Melt dynamics, nature of glass transition and topological phases of equimolar GexAsxS100-2x ternary glasses

JOURNAL OF ALLOYS AND COMPOUNDS

卷:868

Article

Almutairi, Badriah S.^1,5  Chakravarty, S.²  Chbeir, R.³  Boolchand, P.³  Micoulaut, M.⁴ 

[1] Univ Cincinnati, Dept Phys, Cincinnati, OH USA

[2] Univ Cincinnati, Dept Mech & Mat Engn, Cincinnati, OH USA

[3] Univ Cincinnati, Dept Elect Engn & Comp Sci, Cincinnati, OH 45219 USA

[4] Sorbonne Univ, Lab Phys Theor Matiere Condensee, 4 Pl Jussieu, F-75252 Paris 05, France

[5] Princess Nourah Bint Abdulrahman Univ, Dept Phys, Riyadh, Saudi Arabia

关键词: Amorphous material;    Liquid solid reactions;    Optical properties;    Phase transitions;    Calorimetry;    Optical spectroscopy;   

DOI  :  10.1016/j.jallcom.2021.159101

来源: Elsevier

【 摘 要 】

The Topological Phases (TPs) in specially homogenized equimolar GexAsxS100-2x ternary glasses are established here by performing detailed Raman scattering, together with Modulated-DSC and Volumetric measurements over a wide range of compositions, 5% < x < 25%. Our results show the presence of an Intermediate Phase (IP) residing in the 9.0% < x < 16.0% range, with compositions x < 9.0% in the flexible phase, and compositions x > 16% in the stressed-rigid phase. The novel use of ex-situ Raman profiling on the entire batch of compositions indicates very slow dynamics that is tracked with time and composition and reveals the impact of homogenization on physico-chemical properties of glasses. Stressed-Rigid glasses exceeding the chemical threshold composition are all found to be nanoscale phase separated. In the presently synthesized specially homogenized melts/glasses, we observe (i) evidence for the elusive 537 cm(-1) Raman active mode of the S = As stretch in quasi-tetrahedral S = As(S-1/2)(3) local structure, (ii) a square-well like variation of the non-reversing enthalpy of relaxation Delta H-nr(x) at T-g displaying the Reversibility window and defining the Intermediate Phase (IP), (ii) a square-well like variation of molar volumes, V-m(x) coinciding with the IP composition range defining a Volumetric window, (iii) Melt fragility index, m(x), variation showing a global minimum in the IP compositions with m(x) < 20, and with the fragility index, m(x) > 20 for non-IP compositions, defining a Fragility Anomaly, and finally a variation in the specific heat jump near Tg, Delta(Cp)(x), that tracks part of the observed anomalies in m(x) and Delta H-nr(x). The location of each of these anomalies/windows coinciding with those of the IP highlights the privileged nature of the window edge compositions that represent respectively rigidity- (x(r) = 9.0%)- and the stress- (x(s) = 16.0%) elastic phase transitions determined within the Topological Constraint Theory of glasses. (C) 2021 Elsevier B.V. All rights reserved.

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