|Title||Physical vapor deposition as a route to hidden amorphous states|
|Publication Type||Journal Article|
|Year of Publication||2009|
|Authors||Dawson, K. J., K. L. Kearns, L. Yu, W. Steffen, and M. D. Ediger|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Keywords||DYNAMICS, 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|
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.
|Alternate Journal||Proc. Natl. Acad. Sci. U. S. A.|