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Aging of Selenium glass probed by MDSC and Raman Scattering Experiments: Growth of inter-chain structural correlations leading to network compaction

Dash, Shreeram J
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354472387536

Abstract Details

2017, MS, University of Cincinnati, Engineering and Applied Science: Materials Science.
We examine the microscopic origin of ageing in glassy Selenium using MDSC and Raman scattering experiments. For the first time, using low scan rates in MDSC, we observe a striking narrowing of Glass transition width W from 7.1(3) °C to 1.5(2) °C and an increase in the non-reversing enthalpy of relaxation (ΔHnr at Tg from 0.23(5) cal/gm to 0.90(5) cal/gm as a result of aging in the absence of light for 4 months. Both calorimetric observables (W, ΔHnr) exhibit a similar stretched exponential relaxation with aging time with a stretched exponent β = 3/7. Detailed Raman Mode analysis of g-Se in fresh state and aged for 8m show the A1 mode of Sen chains (near 250 cm-1) to narrow by 26% and a concommitant decrease in its scattering strength as the modes of correlated chains (near 235 cm-1) and A1 mode of Se8 rings (near 264 cm-1) steadily grow. These findings are viewed to come from the "molecular" chains of Sen predominant in the fresh glass reconstructing with each other, and leading to a compaction of the network due an "aging-induced growth of inter-chain correlations". Aging of pure Se glass is intrinsically tied to the flexibility of the chain network. Alloying Se with Ge leads to shortening in length of Sen chain-segments and progressive stiffening of the network, lending all chain-reconstruction effects to be supressed as the Ge alloying content increases to about 10%.
Punit Boolchand, Ph.D. (Committee Chair)
Revla Buchanan, Ph.D. (Committee Member)
Marc Cahay, Ph.D. (Committee Member)
Chad Holbrook, Ph.D. (Committee Member)
Peter Kosel, Ph.D. (Committee Member)
Vijay Vasudevan, Ph.D. (Committee Member)
78 p.
Materials Science
Glass Transition; Ageing; Modulated Differential Scanning Calorimetry; Raman Scattering; Enthalpy of Relaxation; Width of Glass Transition

Recommended Citations

Citations

  • Dash, S. J. (2017). Aging of Selenium glass probed by MDSC and Raman Scattering Experiments: Growth of inter-chain structural correlations leading to network compaction [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354472387536

    APA Style (7th edition)

  • Dash, Shreeram. Aging of Selenium glass probed by MDSC and Raman Scattering Experiments: Growth of inter-chain structural correlations leading to network compaction. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354472387536.

    MLA Style (8th edition)

  • Dash, Shreeram. "Aging of Selenium glass probed by MDSC and Raman Scattering Experiments: Growth of inter-chain structural correlations leading to network compaction." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354472387536

    Chicago Manual of Style (17th edition)

ucin1490354472387536
125
© 2017, some rights reserved.Creative Commons License Aging of Selenium glass probed by MDSC and Raman Scattering Experiments: Growth of inter-chain structural correlations leading to network compaction by Shreeram J Dash 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.