Modification of spherical SiO2 particles via electrolyte for high zeta potential and self-assembly of SiO2 photonic crystal

• Autor(a) principal: Liu,Li-ying
• Data de Publicação: 2009
• Outros Autores: Wang,Xiu-feng, Cheng,Bing, Zhang,Chun-xiang
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532009000100009
• topic: photonic crystal; SiO2 particles; modification; electrolyte

Spherical SiO2 particles were prepared by a novel co-precipitation process improved by electrolyte NaCl for charging and further self-assembled into photonic crystal by vertical deposition method. The obtained composites and their structures were characterized by scanning electron microscope (SEM) with X-Ray energy dispersive spectroscopy (EDS), Zetasizer, and UV-Vis spectrophotometer. SEM images indicated that the SiO2 particles were spherical and the average diameter of modified SiO2 particles was about 380 nm, larger than that of the unmodified ones (315 nm). Moreover, when the amount of NaCl was excessive (10 mg), bimodal diameter distribution SiO2 particles were obtained and the diameters were about 110 nm and 420 nm respectively. Compared with the unmodified SiO2 particles, EDS spectra of the modified ones showed an obvious characteristic-peak of Na element which proved that the Na element existed in the SiO2 particle. The results of Zetasizer revealed that the average Zeta potential of the modified SiO2 particles in ethanol was -56.6 mV, which was much higher than that of the unmodified ones (-48.7 mV). So the photonic crystal that self-assembled by the modified SiO2 particles possessed face-centred cubic structure with fewer defects. In addition, UV-Vis spectrophotometer showed that photonic band gap of the modified SiO2 photonic crystal had a red-shift and the absorption peak became narrower and higher.