Non-leachable highly luminescent ordered mesoporous SiO₂spherical particles

Abstract

Ordered mesoporous highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS) and either cetyltrimethylammonium bromide (CTAB) or the block copolymer Pluronic F-68 as structure-directing agents. Rhodamine B (RhB)-containing samples were prepared by using a simple wet impregnation method followed by the growing of a second silica shell in order to prevent leaching of the dye. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and photoluminescence (PL). Powders with polydisperse spherical grains were obtained displaying an ordered hexagonal array of mesochannels. Luminescence results reveal that RhB molecules have been successfully encapsulated into the channels of mesoporous particles as monomeric species and that a well-defined silica coating hindered dye leaching.

Effect of Dy3+ Amount on the Structural and Luminescence Properties of LaNbO4:Dy3+ Phosphor Obtained by One-Step Spray Pyrolysis Process

“…The Dy 3+ variation did not affect the particle morphology or the size distribution of the samples, which were consisted of polydisperse spherical particles with sizes between 16 nm and 1.5 µm of diameter. 44 All the samples presented a bimodal size distribution, where the first group presented diameters below 200 nm while the second one exhibited a mean size of around 600 nm. Figure 4 presents the size distributions and the correspondent SEM micrographs for the samples containing 5.0% of Dy 3+ ions.…”

“…Therefore, particles synthesized by the SP process can be obtained on a laboratory or on an industrial scale. [22][23][24][25] Among the various materials doped with lanthanide ions (Ln 3+ ) reported in the literature, nanomaterials doped with Dy 3+ are rarely mentioned as compared to the other Ln 3+ . Dy 3+ easily reaches the maximum concentration (quenching), and the nature of the host matrix strongly influences emission from this ion.…”

Fluorescent hybrid organic–inorganic particles: influence of physical encapsulation versus covalent attachment on leaching and UV stability

“…Leaching can be reduced, with the added benefit of photophysical enhancement of fluorescence, with the addition of a silica shell around the dye-containing core (Scheme 1). 32) Alternatively, hydrophobic dyes can be physically contained in hollow silica spheres prepared through oil-in-water emulsions where the silica forms at the surfactant-water interphase. 19) This method, used to encapsulate liquid organic dyes for sunscreens, 18) does permit release of dye due to mechanical rupture of some of shells during processing.…”

Estudo das propriedades luminescentes de íons Terras Raras em matrizes compósitas à base de alumina obtidas por pirólise de aerossol

“…Caso a camada sólida formada seja impermeável ao solvente, a pressão resultante do aquecimento no interior da partícula levará a fragmentação, Figura 13. Contudo, se a pressão dos gases envolvidos não for alta o suficiente e os gases forem aprisionados no interior da partícula sólidos ocos serão formados [GURAV et al, 1993;ROCHA, 2010].…”

“…Fonte: Imagem obtida da tese de L.A. Rocha [ROCHA, 2010], adaptada previamente do trabalho de Gurav [GURAV et al, 1993].…”