http://www.cnr.it/ontology/cnr/individuo/prodotto/ID807
Negative thermal expansion and local dynamics in Cu2O and Ag2O (Articolo in rivista)
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- Label
- Negative thermal expansion and local dynamics in Cu2O and Ag2O (Articolo in rivista) (literal)
- Anno
- 2006-01-01T00:00:00+01:00 (literal)
- Alternative label
Sanson, A; Rocca, F; Dalba, G; Fornasini, P; Grisenti, R; Dapiaggi, M; Artioli, G (2006)
Negative thermal expansion and local dynamics in Cu2O and Ag2O
(literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
- Sanson, A; Rocca, F; Dalba, G; Fornasini, P; Grisenti, R; Dapiaggi, M; Artioli, G (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
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- ISI Web of Science (WOS) (literal)
- Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
- CNR, Ist Foton & Nanotecnol, IFN, Sez CeFSA Trento, I-38050 Trento, Italy; Univ Trent, Ist Nazl Fis Mat, I-38050 Trento, Italy; Univ Trent, Dipartimento Fis, I-38050 Trento, Italy; Univ Milan, Dipartimento Sci Terra Ardito Desio, I-20133 Milan, Italy (literal)
- Titolo
- Negative thermal expansion and local dynamics in Cu2O and Ag2O (literal)
- Abstract
- High-resolution x-ray powder diffraction and extended x-ray-absorption fine-structure (EXAFS) measurements have been performed on the iso-structural framework crystals Cu2O and Ag2O as a function of temperature. According to diffraction, both compounds exhibit a negative thermal expansion (NTE) of the lattice parameter over extended temperature intervals (from 9 to 240 K for Cu2O, up to 470 K for Ag2O) and anisotropic thermal displacements of M atoms (M=Cu,Ag). EXAFS measures a positive expansion of the nearest-neighbors M-O pair distance and a perpendicular to parallel anisotropy of relative motion, much stronger than the anisotropy of the absolute M motion. The M-O bond is much stiffer against stretching than against bending. According to EXAFS, out of the 12 M-M next-nearest-neighbor pairs, the 6 connected via a bridging oxygen undergo negative expansion, while the 6 lacking the bridging oxygen undergo positive expansion. These results show a rather complex local behavior, which, while confirming the connection of NTE to strong perpendicular vibrations, is inconsistent with rigid unit modes models and suggests a more flexible model based on rigid M-O rods. (literal)
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