Abstract
| Original language | English |
|---|---|
| Article number | 32 |
| Number of pages | 15 |
| Journal | Frontiers in Materials |
| Volume | 4 |
| Issue number | 32 |
| DOIs | |
| Publication status | Published - 13 Nov 2017 |
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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. / Zeidler, Anita; Salmon, Philip; Whittaker, Dean; Pizzey, Keiron; Hannon, Alex C.
In: Frontiers in Materials, Vol. 4, No. 32, 32, 13.11.2017.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Topological Ordering and Viscosity in the Glass-Forming Ge-Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase
AU - Zeidler, Anita
AU - Salmon, Philip
AU - Whittaker, Dean
AU - Pizzey, Keiron
AU - Hannon, Alex C
PY - 2017/11/13
Y1 - 2017/11/13
N2 - The topological ordering of the network structure in vitreous GexSe1-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-Yue-Ellison-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.
AB - The topological ordering of the network structure in vitreous GexSe1-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-Yue-Ellison-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.
UR - https://www.frontiersin.org/articles/10.3389/fmats.2017.00032/abstract
UR - http://doi.org/10.3389/fmats.2017.00032
U2 - 10.3389/fmats.2017.00032
DO - 10.3389/fmats.2017.00032
M3 - Article
VL - 4
JO - Frontiers in Materials
JF - Frontiers in Materials
SN - 2296-8016
IS - 32
M1 - 32
ER -