Physical vapor deposition as a route to hidden amorphous states

TitlePhysical vapor deposition as a route to hidden amorphous states
Publication TypeJournal Article
Year of Publication2009
AuthorsDawson, K. J., K. L. Kearns, L. Yu, W. Steffen, and M. D. Ediger
JournalProceedings of the National Academy of Sciences of the United States of America
Volume106
Pagination15165-15170
ISBN Number0027-8424
Accession NumberWOS:000269632400016
KeywordsDYNAMICS, ENERGY LANDSCAPE, entropy, FREE-VOLUME, glass, GLASS-FORMING LIQUIDS, INDOMETHACIN POLYMORPHS, liquid-liquid transition, PHASE, POLYMER MELTS, SUPERCOOLED, SUPERCOOLED LIQUIDS, TEMPERATURE, TRANSITION, X-ray scattering
Abstract

Stable glasses of indomethacin (IMC) were prepared by using physical vapor deposition. Wide-angle X-ray scattering measurements were performed to characterize the average local structure. IMC glasses prepared at a substrate temperature of 0.84 T(g) (where T(g) is the glass transition temperature) and a deposition rate of 0.2 nm/s show a broad, high-intensity peak at low q values that is not present in the supercooled liquid or melt-quenched glasses. When annealed slightly above T(g), the new WAXS pattern transforms into the melt-quenched glass pattern, but only after very long annealing times. For a series of samples prepared at the lowest deposition rate, the new local packing arrangement is present only for deposition temperatures below T(g) - 20 K, suggesting an underlying first-order liquid-to-liquid phase transition.

DOI10.1073/pnas.0901469106
Alternate JournalProc. Natl. Acad. Sci. U. S. A.