XAFS study of the thermal behaviour of gold bulk and clusters

Size dependence of the lattice parameters of carbon supported platinum nanoparticles: X-ray diffraction analysis and theoretical considerations

“…Actually, this approach which is based on the Laplace pressure can be confronted by various problems, despite its correct description of the reduction of the lattice parameter observed experimentally for Ag, 5,6,23 Pd 10,26 and Au nanoparticles. 25,65 For example, if the Laplace pressure compresses nanoparticles, the observed external pressure for a phase transition in nanoparticles should be smaller than for bulk samples and the general rule, stemmed from the above model, seems to be as follows: the smaller the nanoparticles, the lower the transformation pressure. However, the experimental size evolution for the pressure-induced g-Fe 2 O 3 (maghemite) to Fe 2 O 3 (hematite) transition showed that 7 nm nanocrystals transform at 27 GPa, 5 nm ones at 34 GPa, and to 3 nm ones at 37 GPa, 66 i.e.…”

Contactless Scanning Near‐Field Optical Dilatometry Imaging at the Nanoscale

“…From panels e‐h, we estimate the average volumetric TEC of Au to be (51.35 ± 6.89)×10 −6 K −1 with an average linear TEC of (17.12 ± 2.30)×10 −6 K −1 , and uncertainties determined by the standard deviation from all the measured ω. Comparison of these values with the TEC for Au recorded by macroscopic dilatometry techniques from the literature [ 40–53 ] is reported in Table 1 . In addition, the TEC of the same nanogranular Au thin film probed by SNOD was also measured macroscopically using an optical dilatometer (see Supporting Information), and comparable TEC estimates were obtained.…”

“…In principle, thermal expansivity information with higher resolution can be obtained by measuring the changes in the crystallographic lattice sites with x-ray spectroscopy where the measured spectra are accompanied with a thermodynamical interpretation involving anharmonic effects to determine the thermal expansion. [12][13][14] These methods are also macroscopic in nature, however, and they require crystalline materials.…”