Glass - Back to the Future!



Presenting Author:
C. Austen Angell
<caa@asu.edu>

article posted 21 March 2016


Charles Austen Angell is one of the Regentsí Professors at Arizona State University (ASU). He holds B.Sc. and M.Sc. degrees from the University of Melbourne, Australia, and a Ph.D. degree from Imperial College London. After a postdoctoral position at Argonne National Laboratory, he joined Purdue University where he became full professor in 1971. In 1989 he moved to ASU. His research interests lie mainly in supercooled liquids and glasses, particularly water and ionic liquids, but he also works on batteries and fuel cells. He has authored some 520 research papers and reviews, nearly 100 of which have been cited over 100x (Google scholar). His work has been honored by awards from four different Technical Societies - ACERS (1991, Morey), ACS (2004, Hildebrand), MRS (2006,Turnbull) and ECS (2010, Bredig). He is proud of an "Outstanding Reviewer Award" from the American Physical Society (2011)






New twists on the path to understanding the glass transition and the ultimate fate of supercooling liquids

C. Austen Angell
School of Molecular Sciences, Arizona State University, Tempe, AZ 85287-1604, USA



Glass transitions are usually thought to be the province of supercooling liquids which fail to crystallize, but this description in a number of ways underrates their importance to condensed matter physics. Firstly, some of the most interesting glass transitions occur in phases that have never "seen" the liquid state until they pass through the glass transition during heating, and others never see it at all, if we allow the term "glass transition", to refer to the breaking and restoring of ergodicity in a condensed phase of interest. In this talk we will use data on a glass transition of the latter type which occurs in the cooling and reheating of a simple system comprising two similar metal atoms, Co and Fe in a 1:1 mixture, to provide an easily understood example of a glass transition in a system in which both the kinetics and excitation thermodynamics lie at the "strong" extreme of the "strong-fragile" spectrum of liquid-formed glass behavior and the glass transition is the precursor to a lambda transition (critical point of the Ising class) at higher temperatures. From this starting point we then consider the relation between glass transition behavior of inorganic (SiO2, BeF2) and molecular (H2O) network glasses, and then their mixtures with ideal solution-forming second components. This provides a common basis for the observed precipitation from alkali silicates of almost pure SiO2, on the one hand, and first order transformation of aqueous solutions to almost pure low density amorphous water, on the other.