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Author Liu, S.; Rao, J.; Sui, X.; Cool, P.; Vansant, E.F.; Van Tendeloo, G.; Cheng, X.
Title Preparation of hollow silica spheres with different mesostructures Type A1 Journal article
Year 2008 Publication Journal of non-crystalline solids Abbreviated Journal J Non-Cryst Solids
Volume 354 Issue 10/11 Pages 826-830
Keywords A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Electron microscopy for materials research (EMAT)
Abstract Hollow silica spheres were quickly synthesized by an octylamine (OA) templating method using tetraethyl orthosilicate (TEOS) as the silica source. N2-sorption results indicate that the hollow spheres have high surface areas and pore volumes. XRD and TEM measurements reveal that the structure of the hollow spheres depends on the amount of TEOS used in the synthesis. When low amount of TEOS is added, the template-containing precursor spheres depict an XRD pattern with two peaks, which can be indexed to a lamellar phase. After the removal of the template, the obtained hollow spheres show no diffraction peaks in the XRD pattern, suggesting that the nanopores in the silica shells are disordered. If increasing the amount of TEOS, either the uncalcined or the calcined sample gives an XRD pattern with a single diffraction peak. The mesostructure of these hollow silica spheres is typically as HMS materials. TGA analyses suggest that the interaction between the silica species and surfactant is stronger in the latter case.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000253216700003 Publication Date 2007-09-17
Series Editor Series Title Abbreviated Series Title (up)
Series Volume Series Issue Edition
ISSN 0022-3093; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.124 Times cited 26 Open Access
Notes Gao Approved Most recent IF: 2.124; 2008 IF: 1.449
Call Number UA @ lucian @ c:irua:72018 Serial 2703
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Author Liu, S.; Wei, M.; Sui, X.; Cheng, X.; Cool, P.; Van Tendeloo, G.
Title A scanning electron microscopy study on hollow silica microspheres: defects and influences of the synthesis composition Type A1 Journal article
Year 2009 Publication Journal of sol-gel science and technology Abbreviated Journal J Sol-Gel Sci Techn
Volume 49 Issue 3 Pages 373-379
Keywords A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Electron microscopy for materials research (EMAT)
Abstract Defects on hollow silica spheres synthesized in a tetraethylorthosilicate-octylamine-HCl-H2O system were recorded by scanning microscope. Based on the results, influences of synthesis composition on the formation of these defects are discussed. It is evidenced that products prepared with different octylamine-to-tetraethylorthosilicate ratios may have surface depressions, cracks and non-hollow microspheres. However, by changing water and acid additions, these defects could be reduced or eliminated. Generally, samples synthesized with a large octylamine addition commonly exhibit surface depressions. A small octylamine or a large water addition benefits the formation of solid silica microspheres among the product. Acid, although is not indispensable for the formation of hollow spheres, helps to eliminate or reduce depressions on the hollow shells. It is explained that the added acid gives rise to a relative localized fast hydrolysis versus condensation, facilitating an easy mobility of hydrolyzed silica species, and consequently the shell surface is smoothened.
Address
Corporate Author Thesis
Publisher Kluwer Place of Publication Dordrecht Editor
Language Wos 000263260100015 Publication Date 2008-12-16
Series Editor Series Title Abbreviated Series Title (up)
Series Volume Series Issue Edition
ISSN 0928-0707;1573-4846; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.575 Times cited 1 Open Access
Notes Approved Most recent IF: 1.575; 2009 IF: 1.393
Call Number UA @ lucian @ c:irua:74962 Serial 2941
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