Artículos de revistas
Core-and-shell nature of Strober silica particles
Registro en:
Journal Of The Brazilian Chemical Society. Soc Brasileira Quimica, v. 12, n. 4, n. 519, n. 525, 2001.
0103-5053
WOS:000169920500013
10.1590/S0103-50532001000400013
Autor
Leite, CAP
de Souza, EF
Galembeck, F
Institución
Resumen
Two different samples of monodisperse Stober silica particles were examined in the analytical transmission electron microscope, using different imaging modes: bright-field, dark-field, energy-loss and elemental distribution maps. The particles (effective diameters = 141 and 36 nm) are formed by domains of variable O/Si ratio, which is consistent with a variable degree of hydration, and they coexist with particles with a high O/Si ratio measuring a few nanometers only, which appear dispersed in the picture background. Bright-field and energy-loss images of the larger particles show a core-and-shell morphology, and the shells have a higher amount of high-O/Si domains as well as contaminating carbon compounds. On the other hand, the smaller particles (effective diameter = 36 nm) are also formed by distinct domains, but their morphology is neither spherical or core-and-shell. The mechanisms for particle formation presented in the literature are discussed, considering the present findings. 12 4 519 525