| Texto completo | |
| Autor(es): |
Santos, Mylena N.
;
Lourenco, Tuanan C.
;
Mocelim, Mauricio
;
Da Silva, Juarez L. F.
Número total de Autores: 4
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Physical Chemistry Chemical Physics; v. 26, n. 25, p. 16-pg., 2024-05-20. |
| Resumo | |
The combination of ceria (CeO2) with different metal oxides (MO2), e.g. Ce1-xMxO2, has been strategically used to enhance its intrinsic properties. Moreover, the controlled synthesis of mixed oxide nanoparticles (NPs) opens the opportunity to explore the size dependence and chemical composition of the physical-chemical properties. However, our atomic-level understanding of how the physical-chemical and thermodynamic characteristics change with particle size and composition remains far from satisfactory. Here, we used force-field molecular dynamics simulations to investigate the effects of composition (x) and size on the physical-chemical properties of Ce1-xZrxO2 NPs with diameter from 1 (32 cations) up to 3 nm (256 cations), where x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0. We found abrupt changes in potential energy versus temperature for NPs with more than 108 cations, indicating a structural phase transition from disordered to ordered structures, which was confirmed by the radial distribution function. We found a linear relationship between the phase transition temperature (T-pt) and the size and composition of the NPs: the increase in the molar fraction of Zr4+ and the reduction in particle size are related to lower T-pt temperature and less defined decays of potential energy versus temperature. NPs larger than 56 cations show a radial distribution function with several peaks, which is related to the order of cations and anions in these structures. These peaks gradually disappear as the size decreases and the fraction of Zr4+ increases. Similar trends were observed with X-ray diffraction analysis; for example, fluorite-like motifs occur even with 56 cations in the case of ceria, but only for NPs with 108 cations for zirconia. Common neighbor analysis confirmed that NPs with well-defined values of the temperature T-pt have face-centered cubic (fcc)-like domains in the core region. The number of ordered fcc cations increases with increasing NP size and decreasing Zr4+ concentration. Finally, we observed that ceria nucleate first during simulated annealing and occupy highly coordinated sites within the core, while Zr4+ prefers the lowest coordinated sites on the surface. (AU) | |
| Processo FAPESP: | 19/23681-0 - De métodos ab initio até o contínuo para a busca de materiais para baterias de sódio-íon |
| Beneficiário: | Tuanan da Costa Lourenço |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 18/21401-7 - EMU concedido no processo 2017/11631-2: cluster computacional de alto desempenho - ENIAC |
| Beneficiário: | Juarez Lopes Ferreira da Silva |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Equipamentos Multiusuários |
| Processo FAPESP: | 22/05652-5 - Campos de força polarizáveis para a Investigação de materiais de bateria de sódio-íon |
| Beneficiário: | Tuanan da Costa Lourenço |
| Modalidade de apoio: | Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado |
| Processo FAPESP: | 20/10532-3 - Estudo das propriedades estruturais e energéticas de nanoligas formadas por CeO2-ZrO2 via cálculos de dinâmica molecular |
| Beneficiário: | Mylena Novaes Santos |
| Modalidade de apoio: | Bolsas no Brasil - Iniciação Científica |
| Processo FAPESP: | 17/11631-2 - CINE: desenvolvimento computacional de materiais utilizando simulações atomísticas, meso-escala, multi-física e inteligência artificial para aplicações energéticas |
| Beneficiário: | Juarez Lopes Ferreira da Silva |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia |