physical aging in network glasses: a review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:066504. [PMID: 27213928 DOI: 10.1088/0034-4885/79/6/066504] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Recent progress in the description of glassy relaxation and aging are reviewed for the wide class of network-forming materials such as GeO2, Ge x Se1-x , silicates (SiO2-Na2O) or borates (B2O3-Li2O), all of which have an important usefulness in domestic, geological or optoelectronic applications. A brief introduction of the glass transition phenomenology is given, together with the salient features that are revealed both from theory and experiments. Standard experimental methods used for the characterization of the slowing down of the dynamics are reviewed. We then discuss the important role played by aspects of network topology and rigidity for the understanding of the relaxation of the glass transition, while also permitting analytical predictions of glass properties from simple and insightful models based on the network structure. We also emphasize the great utility of computer simulations which probe the dynamics at the molecular level, and permit the calculation of various structure-related functions in connection with glassy relaxation and the physics of aging which reveal the non-equilibrium nature of glasses. We discuss the notion of spatial variations of structure which leads to the concept of 'dynamic heterogeneities', and recent results in relation to this important topic for network glasses are also reviewed.
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Affiliation(s)
- Matthieu Micoulaut
- Paris Sorbonne Universités, LPTMC-UPMC, 4 place Jussieu, 75252 Paris cedex 05, France
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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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6
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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: 17] [Impact Index Per Article: 1.9] [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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Bauchy M, Kachmar A, Micoulaut M. Structural, dynamic, electronic, and vibrational properties of flexible, intermediate, and stressed rigid As-Se glasses and liquids from first principles molecular dynamics. J Chem Phys 2014; 141:194506. [DOI: 10.1063/1.4901515] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- M. Bauchy
- Department of Civil and Environmental Engineering, University of California, Los Angeles, California 90095-1593, USA
| | - A. Kachmar
- Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05, France
- Qatar Environment and Energy Research Institute, Qatar Foundation, P.O. Box 5825, Doha, Qatar
| | - M. Micoulaut
- Laboratoire de Physique Théorique de la Matière Condensée, Université Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris Cedex 05, France
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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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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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10
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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: 13] [Impact Index Per Article: 1.1] [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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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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12
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Bauchy M. Structural, vibrational, and thermal properties of densified silicates: Insights from molecular dynamics. J Chem Phys 2012; 137:044510. [DOI: 10.1063/1.4738501] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Marrocchelli D, Salanne M, Madden P, Simon C, Turq P. The construction of a reliable potential for GeO2 from first principles. Mol Phys 2010. [DOI: 10.1080/00268970902845347] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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15
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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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Vaccari M, Aquilanti G, Pascarelli S, Mathon O. A new EXAFS investigation of local structural changes in amorphous and crystalline GeO(2) at high pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:145403. [PMID: 21825334 DOI: 10.1088/0953-8984/21/14/145403] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Structural transformations at high pressure in amorphous and quartz-like crystalline GeO(2) have been investigated by using a Paris-Edinburgh press coupled to EXAFS spectroscopy. From both the germanium absorption edge position and the Ge-O distance evolution, new detailed information has been obtained about the pressure behavior of the short range order. Crystalline GeO(2) undergoes a transformation from four- to six-fold coordination at about 8.5 GPa, but at least the whole 6-12 GPa pressure range should be considered as the transition region. On the other hand, amorphous GeO(2) is characterized by a much more gradual structural change and the full octahedral state is not reached at 13 GPa as commonly believed. Furthermore, no support to the recently claimed fully pentahedral intermediate state can be given. EXAFS signals of glassy GeO(2) beyond the first Ge-O shell qualitatively confirm the continuous breakdown of the intermediate range order up to 10 GPa.
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Affiliation(s)
- M Vaccari
- European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex, France
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Li T, Huang S, Zhu J. The structure and void analysis of pressure-induced amorphous GeO2: Molecular dynamics simulation. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.02.059] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Hoang VV. The glass transition and diffusion in simulated liquid TiO 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:416109. [PMID: 28192341 DOI: 10.1088/0953-8984/19/41/416109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The glass transition and diffusion in liquid TiO2 have been studied in a model containing 3000 atoms via molecular dynamics (MD) simulation. The density dependence of the glass transition temperature, Tg, of liquid TiO2 has been found and is discussed. Diffusion of atomic species in 3.80 g cm-3 TiO2 models has been investigated over a wide temperature range from 2100 to 7000 K. We found that the temperature dependence of the diffusion constant of atomic species follows an Arrhenius law at relatively low temperatures above the melting point, and at higher temperatures it deviates from an Arrhenius law. Differences between the structures of amorphous TiO2 models at three different densities in the range from 3.80 to 4.20 g cm-3 have been found and are discussed. In addition, a transition from a low-density liquid (ldl) form to a high-density liquid (hdl) form was found and is discussed.
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Affiliation(s)
- Vo Van Hoang
- Department of Physics, Institute of Technology, National University of HochiMinh City, 268 Ly Thuong Kiet Street, District 10, HochiMinh City, Vietnam
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Giacomazzi L, Pasquarello A. Vibrational spectra of vitreous SiO 2 and vitreous GeO 2 from first principles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:415112. [PMID: 28192324 DOI: 10.1088/0953-8984/19/41/415112] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Using a density-functional approach, we calculate the principal vibrational spectra of vitreous SiO2 and vitreous GeO2 and discuss their analogies and differences. For both glasses, we generate model structures consisting of a random network of corner-sharing tetrahedra and differing only by their packing density. The comparison between calculated and measured neutron structure factors supports the validity of our model structures. Our investigation then extends to the vibrational properties, including the inelastic-neutron, infrared, and Raman spectra. For these spectra, good agreement with experiment is also found. Our results support the picture that silica and germania are constituted by a continuous random network of corner-sharing tetrahedra. In particular, the good agreement with experiment for the Raman spectra supports the average intertetrahedral angles of 148° and 135° found in our models of vitreous SiO2 and vitreous GeO2, respectively. The concentration of small ring structures in these glasses is also discussed.
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Salmon PS, Barnes AC, Martin RA, Cuello GJ. Structure of glassy GeO 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:415110. [PMID: 28192322 DOI: 10.1088/0953-8984/19/41/415110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The full set of partial structure factors for glassy germania, or GeO2, were accurately measured by using the method of isotopic substitution in neutron diffraction in order to elucidate the nature of the pair correlations for this archetypal strong glass former. The results show that the basic tetrahedral Ge(O1/2)4 building blocks share corners with a mean inter-tetrahedral Ge-Ô-Ge bond angle of 132(2)°. The topological and chemical ordering in the resultant network displays two characteristic length scales at distances greater than the nearest neighbour. One of these describes the intermediate range order, and manifests itself by the appearance of a first sharp diffraction peak in the measured diffraction patterns at a scattering vector kFSDP≈1.53 Å-1, while the other describes so-called extended range order, and is associated with the principal peak at kPP = 2.66(1) Å-1. We find that there is an interplay between the relative importance of the ordering on these length scales for tetrahedral network forming glasses that is dominated by the extended range ordering with increasing glass fragility. The measured partial structure factors for glassy GeO2 are used to reproduce the total structure factor measured by using high energy x-ray diffraction and the experimental results are also compared to those obtained by using classical and first principles molecular dynamics simulations.
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