| Texto completo | |
| Autor(es): |
Correa, Leonardo M.
;
Moreira, Murilo
;
Rodrigues, Varlei
;
Ugarte, Daniel
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION; v. 42, n. 9, p. 12-pg., 2025-05-13. |
| Resumo | |
Atomic arrangement in decahedral (Dh) nanoparticles remains an open and contentious question. The well-accepted Bagley model predicts a homogeneous deformation of face-centered cubic (FCC) crystal into a body-centered orthorhombic (BCO) one, including a 5% expansion along the 5-fold axis. This BCO model is questioned by experimental evidence of localized deformations or observation of Dh wires with body-centered tetragonal lattice (BCT). Transmission electron microscopy (TEM) images may be used to detect strain fields, but 2D projection nature of images inhibits the complete assessment of 3D distortion fields. Here, the average unit-cell symmetry and size of few-nm-wide surfactant-free noble metal (AuAg) nanoparticles are studied using a structural refinement based on Pair Distribution Function (PDF) derived from Precession Electron Diffraction (PED). The results indicate that the Bagley BCO model is clearly unable to provide a good description, and that the occurrence of a tetragonal symmetry cannot be excluded within experimental errors. Structural refinement has followed rigorous uncertainty estimation and solution search procedures, considering physical constraints and a minimal number of variables. The PDF approach shows high potential to obtain information of the average unit cell in nanocrystals using low electron total irradiation dose (approximate to 10 e(-) /& Aring;(-2)). (AU) | |
| Processo FAPESP: | 14/01045-0 - Estudo por técnicas avançadas de microscopia eletrônica de agregados metálicos e materiais nanocompósitos utilizados em aplicações fotovoltaicas |
| Beneficiário: | Daniel Mario Ugarte |
| Modalidade de apoio: | Bolsas no Exterior - Pesquisa |
| Processo FAPESP: | 07/01722-9 - Desenvolvimento de uma fonte de nano-agregados metálicos selecionados em massa |
| Beneficiário: | Varlei Rodrigues |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 20/15497-1 - Fabricação e caracterização de filmes finos poliméricos com nanopartículas metálicas embebidas e sua aplicação em sensores |
| Beneficiário: | Varlei Rodrigues |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |