Thermally reversing window and stiffness transitions in chalcogenide glasses

Selvanathan, D.; Bresser, W. J.; Boolchand, P.; Goodman, B. A.

doi:10.1016/s0038-1098(99)00248-3

Cited by 84 publications

(87 citation statements)

References 22 publications

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“…40, identified with the location of a mean-field flexible to rigid transition 13,14 . More recent work on the Ge x Se 100−x binary has shown 4 that the fragility index M takes on a rather low value of 14.8(5) near a Ge concentration of x = 22% corresponding to a mean coordination number r = 2.44 residing in the Intermediate Phase of corresponding bulk glasses [15][16][17] where the enthalpic relaxation at the glass transition temperature is minuscule. A theoretical link between enthalpic changes, fragility and isostatic character of the glass network has been established from a simple Keating model reproducing the behavior of covalent glass-forming liquids 18 .…”

Section: Introductionmentioning

confidence: 99%

Crucial effect of melt homogenization on the fragility of non-stoichiometric chalcogenides

Ravindren

Gunasekera

Tucker

et al. 2014

The Journal of Chemical Physics

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The kinetics of homogenization of binary As x Se 100−x melts in the As concentration range 0% < x < 50% are followed in FT-Raman profiling experiments, and show that 2 gram sized melts in the middle concentration range 20% < x < 30% take nearly two weeks to homogenize when starting materials are reacted at 700 o C. In glasses of proven homogeneity, we find molar volumes to vary non-monotonically with composition, and the fragility index M displays a broad global minimum in the 20% < x < 30% range of x wherein M < 20.We show that properly homogenized samples have a lower measured fragility when compared to larger underreacted melts. The enthalpy of relaxation at T g , ∆H nr (x) shows a minimum in the 27% < x < 37% range. The super-strong nature of melt compositions in the 20% < x < 30% range suppresses melt diffusion at high temperatures leading to the slow kinetics of melt homogenization.

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Section: Introductionmentioning

confidence: 99%

Crucial effect of melt homogenization on the fragility of non-stoichiometric chalcogenides

Ravindren

Gunasekera

Tucker

et al. 2014

The Journal of Chemical Physics

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“…First, the underlying nature of the onset of rigidity in glasses has been questioned because two transitions at r c1 and r c2 have been found experimentally in binary Si-Se glasses [11]. The evidence was first presented in summer of 1998 at the Traverse City meeting on Rigity Theory and Applications [12] by Boolchand have since been observed in a variety of other binary and ternary covalent glass systems [13,14] and Fig.…”

Section: Introductionmentioning

confidence: 99%

Onset of rigidity in glasses: From random to self-organized networks

Micoulaut

Phillips

2007

Journal of Non-Crystalline Solids

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In this paper, we review the signatures of a new elastic phase that is found in glasses with selected compositions. It is shown that in contrast with random networks, where rigidity percolates at a single threshold, networks that are able to self-organize to avoid stress will remain in an almost stress-free state during a compositional interval, a Boolchand intermediate phase, that is bounded by a flexible phase and a stressed rigid phase. We report the experimental signatures and describe the theoretical efforts that have been accomplished to characterize the Boolchand intermediate phase. We illustrate one of the methods used in more detail with the example of Group III chalcogenides and finally suggest further possible experimental signatures of self-organization.

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“…Complete Raman and MDSC measurements are now available on the companion IV-VI binary glass system, Si x Se 1-x [36,37]. The results reveal strikingly parallel details of the intermediate phase in this binary glass system with x c (l) = 0.20 and x c (2) = 0.27.…”

Section: Macro-raman Scatteringmentioning

confidence: 83%

“…Although Raman scattering has been used as a probe of glass structure [32][33][34][35] for the past three decades, the application of the optical method as a probe of rigidity transitions in network glasses is a recent development [20,[36][37][38][39]. In many cases when vibrational bands are resolved, it is possible to quantitatively follow mode frequency changes with glass composition and deduce power-laws describing optical elasticity changes.…”

Section: Raman Elastic Thresholds and The Intermediate Phasementioning

confidence: 99%