Heat capacity and thermodynamic properties of GeSe2at temperatures fromT=( 13 to 900)K. Structural phase transition atT= 423K

Stølen, Svein; Johnsen, H.-B.; Abe, Rika; Ataké, Tooru; Grande, Tor

doi:10.1006/jcht.1998.0460

Cited by 9 publications

(5 citation statements)

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“…For x < 0.20 the heat capacity of the liquid Se-rich alloys all superimpose on the same master curve, defined by the heat capacity of liquid Se. 14 The heat capacity of liquid Se decreases with increasing temperature from 40 J K À1 mol À1 at the glass transition temperature to a minimum of about 34 J K À1 mol À1 at 750 K. The heat capacity of crystalline and glassy GeSe 2 11,15 behave differently. The difference between the heat capacity of supercooled liquid and crystalline GeSe 2 (excess heat capacity) at the glass transition temperature is 39 J K À1 mol À1 .…”

Section: Resultsmentioning

confidence: 99%

“…The data are derived from the heat capacity given in Fig. 1 combined with earlier low temperature data for crystalline and glassy GeSe 2 11,15 and Se. 14,34 Although the entropy of the melt varies continuously with composition, the entropy of supercooled GeSe 2 increases faster with temperature than the entropy of the Se-rich melts.…”

Section: Resultsmentioning

confidence: 99%

“…The excess heat capacity of liquid GeSe 2 is determined by differential scanning calorimetry (accuracy 2%) using crystalline GeSe 2 as a reference material. 11 The remaining heat capacity data are obtained using a step-wise heated adiabatic calorimeter. 12,13 The samples were contained in evacuated and sealed vitreous silica containers during measurement.…”

Section: Methodsmentioning

confidence: 99%

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Fragility transition in GeSe2–Se liquids

Stølen

Grande

Johnsen

2002

Phys. Chem. Chem. Phys.

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The heat capacity and entropy of liquids in the GeSe 2 -Se system are reported. The thermodynamics of the system is evaluated and discussed in light of earlier reported viscosities and recent structural studies of liquid GeSe 2 . The thermodynamics of liquid GeSe 2 suggest that extensive structural disordering takes place in the liquid on heating and points to a fragile melt at high temperatures whereas the thermodynamic characteristics of the system close to the glass transition temperature suggests a much less fragile character. A consistent picture is evident from earlier viscosity data; the viscosity of GeSe 2 -Se glasses just above T g supports a fragility minimum near x ¼ 0.225, (x is x in Ge x Se 1Àx ) while a monotonically increasing fragility is evident from the viscosity in the stable liquid and non-viscous region. We propose that the above discrepancy between the behaviour of the melts close to T g and at high temperatures can be explained by a fragile-to-strong transition in supercooled GeSe 2 -Se. The transition is related to the onset of chemical disorder and the density minimum of GeSe 2 . The proposed fragile-to-strong transition of other tetrahedral liquids has also been linked to a first order liquidliquid transition, which recently also have been discussed for GeSe 2 .

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Fragility transition in GeSe2–Se liquids

Stølen

Grande

Johnsen

2002

Phys. Chem. Chem. Phys.

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“…The invariant point is the physical condition where the further addition of MOS does not result in a decline of NaCl concentration via solvent-induced crystallization of salt (SLE). 47,48 Likewise, further addition of NaCl does not result in MOS concentration decline via salt-induced displacement of MOS (LLE). 47,48 In contrast, the dioxane mixtures do not display a salt-induced LLE despite having a lower dielectric constant than MeCN ( i.e.…”

Section: Resultsmentioning

confidence: 99%

“…47,48 Likewise, further addition of NaCl does not result in MOS concentration decline via salt-induced displacement of MOS (LLE). 47,48 In contrast, the dioxane mixtures do not display a salt-induced LLE despite having a lower dielectric constant than MeCN ( i.e. , ε of 2.1 vs. 36.6).…”

Section: Resultsmentioning

confidence: 99%