Aging, Fragility and Reversibility Window in Bulk Alloy Glasses

Non-reversing relaxation enthalpies (DHnr) at glass transitions Tg(x) in the PxGexSe1-2x ternary display wide, sharp and deep global minima (~ 0) in the 0.09 < x < 0.145 range, within which Tgs become thermally reversing. In this reversibility window, glasses are found not to age, in contrast to aging observed for fragile glass compositions outside the window. Thermal reversibility and lack of aging seem to be paradigms of self-organization which molecular glasses share with protein structures which repetitively and reversibly change conformation near Tg and the folding temperature respectively.