Skip to Main Content
Frequently Asked Questions
Submit an ETD
Global Search Box
Need Help?
Keyword Search
Participating Institutions
Advanced Search
School Logo
Files
File List
38266.pdf (5.42 MB)
ETD Abstract Container
Abstract Header
Correlating Melt Dynamics and Configurational Entropy Change with Topological Phases of As
x
S
100-x
Glasses and the Crucial Role of Melt/Glass Homogenization
Author Info
Chakravarty, Soumendu
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623241710778164
Abstract Details
Year and Degree
2021, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
Abstract
Glass topological phases and melt dynamics of especially dry and homogeneous binary As
x
S
100-x
melts/glasses are studied in Raman scattering, Modulated-DSC and volumetric experiments. In the S-rich glasses (12% < x < 23%), unambiguous and direct evidence for the elusive 537 cm
-1
stretch vibrational mode of the Quasi-Tetrahedral (QT), S=As(S
1/2
)
3
, local structure is observed in Fourier Transform-Raman (FT-Raman) scattering once the melts homogenized and the glasses cycled through T
g
+10°C for an extended period. The enthalpy of relaxation at T
g
, ?H
nr
(x), fragility index, m(x), Molar volumes V
m
(x) – each display three distinct regime of variation. Specifically, ?H
nr
(x) shows an abrupt square-well like variation (Reversibility window), and m(x) shows a Gaussian like global minimum (Fragility window) whereas V
m
(x) shows a Gaussian-like local minimum (Volumetric window) in the isostatically rigid phase (22.5% < x < 28.5%). At low x (< 20%) in the Flexible phase, glasses are segregated with a S
8
-rich nanophase that decouples from the As-S glassy backbone. At medium x (22.5% < x < 28.5%) glassy backbones form an isostatically rigid phase displaying a vanishing ?H
nr
(x) term, and compacted structures with corresponding melts being super-strong (m < 20). At high x (28.5% < x < 40%) in the Stressed-Rigid phase, glasses possess an increasing ?H
nr
(x) term, and melts become increasingly fragile, with m(x) > 20 as x increases. Taken together, these results demonstrate that super-strong melts yield isostatically rigid glasses, while fragile glasses form either Flexible or Stressed-Rigid upon cooling. The onset of the rigidity transition near <r> = 2.22 instead of the usual value of <r> = 2.40, is identified with the presence of QT local units in addition to pyramidal As(S
1/2
)
3
local units in the glassy backbone, and with a small but finite fraction of polymeric S
n
chains being decoupled from the backbone.
Committee
Punit Boolchand, Ph.D. (Committee Chair)
Marc Cahay, Ph.D. (Committee Member)
Jude Iroh, Ph.D. (Committee Member)
Vijay Vasudevan, Ph.D. (Committee Member)
Pages
111 p.
Subject Headings
Materials Science
Keywords
Modulated Differential Scanning Calorimeter MDSC
;
Raman
;
Molar Volume
;
Topological Constraint Theory
;
Configurational Entropy
Recommended Citations
Refworks
EndNote
RIS
Mendeley
Citations
Chakravarty, S. (2021).
Correlating Melt Dynamics and Configurational Entropy Change with Topological Phases of As
x
S
100-x
Glasses and the Crucial Role of Melt/Glass Homogenization
[Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623241710778164
APA Style (7th edition)
Chakravarty, Soumendu.
Correlating Melt Dynamics and Configurational Entropy Change with Topological Phases of As
x
S
100-x
Glasses and the Crucial Role of Melt/Glass Homogenization.
2021. University of Cincinnati, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623241710778164.
MLA Style (8th edition)
Chakravarty, Soumendu. "Correlating Melt Dynamics and Configurational Entropy Change with Topological Phases of As
x
S
100-x
Glasses and the Crucial Role of Melt/Glass Homogenization." Doctoral dissertation, University of Cincinnati, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1623241710778164
Chicago Manual of Style (17th edition)
Abstract Footer
Document number:
ucin1623241710778164
Download Count:
57
Copyright Info
© 2021, some rights reserved.
Correlating Melt Dynamics and Configurational Entropy Change with Topological Phases of As
x
S
100-x
Glasses and the Crucial Role of Melt/Glass Homogenization by Soumendu Chakravarty is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Based on a work at etd.ohiolink.edu.
This open access ETD is published by University of Cincinnati and OhioLINK.