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SELF-ORGANIZATION AND AGING IN NETWORK GLASSES

CHAKRAVARTY, SWAPNAJIT
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054913421

Abstract Details

2003, MS, University of Cincinnati, Engineering : Computer Engineering.
Ternary P x Ge x Se 1-2x glasses in the 0 < x < 0.26 composition range, in their fresh and aged state are examined in temperature modulated DSC, Raman scattering and molar volume measurements. Bimodal endotherms are observed, with the high-T endotherm representing a glass transition temperature, while the sub-T g endotherm an activated process. We speculate that the latter is associated with P 4 units [(Se=P(Se 1/2 ) 3 )] frozen at high T converting to P 3 [(P(Se 1/2 ) 3 )] ones as the glass is heated. The sub-T g endotherm up-shifts in temperature with aging and in some cases merges with T g endotherm. T g (x) accessed from the reversing heat flow are found to increase with x as a power-law, displaying a weak cusp near x = 0.04. The non-reversing enthalpy is found to display a global minimum in the 0.09 < x < 0.145 range identified with the thermally reversing window . Raman scattering reveals that isostatically rigid units of P 3 , P 4 , CS and ES Ge(Se 1/2 ) 4 comprise building blocks of the thermally reversing window. Raman optical elasticity measurements suggest the existence of three distinct elastic phases; floppy (x < 0.09), intermediate (0.09 < x < 0.145), and stressed rigid (x > 0.145) with two distinct elastic thresholds at x = 0.084 and x = 0.1447. The elasticity power-laws in the intermediate and stressed-rigid phases are found to be p = 1.0(1) and p = 1.49(2) respectively. The coincidence of the thermal and elastic thresholds shows that the thermally reversing window represents the self-organized phase in the present ternary. Glass compositions inside (outside) the window are characterized by absence (presence) of aging of the non-reversing enthalpy as well as molar volumes . These results reinforce the privileged nature of glasses in the window that are in a state of low free energy.
Dr. Punit Boolchand (Advisor)
137 p.
chalcogenide glasses; self organization; aging; intermediate phase; phosphorus germanium selenium glasses

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Citations

  • CHAKRAVARTY, S. (2003). SELF-ORGANIZATION AND AGING IN NETWORK GLASSES [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054913421

    APA Style (7th edition)

  • CHAKRAVARTY, SWAPNAJIT. SELF-ORGANIZATION AND AGING IN NETWORK GLASSES. 2003. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054913421.

    MLA Style (8th edition)

  • CHAKRAVARTY, SWAPNAJIT. "SELF-ORGANIZATION AND AGING IN NETWORK GLASSES." Master's thesis, University of Cincinnati, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1054913421

    Chicago Manual of Style (17th edition)

ucin1054913421
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© 2003, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.