Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session P58: Disordered and Glassy Systems II
2:30 PM–5:30 PM,
Wednesday, March 6, 2019
BCEC
Room: 257A
Sponsoring
Unit:
GSOFT
Chair: Elijah Flenner, Colorado State Univ
Abstract: P58.00011 : Observation of a sharp reversibility window in rejuvenated homogenized equimolar GexAsxS100-2x bulk glasses*
4:30 PM–4:42 PM
Presenter:
Badriah Almutairi
(University of Cincinnati)
Authors:
Badriah Almutairi
(University of Cincinnati)
Ralph Chbeir
(University of Cincinnati)
Soumendu Chakravarty
(University of Cincinnati)
L.C.R. Wijewardhana
(University of Cincinnati)
Punit Boolchand
(University of Cincinnati)
We have synthesized 1.5-gram sized batches of the title glasses over a wide composition range 2% ≤ x ≤ 25%, taking special care to alloy the starting materials for an extended period (several weeks) in evacuated quartz tubes, and recording FT Raman spectra along the length of the melt column till the spectra became identical. Using Modulated DSC, we then examined calorimetric properties, Tg (x), ΔCp , and ΔHnr (x), and find Tg(x) to increase monotonically with x, and the enthalpy of relaxation, ΔHnr (x) to display a sharp square-well like reversibility window with an onset near x =9.0(5)% (rigidity transition) and an endpoint x = 16.0(5)% (stress transition) in rejuvenated glasses. In FT- Raman scattering we observe modes of Ge-centered CS and ES tetrahedra and the As-centered Pyramidal and Quasi-Tetrahedral units besides modes of S8 rings and polymeric Sn chains. The mode near 537 cm-1 due to S=As(S1/2) QT units is observed in FT-Raman but not in dispersive Raman using 514 nm excitation. Complex Cp measurements using MDSC are being undertaken to establish variation in melt fragility index.
1. Tao Qu and P. Boolchand Phil. Mag B 85, 875(2005).
*
Supported by NSF grant DMR-08-53957, and Princess Nora University, Riyadh, KSA
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