Structural properties of core and surface of silica nanoparticles investigated by Raman spectroscopy

Abstract

We studied the experimental Raman spectra of various commercial silica nanoparticles of average diameter from 7 to 40 nm and specific surface from 50 to 380 m^2/g. We found that the peculiarities of the particles Raman spectra systematically depend on their specific surface. In detail, the peak position of the R band at about 440 cm ^-1 shifts towards high wavenumbers following an almost linear dependence on the specific surface. Similarly, the amplitudes of the D1 and D2 bands,\ud at about 495 and 605 cm ^-1, respectively, increase linearly with the same quantity. Our results are interpreted in the frame of the shell model for the nanoparticles clarifying that the network of the core of the nanoparticles is comparable to the bulk silica materials, whereas the surface shell has a ring statistic shifted to the low member rings and features an higher density

A microbial protein-assisted silica ball comprising of silica-nanoparticles with plausible optical properties for multiple applications

“…Subsequently, Raman studies of SiO 2 -NPs have been established the surfacerelated optical properties as well. However, Raman peak amplitude of SiO 2 -NPs scientifically depends on the specific surface areas as similar to previous literature [23].…”

Silica nanoparticle core structure examined by the E′Siγ center 29Si strong hyperfine interaction

“…We produced tablets from the nanoparticle powders by applying a pressure of about 0.3 GPa using a mechanical press. As reported in previous investigations, such procedure does not modify the structure of the nanoparticles [11].…”

“…Different studies proposed that the silica nanoparticles can be described by a core-shell model in which the particle is divided in an inner part (core) and in a surface shell [7][8][9][10][11][12]. Regarding this latter, some studies have proposed that it has a thickness of about 1 nm, independently from the particle size [8,10], and a peculiar structure with a density higher than the one of the bulk silica [9,11].…”

“…Regarding this latter, some studies have proposed that it has a thickness of about 1 nm, independently from the particle size [8,10], and a peculiar structure with a density higher than the one of the bulk silica [9,11]. In addition, it has been suggested, but not definitively proven until now, that the nanoparticle core structure is independent from the particle size [8][9][10][11], and shows some structural differences with respect to the bulk [7,11]. To deeply understand the core structure of different nanoparticles and to better compare its amorphous network with the bulk, a relevant role can be covered by the study of the 29 Si strong hyperfine interaction related to the E′Si γ point defect [2].…”

“…Different studies proposed that the silica nanoparticles can be described by a core-shell model in which the particle is divided in an inner part (core) and in a surface shell [7][8][9][10][11][12]. Regarding this latter, some studies have proposed that it has a thickness of about 1 nm, independently from the particle size [8,10], and a peculiar structure with a density higher than the one of the bulk silica [9,11]. In addition, it has been suggested, but not definitively proven until now, that the nanoparticle core structure is independent from the particle size [8][9][10][11], and shows some structural differences with respect to the bulk [7,11].…”