Inamori School of Engineering
Conferences and Lectures - Samuel R. Scholes Lecturer

Dr. C. Austen Angell
School of Molecular Sciences
Arizona State University

Thursday, April 7, 2017
Holmes Auditorium, Harder Hall
11:20 am

Dr. Austen Angell is one of the Regents’ 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, and occasionally biomolecules. He has authored some 530 research papers and reviews, over 100 of which have been cited over 100x (Google Scholar Hindex = 101)). 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). In 1999 a special issue of J. Phys. Chem. was dedicated to his efforts in Science. He is proud of an "Outstanding Reviewer Award" from the Amer. Phys. Soc. (2011).

Fundamental aspects of supercooled liquids and the glass transition

C. Austen Angell
School of Molecular Sciences
Arizona State University

This lecture will borrow heavily from my Bragg Lecture of 2015 at University College London where I used the title The Nature of glass and the glass transition: old puzzles and the many new twists. Physics Nobel Laureate (1977) P. W. Anderson, famously stated in 1995 that "the most interesting and important unsolved problem in condensed matter physics was the nature of glass and the glass transition". He expected it to be resolved in the next decade, which has proven quite incorrect. Indeed, there have been some further major new twists added since that time.

In this lecture we explain the "old puzzles" of the liquid-to-glass transition and the complications recently introduced by "new twist" observations such as direct crystal-to-glass transitions, and liquid-to-glass transitions that appear to be thermodynamically of first order - and most recently a striking development from the Ediger group, which deserves additional attention. It is the formation of glasses by a vapor deposition route that produces glasses in energy states that would take a million years of annealing to produce by the normal liquid cooling route to stabilized glass formation.

We explain how the Ediger group discovery could be the glassy state equivalent of Suga's famous 1982 discovery of how ice Ih can be induced to give up its celebrated Pauling residual entropy and become (more or less) a respectable 3rd law substance. In the new development, the excess entropy of the glass that is formed in the normal way (by cooling of the liquid), is found to largely disappear when the glass is formed by an alternative vapor-deposition route, in which the substrate temperature for the deposit is "tuned" systematically to be about 15% below the normal Tg. In these "ultrastable" glasses, the other formerly "ubiquitous" signals of the glassy state of matter, such as the cryogenic anomalies ("tunneling states"), which were part-basis of Anderson's Nobel prize award, also disappear. Evidently the "ideal" or "perfect" glass state is being approached, just as the perfect ice crystal was being approached in the Suga experiment. We give a brief account of how this could be understood, using the Poole "modified van der Waals model" of anomalous liquids, and (time permitting), link it to the phenomenology governing the "phase change" materials that are currently under development for next generation rewritable digital memory systems.