@article{1175,
  keywords = {Invited},
  author = {Cronin Vining},
  title = {Materials science: Half-full glasses},
  abstract = {The low thermal conductivity of some thermoelectric materials is commonly attributed torattlers — atoms trapped in oversized cages. Two independent studies now show that rattlersindeed reduce thermal conductivity to glass-like values.Thermoelectric devices transformthermal gradients into electric voltageand vice versa. Th ey may be used oneday in vehicles to improve the fuel effi ciencyby generating electricity from waste heat.In the Peltier cooling mode, they may alsohave a role in replacing the most commonair-conditioning refrigerant (R-134a), aworse greenhouse gas than carbon dioxide.To obtain high effi ciency, thermoelectricmaterials need a high electrical conductivityand low thermal conductivity. Particularlygood thermoelectric properties are exhibitedby the classes of fi lled skutterudites andclathrates. In these compounds, looselybonded atoms fi lling the cages of the originalstructure are colourfully known as ‘rattlers’(see Fig. 1), and they are believed to give riseto low, glass-like thermal conductivity. Inthis issue, inelastic neutron scattering studiesby Koza et al.1 on skutterudites (page XXX)and by Christensen et al.2 on clathrates(page YYY) clarify the so-called ‘phononglass–electron crystal’ (PGEC)3 and rattler4concepts, popular strategies for improvingthermoelectric energy-conversion effi ciency.Interestingly, each study addresses whetherthe rattlers rattle and whether the phononsare glass-like, but they hold diff erent viewsof what ‘glass-like’ means.},
  year = {2008},
  journal = {Nature Materials},
  volume = {7},
  pages = {765-766, },
  month = {2008///},
  url = {http://cvining.com/system/files/articles/vining/Vining-Nature-2008b.pdf},
  doi = {10.1038/nmat2271},
  language = {eng},
}