Separating the configurational and vibrational entropy contributions in metallic glasses. Smith, H. L, Li, C. W, Hoff, A., Garrett, G. R, Kim, D. S, Yang, F. C, Lucas, M. S, Swan-Wood, T., Lin, J Y Y, Stone, M B, Abernathy, D L, Demetriou, M. D, & Fultz, B Nat. Phys., 13(9):900–905, Nature Publishing Group, May, 2017.
abstract   bibtex   
Glassy materials exist in nature and play a critical role in technology, but key differences between the glass, liquid and crystalline phases are not well understood. Over several decades there has been controversy about the specific heat absorbed as a glass transforms to a liquid—does this originate from vibrational entropy or configurational entropy? Here we report direct in situ measurements of the vibrational spectra of strong and fragile metallic glasses in the glass, liquid and crystalline phases. For both types of material, the measured vibrational entropies of the glass and liquid show a tiny excess over the crystal, representing less than 5% of the total excess entropy measured with step calorimetry. These results reveal that the excess entropy of metallic glasses is almost entirely configurational in origin, consistent with the early theories of Gibbs and co-workers describing the glass transition as a purely configurational transition. When a glass transforms into a liquid, is the absorbed specific heat vibrational or configurational in origin? Vibrational spectroscopy experiments on strong and fragile metallic glasses now strongly suggest the latter.
@ARTICLE{Smith2017-cp,
  title     = "{Separating the configurational and vibrational entropy
               contributions in metallic glasses}",
  author    = "Smith, Hillary L and Li, Chen W and Hoff, Andrew and Garrett,
               Glenn R and Kim, Dennis S and Yang, Fred C and Lucas, Matthew S
               and Swan-Wood, Tabitha and Lin, J Y Y and Stone, M B and
               Abernathy, D L and Demetriou, Marios D and Fultz, B",
  abstract  = "Glassy materials exist in nature and play a critical role in
               technology, but key differences between the glass, liquid and
               crystalline phases are not well understood. Over several decades
               there has been controversy about the specific heat absorbed as a
               glass transforms to a liquid---does this originate from
               vibrational entropy or configurational entropy? Here we report
               direct in situ measurements of the vibrational spectra of strong
               and fragile metallic glasses in the glass, liquid and
               crystalline phases. For both types of material, the measured
               vibrational entropies of the glass and liquid show a tiny excess
               over the crystal, representing less than 5\% of the total excess
               entropy measured with step calorimetry. These results reveal
               that the excess entropy of metallic glasses is almost entirely
               configurational in origin, consistent with the early theories of
               Gibbs and co-workers describing the glass transition as a purely
               configurational transition. When a glass transforms into a
               liquid, is the absorbed specific heat vibrational or
               configurational in origin? Vibrational spectroscopy experiments
               on strong and fragile metallic glasses now strongly suggest the
               latter.",
  journal   = "Nat. Phys.",
  publisher = "Nature Publishing Group",
  volume    =  13,
  number    =  9,
  pages     = "900--905",
  month     =  may,
  year      =  2017,
  keywords  = "MyPapers (D.S. Kim);B.T. Futlz",
  language  = "en"
}

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