Relaxation Dynamics in Selenide-Based Chalcogenide Glasses: Characterization of the Intermediate Phase

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In this project funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Chemistry Division, Sindee L. Simon and Gregory B. McKenna of Texas Tech University will investigate the relaxation dynamics in selenide-based chalcogenide glasses using calorimetry, dynamic heat spectroscopy, shear and bulk rheology, and nanorheology. Three important scientific issues are addressed: the stability of the glasses with respect to aging near and in the intermediate phase region, the effects of nanoconfinement and pressure on the dynamics, and the origin of the unusual mechanical stiffening of ultrathin films. Of particular interest is the measurement of enthalpy recovery and creep during aging as a function of composition, temperature, and aging time aimed at a more complete understanding of the composition dependence of the stability of these glasses. Broader impacts include training of two graduate students, incorporation of new material into courses taught by the PIs, and outreach to young students, from fifth through eleventh grades, through a "Super Saturdays" enrichment program for grade-school children and a summer "Science - It's a Girl Thing" program for junior-high and high-school girls.The physical and chemical stability of chalcogenide glasses are important in many of their potential applications, including as memory devices, optical waveguides, and solar cells. By increasing understanding the Boolchand intermediate phase, which has enhanced stability, the results are anticipated to facilitate synthesis of stable chalcogenide glasses for such applications.