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EnglishExtended x-ray absorption fine structure has been measured at the K edge of copper in CuScO(2) and CuLaO(2) to investigate the local origin of negative thermal expansion (NTE) along the c axis. A positive expansion of the Cu-O bond has been measured within the entire temperature interval to be contrasted with the negative expansion of the distance between average atomic positions measured by diffraction; the inadequacy of the riding correction to diffraction data has been evidenced. The weak temperature dependence of the parallel mean-square relative displacement (MSRD) indicates a rather stiff Cu-O bond, while the large perpendicular MSRD measures an intense relative motion of copper with respect to oxygen atoms perpendicular to the c axis. The comparison between the two compounds enlightens the relevance of the correlation of perpendicular motion to quantitatively explain the apparent NTE of the Cu-O bond.
| Titolo: | Negative thermal expansion in crystals with the delafossite structure: An extended x-ray absorption fine structure study of CuScO(2) and CuLaO(2) |
| Autori: | Ahmed, Sofia; Dalba, Giuseppe; Fornasini, Paolo; Vaccari, Marco; Rocca, Francesco; Sanson, Andrea; J., Li; A. W., Sleight |
| Autori Unitn: | |
| Titolo del periodico: | PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS |
| Anno di pubblicazione: | 2009 |
| Numero e parte del fascicolo: | 10 |
| Codice identificativo Scopus: | 2-s2.0-64149131629 |
| Codice identificativo ISI: | WOS:000264768600052 |
| Digital Object Identifier (DOI): | 10.1103/PhysRevB.79.104302 |
| Handle: | http://hdl.handle.net/11572/90745 |
| Appare nelle tipologie: | 03.1 Articolo su rivista (Journal article) |
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