Multiband light emission and nanoscale chemical analyses of carbonized fumed silica
Resumen: Fumed silica with a specific area of 295 m(2)/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 degrees C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible emission in annealed samples originated from inorganic pyrolytic carbon precipitates dispersed in the silica host matrix. Two types of emission bands were identified as a function of the annealing temperature: one is in the near UV and the other is in the visible range. Based on the emission/excitation analysis of these two bands, as well as on correlations with the synthesis conditions, a structural-energy concept of light-emitting centers has been proposed. According to this model, the light-emitting centers are associated with carbon clusters that can be bonded or adsorbed on the silica surface. This has been validated by a detailed (S)TEM-electron energy-loss spectroscopy study, confirming the inhomogeneous distribution of nanoscale carbon precipitates at the surface of the silica nanoparticles. These carbon precipitates are mostly amorphous although they possess some degree of graphitization and local order. Finally, the fraction of sp(2) carbon in these nanoclusters has been estimated to be close to 80%. Published by AIP Publishing.
Idioma: Inglés
DOI: 10.1063/1.5042671
Año: 2018
Publicado en: Journal of Applied Physics 124, 10 (2018), 105108 [12 pp]
ISSN: 0021-8979

Factor impacto JCR: 2.328 (2018)
Categ. JCR: PHYSICS, APPLIED rank: 59 / 148 = 0.399 (2018) - Q2 - T2
Factor impacto SCIMAGO: 0.746 - Physics and Astronomy (miscellaneous) (Q2)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E26
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2016-79776-P
Tipo y forma: Artículo (Versión definitiva)
Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)

Derechos Reservados Derechos reservados por el editor de la revista

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