| Texto completo | |
| Autor(es): Mostrar menos - |
Santos, Suzilene V.
;
Costa, Cleidilane S.
;
Paraguassu, Waldeci
;
Silva, Crystian W. C.
;
Otubo, Larissa
;
Souza, Katiusse S.
;
Correa, Bruno S.
;
Miranda-Filho, Arnaldo A.
;
Ferreira, Wanderson L.
;
Carbonari, Artur W.
;
Cabrera-Pasca, Gabriel A.
Número total de Autores: 11
|
| Tipo de documento: | Artigo Científico |
| Fonte: | ACS OMEGA; v. 9, n. 42, p. 12-pg., 2024-10-10. |
| Resumo | |
The advancement of functional nanomaterials has become a major focus of recent research, driven by the exceptional properties these materials display compared to their macroscopic (bulk) counterparts. Cobalt oxide nanoparticles (CoO-NPs) stand out primarily for their catalytic and magnetic properties, which can enable a range of technological applications, such as advanced catalysts, drug delivery systems, implants, prosthetics, sensors. However, in addition to the dependence on factors such as size, morphology, and functionalization, the properties of CoO-NPs are significantly influenced by the crystal structure. Therefore, local investigation into the polymorphic structures of CoO at the nanometric scale may provide new insights into the local structural and magnetic characteristics of these systems. In this report, we address the synthesis and local characterization of cobalt oxide (CoO) nanoparticles in the rock-salt cubic fcc-CoO and Wurtzite hpc-CoO phases, obtained through thermal decomposition. We analyze the influence of oleylamine and oleic acid ligands on the structural and morphological control of these systems. The obtained nanoparticles were characterized using conventional techniques such as X-ray diffraction (XRD), transmission electron microscopy, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Local characterization was carried out by the perturbed angular correlation (PAC) nuclear technique using the radioactive tracer In-111(Cd-111). Measurements were conducted at 295 and 10 K to investigate possible magnetic phase transitions in these systems. XRD results confirmed the formation of fcc-CoO and hcp-CoO phases. The phase fcc was obtained with the pair of oleylamine and oleic acid ligands, while the phase hcp phase was synthesized using only oleylamine. Additionally, nanoparticles synthesized with oleylamine and oleic acid exhibited better morphological control compared to those produced with only oleylamine. Raman spectroscopy analyses suggest a phase transformation process resulting in Co3O4. PAC results for hyperfine interactions at the In-111(Cd-111) probe nucleus, indicate that the hcp-CoO phase shows smaller hyperfine magnetic interactions (B-hf = 1 T) compared to the fcc-CoO phase (B-hf = 17 T). This suggests the mechanism of superexchange interactions, which are strongly influenced by the Co-O-Co bond angle, which is 110 degrees for the hpc-CoO phase and 180 degrees for the fcc-CoO phase due to the geometries of the systems. (AU) | |
| Processo FAPESP: | 17/50332-0 - Capacitação científica, tecnológica e em infraestrutura em radiofármacos, radiações e empreendedorismo a serviço da saúde (PDIp) |
| Beneficiário: | Marcelo Linardi |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Modernização de Institutos Estaduais de Pesquisa |
| Processo FAPESP: | 14/14001-1 - Projeto e construção de um espectrômetro digital: um equipamento mais eficiente e moderno para investigação de materiais utilizando técnica PAC |
| Beneficiário: | Rajendra Narain Saxena |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |
| Processo FAPESP: | 14/50279-4 - Brasil Research Centre for Gas Innovation |
| Beneficiário: | Julio Romano Meneghini |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Centros de Pesquisa Aplicada |
| Processo FAPESP: | 20/15230-5 - Centro de Pesquisa e Inovação de Gases de Efeito Estufa - RCG2I |
| Beneficiário: | Julio Romano Meneghini |
| Modalidade de apoio: | Auxílio à Pesquisa - Programa Centros de Pesquisa Aplicada |