Relaxation in Ge2Se98 and As2Se98 glasses

Svoboda, Roman; Honcová, Pavla; Málek, Jiřı́

doi:10.1016/j.jnoncrysol.2009.12.014

Cited by 25 publications

(17 citation statements)

References 33 publications

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“…Note that it was shown in our previous studies, e.g. [15][16][17][18], that this type of thermal history very well represents all the features of the enthalpy relaxation phenomenon. The applied cooling rates covered almost two decades: 0.5, 1, 2, 3, 5, 7, 10, 15, 20 and 30 °C min −1 .…”

Section: Methodssupporting

confidence: 62%

Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range

Svoboda

Málek

2016

Philosophical Magazine

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Differential scanning calorimetry was used to study enthalpy relaxation kinetics of the Ge 20 Te (80-y) Se y infrared chalcogenide glasses for the compositional range y = 0-8. The relaxation behaviour was described in terms of the phenomenological Tool-NarayanaswamyMoynihan (TNM) model. The direct curve-fitting procedure was used to determine the values of TNM parameters. Compositional evolution of the TNM parameters was interpreted with respect to the involved structural entities and their motions. Based on the joint Raman scattering study, the addition of Se leads to increased amount of edgeshared GeTe 4-x Se x tetrahedra. While the primary structural basis for the relaxation movements appears not to be affected by addition of Se (constant value of non-linearity), changes of the non-exponentiality parameter indicate increased structural variability occurring within the groups of directly interlinked tetrahedra, which were found to carry the main portion of relaxation movements. Increased activation energy was explained by the presence of significantly stronger Ge-Se bonds and increased amount of edge-shared tetrahedra.

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Section: Methodssupporting

confidence: 62%

Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range

Svoboda

Málek

2016

Philosophical Magazine

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“…A combination of mercury dilatometry and DSC [162] on certain network glasses (Ge 2 Se 98 and As 2 Se 98 ) using, again, the TNM model shows that enthalpic and volumetric relaxation are nearly identical and lead to the same ∆h * value, a situation that is also met for elemental selenium. In this series of selenide network glasses, there has been a lot of attention [163,164,165,166] on the relaxation of the latter (pure Se) whose network is made of long Se chains [167].…”

Section: Applicationsmentioning

confidence: 89%

Relaxation and physical aging in network glasses: a review

Micoulaut

2016

Rep. Prog. Phys.

100

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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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“…They have pointed out that the activation energy deduced from classic and intrinsic cycles is close to that obtained from curve-fitting. Svoboda et al [14] have also studied the relaxation process in Ge 2 Se 98 and As 2 Se 98 glasses on the basis of Tool-Naraynaswamy-Moynihan equation. Saiter et al [11] have shown that a very long ageing performed at low temperature, compared to T g , leads to a reversible phase-like separation in Ge x Se 1−x vitreous system.…”

Section: Introductionmentioning

confidence: 99%

Structural relaxation due to sub-Tg annealing of Se98In1.5Sn0.5 chalcogenide glass

Imran

Al-Shawabkeh

2010

Journal of Alloys and Compounds

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Relaxation in Ge2Se98 and As2Se98 glasses

Cited by 25 publications

References 33 publications

Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range

Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range

Relaxation and physical aging in network glasses: a review

Structural relaxation due to sub-Tg annealing of Se98In1.5Sn0.5 chalcogenide glass

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Relaxation in Ge2Se98 and As2Se98 glasses

Cited by 25 publications

References 33 publications

Enthalpy relaxation kinetics of Ge20Te(80-y)Seyfar-infrared glasses in the glass transition range

Enthalpy relaxation kinetics of Ge20Te(80-y)Seyfar-infrared glasses in the glass transition range

Relaxation and physical aging in network glasses: a review

Structural relaxation due to sub-Tg annealing of Se98In1.5Sn0.5 chalcogenide glass

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Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range

Enthalpy relaxation kinetics of Ge₂₀Te_(80-y)Se_yfar-infrared glasses in the glass transition range