Copper (I) and silver (I) oxides crystallize with the same structure, and both show a wide range of negative thermal expansion (NTE): Cu2O contracts with temperature up to about 200 K and then expands, while Ag2O has a NTE up to its decomposition temperature at about 450 K. Here we report a careful temperature-dependent pair distribution function (PDF) analysis that showed that copper oxide, at about 200 K, exhibits geometric distortions of the tetrahedral units, probably related to a change in the solid angle of the polyhedra. Silver oxide, on the other hand, showed the same distortions even at the lowest temperature measured (10 K): structural refinements of the PDF confirmed the presence of local distortions (below 10 Å) at all temperatures.
|Titolo:||Study of the negative thermal expansion of cuprite-type structures by means of temperature-dependent pair distribution function analysis : Preliminary results|
DAPIAGGI, MONICA (Primo)
|Parole Chiave:||A. oxides; C. Neutron scattering; D. Thermal expansion|
|Settore Scientifico Disciplinare:||Settore GEO/06 - Mineralogia|
|Data di pubblicazione:||2008|
|Digital Object Identifier (DOI):||10.1016/j.jpcs.2008.03.030|
|Appare nelle tipologie:||01 - Articolo su periodico|