Devitrification characteristics of GexSe1−x glasses

Azoulay, R.; Thibierge, H.; Brenac, Alain

doi:10.1016/0022-3093(75)90006-x

Cited by 179 publications

(61 citation statements)

References 11 publications

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“…To investigate this possibility, the MYEGA model (Mauro et al, 2009) FIGURE 4 | The dependence of the glass transition temperature Tg for the GexSe 1− x system, as measured using a variety of methods, on the composition x and mean coordination numbern = 2(1 + x). The results obtained from the total heat flow in the present work are compared to the results obtained by Avetikyan and Baidakov (1972), Awasthi and Sampath (2002), Azoulay et al (1975), Bhosle et al (2012a,b), Boolchand (2000), Boolchand and Bresser (2000), Bureau et al (2003), Dembovskii et al (1965), Feltz and Lippmann (1973), Feltz et al (1983), Feng et al (1997, Gueguen et al (2011), Guin et al (2002a, Gulbiten et al (2013), Lucas et al (2003), Nemilov (1964), Ota et al (1978), Sarrach et al (1976), Senapati and Varshneya (1996), Sharma et al (2005), Sreeram et al (1991a), Svoboda and Málek (2015), Wagner et al (1997), Wang et al (2005), Yang et al (2013), and Zhao et al (2013). The inset shows solely the results for Tg,rev as obtained in the present work and in the work of Boolchand and coworkers (Feng et al, 1997;Boolchand, 2000;Boolchand and Bresser, 2000;Wang et al, 2005;Bhosle et al, 2012a,b)-see Section 3.1 for details.…”

Section: Viscosity and Fragility Indexmentioning

confidence: 51%

“…FIGURE 2 | The dependence of the mass density at room temperature ρmass for the GexSe 1− x system on the composition x and mean coordination number n = 2(1 + x). The results from the present work at ≃22°C are compared to those taken from Andonov (1982), Avetikyan and Baidakov (1972), Azoulay et al (1975), Bhosle et al (2012b), Borisova (1981), Feltz et al (1983), Feltz and Lippmann (1973), Guin et al (2002b), Hafiz et al (1993), Ito et al (1988), Loehman et al (1972), Ota et al (1978), Senapati and Varshneya (1995), Sreeram et al (1991b), and Yang et al (2013). The solid (black) curves are drawn as guides for the eye.…”

Section: Glass Synthesis and Characterizationmentioning

confidence: 77%

“…The first objective of this article is to search for a structural origin of the intermediate phase by performing a set of neutron diffraction experiments on vitreous Ge x Se 1−x across the glassforming region 0 ≤ x ≤ 0.43 (Azoulay et al, 1975). The experiments used samples containing Ge and Se of natural isotopic abundance, for which the coherent neutron scattering lengths take similar values, i.e., b Ge = 8.185(20) fm and b Se = 7.970(9) fm (Sears, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Topological Ordering and Viscosity in the Glass-Forming Ge–Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase

et al. 2017

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The topological ordering of the network structure in vitreous Ge x Se 1−x was investigated across most of the glass-forming region (0 ≤ x ≤ 0.4) by using high-resolution neutron diffraction to measure the Bhatia-Thornton number-number partial structure factor. This approach gives access to the composition dependence of the mean coordination number n and correlation lengths associated with the network ordering. The thermal properties of the samples were also measured by using temperature-modulated differential scanning calorimetry. The results do not point to a structural origin of the so-called intermediate phase, which in our work is indicated for the composition range 0.175(8) ≤ x ≤ 0.235(8) by a vanishingly small non-reversing enthalpy near the glass transition. The midpoint of this range coincides with the mean-field expectation of a floppy-to-rigid transition at x = 0.20. The composition dependence of the liquid viscosity, as taken from the literature, was also investigated to look for a dynamical origin of the intermediate phase, using the Mauro-YueEllison-Gupta-Allan (MYEGA) model to estimate the viscosity at the liquidus temperature. The evidence points to a maximum in the viscosity at the liquidus temperature, and a minimum in the fragility index, for the range 0.20 ≤ x ≤ 0.22. The utility of the intermediate phase as a predictor of the material properties in network glass-forming systems is discussed.

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Section: Viscosity and Fragility Indexmentioning

confidence: 51%

Section: Glass Synthesis and Characterizationmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

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Topological Ordering and Viscosity in the Glass-Forming Ge–Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase

et al. 2017

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“…Applying the Maxwell stability criterion, isostatic glasses (n c =3) are expected to be found at the magic average coordination number [60] ofr=2.40 in 3D, corresponding usually to a non-stoichiometric composition where glass-forming tendency has been found to be optimized experimentally [259,260]. The physical origin of this stability criterion has been revealed from the vibrational analysis of bond-depleted random networks [61] constrained by bond-bending and bondstretching interactions (see equ.…”

Section: Rigidity Theory Of Network Glassesmentioning

confidence: 99%

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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“…Heat flow shift ∆H across T g was examined for its linearity vs. the scan rate q. 13) from elemental Ge and Se (5N purity, CERAC). The compositions were confirmed to ±0.2 Ge at% by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis.…”

Section: Introductionmentioning

confidence: 99%

Thermo-Kinetic Anomalies across Rigidity Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>

Awasthi

Sampath

2002

Mater. Trans.

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We have investigated the glass-transition kinetics of nine Ge x Se 1−x glasses by differential scanning calorimetry. Relation between the drive (heating-rate q) and response (heatflow shift ∆H at T g ) is seen to be strictly linear only for GeSe 4 , known to signify the bulk-rigidity threshold for this series. From an Arrhenius analysis the activation energies for glassy relaxation are estimated, and point to the existence of different thermokinetic phases below and above the threshold composition. Series behaviour of the kinetic activation is conciled to a concurring one seen in the size of cooperatively diffusing regions. The anomalies are attributed to structural crossovers with Ge doping; first from the parent uniform Se-chains to that of backbones out-branching at corner-shared Ge(Se 1/2 ) 4 tetrahedral clusters, and subsequently interconnecting by edge-shared configurations to realize a random pearl-necklace 3-D covalent network.

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Devitrification characteristics of GexSe1−x glasses

Cited by 179 publications

References 11 publications

Topological Ordering and Viscosity in the Glass-Forming Ge–Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase

Topological Ordering and Viscosity in the Glass-Forming Ge–Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase

Relaxation and physical aging in network glasses: a review

Thermo-Kinetic Anomalies across Rigidity Threshold in Ge<SUB>x</SUB>Se<SUB>1-x</SUB>

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