A neutron diffraction investigation of the structure of vitreous germania

Desa, J.A.E.; Wright, Adrian C.; Sinclair, Roger N.

doi:10.1016/0022-3093(88)90437-1

Cited by 70 publications

(19 citation statements)

References 24 publications

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“…Most GeO 4 units are connected by corner-sharing bonds and about 1.1% of GeO 4 units are linked by two and three bridge-oxygen atoms. Our simulation reproduces well the experimental , and simulation data. , Figure shows the g Ge‑Ge ( r ), g Ge‑O ( r ), and g O‑O ( r ) PRDFs at dissimilar pressures. As seen, at 0 GPa, the PRDF g Ge‑Ge ( r ) possesses a main peak located in the range of 3.12–3.20 Å and a small peak located at around 3.42 Å.…”

Section: Resultssupporting

confidence: 74%

Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Kien

2020

ACS Omega

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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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Section: Resultssupporting

confidence: 74%

Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Kien

2020

ACS Omega

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“…Furthermore, the larger amount of three-membered rings observed in germania with respect to silica is reflected in the lower mean of the Ge−O−Ge angle. 13 For silica, a thin-film strategy has been employed for the identification of local site geometries, tetrahedral building blocks and larger building units, i.e., rings. Studies of monolayer silica films grown on Ru(0001) and Mo(112) substrates reveal a hexagonal crystalline network of cornersharing SiO 4 tetrahedra.…”

Section: ■ Introductionmentioning

confidence: 99%

“…However, the intertetrahedral angle Ge–O–Ge exhibits a narrower distribution than the Si–O–Si angle. Furthermore, the larger amount of three-membered rings observed in germania with respect to silica is reflected in the lower mean of the Ge–O–Ge angle …”

Section: Introductionmentioning

confidence: 99%

Determination of Silica and Germania Film Network Structures on Ru(0001) at the Atomic Scale

et al. 2018

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The detailed structure of silica and germania films supported on Ru(0001) metal substrates are compared to each other. Surface science techniques together with density functional theory calculations have been used to gain insights into the atomic arrangement of these prominent glass-forming materials. The monolayer films of these materials both show predominantly crystalline hexagonal lattices with characteristic domain boundary structures. For the germania monolayer films a large variety of ring elements within domain boundaries have been observed. Density functional calculations predict stronger interaction with the metal substrate for bilayer germania as compared to bilayer silica films. Scanning tunneling microscopy images with atomically resolved structural features have given access to silica and germania bilayer film structures. Both bilayer films form characteristic amorphous ring structures. However, the germania bilayer films appear to be more corrugated, pointing to a stronger interaction with the metal support thus giving rise to slightly different connectivity rules.

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“…The crystalline and vitreous forms of germania, GeO 2 have been extensively studied using a wide range of static and dynamic compression techniques [1][2][3] . The structure of amorphous germania at high pressure has been examined using x-ray absorption spectroscopy [4][5][6][7] , Raman 8 and Infrared spectroscopy 9 as well as x-ray [10][11][12][13] and neutron diffraction [14][15][16] . Static compression experiments on crystalline GeO 2 have concentrated on the high-pressure crystal structure [17][18][19] and phase transitions [20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

Equation of state of theα−PbO2andPa3¯-type phases of
Dutta
¹
,
White
²
,
Greenberg
³

et al. 2018
Phys. Rev. B

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The compression behavior of crystalline and amorphous germania holds considerable interest as an analog for silica and for understanding the structural response of AX 2 compounds generally. In this work, the α-PbO 2 -type and 3-type polymorphs of GeO 2 were investigated under high pressure using angle-dispersive synchrotron x-ray diffraction in the laser-heated diamond anvil cell. Theoretical calculations based on density functional theory were also performed. The experimental pressure-volume data were fitted to 3 rd order Birch-Murnaghan equations of state. The fit parameters for the α-PbO 2 -type are: V 0 = 53.8 (2) Å 3 , K 0T = 293 (7) GPa with fixed 4; where V, K T , and are the volume, isothermal bulk modulus, and pressure derivative of the bulk modulus and the subscript 0 refers to ambient conditions. The corresponding parameters for the 3-type phase is: V 0 = 50.3 (3) Å 3 , K 0T = 342 (12) GPa with fixed 4. The theoretical calculations are in good agreement with the experimental results with slight underestimation and overestimation of V 0 and K 0T respectively. A theoretical Hugoniot was calculated from our data and compared to shock equation of state data for vitreous and rutile-type GeO 2 . The high-pressure phase observed on the Hugoniot is most consistent with either the α-PbO 2 -type or CaCl 2 -type phase. Finally, we have compared our data on crystalline germania with existing studies on the corresponding phases of SiO 2 to better understand the effects of cation substitution on phase transformations and equations of state in Group 14 dioxides.

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A neutron diffraction investigation of the structure of vitreous germania

Cited by 70 publications

References 24 publications

Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Determination of Silica and Germania Film Network Structures on Ru(0001) at the Atomic Scale

Equation of state of theα−PbO2andPa3¯-type phases of
Dutta
¹
,
White
²
,
Greenberg
³

et al. 2018
Phys. Rev. B

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A neutron diffraction investigation of the structure of vitreous germania

Cited by 70 publications

References 24 publications

Domain Structural Transition and Structural Heterogeneity in GeO2 Glass Under Densification

Domain Structural Transition and Structural Heterogeneity in GeO2 Glass Under Densification

Determination of Silica and Germania Film Network Structures on Ru(0001) at the Atomic Scale

Equation of state of theα−PbO2andPa3¯-type phases ofDutta1, White2, Greenberg3 et al. 2018Phys. Rev. B

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Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Domain Structural Transition and Structural Heterogeneity in GeO₂ Glass Under Densification

Equation of state of theα−PbO2andPa3¯-type phases of
Dutta
¹
,
White
²
,
Greenberg
³

et al. 2018
Phys. Rev. B