The Ge–Ô–Ge bond angle distribution in GeO2 glass: a NMR determination

Hussin, Rosli; Dupree, Ray; Holland, Diane

doi:10.1016/s0022-3093(99)00090-3

Cited by 64 publications

(65 citation statements)

References 47 publications

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“…Such tetrahedral structures are assumed to be preserved in GeO 2 -GeS 2 glasses. A marked quantitative difference between these two glasses is the bond angles of 130°in GeO 2 [22], and 80°and 100°in GeS 2 [20] at Ge-O(S)-Ge, which are consistent with the present RDF in Fig. 4.…”

Section: Discussionsupporting

confidence: 89%

“…A comparison of the results for x = 0, 30, and 100 suggests the shortening of the bond distance from Ge-S to Ge-O. However, the shift in the second peak is relatively small, which probably reflects the distance shortening and a bond-angle widening from the sulfide to the oxide [20,22]. On the other hand, in the brown sample with x = 30, the first peak also shifts to a smaller distance, while the second peak shifts slightly to a longer distance with decreasing intensity.…”

Section: X-ray Diffraction and Rdfsmentioning

confidence: 93%

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The structure and optical properties of GeO2–GeS2 glasses

Terakado

Tanaka

2008

Journal of Non-Crystalline Solids

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Section: Discussionsupporting

confidence: 89%

Section: X-ray Diffraction and Rdfsmentioning

confidence: 93%

The structure and optical properties of GeO2–GeS2 glasses

Terakado

Tanaka

2008

Journal of Non-Crystalline Solids

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“…From this simple example (As 2 Se 3 ), one determines r As = 3 and r Se = 2 leading to 1.5 and 1 BS constraints, a result that is expected from a constraint count based solely on the 8-N rule [61,253], N being the number of s and p electrons. However, for certain systems for which this rule does not apply (telluride network glasses, see below) or in densified systems with o , close to the value obtained from experiments [312]. All other angles display broad variations and correspond to angles defined by next-nearest neighbor shells.…”

Section: Bond-stretchingsupporting

confidence: 77%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

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Abstract. Recent progresses in the description of glassy relaxation and ageing are reviewed for the wide class of network-forming materials such as GeO 2 , Ge x Se 1−x , silicates (SiO 2 -Na 2 O) or borates (B 2 O 3 -Li 2 O), all of them having 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 aspect 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 to calculate various structure-related functions in connection with glassy relaxation and the physics of ageing which reveals the off-equilibrium nature of glasses. We discuss the notion of spatial variations of structure which leads to the picture of "dynamic heterogeneities", and recent results of this important topic for network glasses are also reviewed.PACS numbers: 61.43. Fs, 64.70.kj Relaxation and physical ageing in network glasses 2 Figure 1. Typical network-forming glasses: a) A stoichiometric glass former (SiO 2 , B 2 S 3 ) whose structure and network connectivity can be altered by the addition (b) of 2-fold coordinated atoms (usually chalcogens, S, Se) that lead to cross-linked chains. The structure can also be depolymerized (c) by the addition of a network modifier (alkali oxides or chalcogenides, Na 2 O, Li 2 S, etc.). Glassy dynamics depends strongly on the network topology, i.e. the way bonds and angles arrange to lead to a connected atomic network. Note that only chalcogenides can produce a mixture of these three kinds of basic networks, e.g. (1-x)Ge y Se 1−y -xAg 2 Se [2], and for the latter system x=0 corresponds to case (b), y=33% corresponds to case (c), and both conditions together (x=0,y=33 %) to case (a).

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“…We then see that, with the pulse exposure, the Ge-O distance may slightly decrease, while the Ge-O-Ge distance tends to become longer from $0.32 to $0.34 nm. These changes suggest that, on the average, the Ge-O-Ge bond angle increases from $125°to $140°, which are comparable with that (130°-135°) in GeO 2 glass [23][24][25]. In addition, a shoulder at $0.28 nm appears in the irradiated state, which can be ascribed to the distance between O atoms, $0.285 nm [23,24], in O-Ge-O units.…”

Section: Microscopicmentioning

confidence: 91%