INSTITUTO DE FISICA LA PLATA
Unidad Ejecutora - UE
congresos y reuniones científicas
Anomalous Debye temperature of metallic capped Pt nanoparticles.
GIOVANETTI, L.; RAMALLO-LÓPEZ, J. M.; REQUEJO, F. G.; CRAIEVICH A.F.; YACAMÁN, M. J.; D. GARCÍA-GUTIERREZ
LNLS, Campinas, SP, Brazil.
Congreso; 16ª Reunião Anual de Usuários; 2006
The Debye temperature (ΘD) of capped Pt nanoparticles (NPs), with an average diameter of ~ 3 nm was measured from extended X-ray absorption fine structure (EXAFS) measurements at 20-373 K. The size distribution of the NPs was determined by high resolution transmission electron microscopy (HRTEM), high-angle annular dark field (HAADF) and small angle X-ray scattering (SAXS). We have experimentally established for the first time that the ΘD of polyhedric, nearly spherical, Pt NPs is 70 K higher than that of bulk Pt metal. This rather high value of ΘD reflects strong surface effects and evidences that the thermodynamic behavior of nanostructured materials differs markedly from that of materials in bulk form.