Positronium study of porous structure of sol–gel prepared SiO₂: influence of pH

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• 作者：Misheva ; M. ; Djourelov ; N. ; Margaca ; F.M.A. ; Miranda Salvado ; I.M.
• 关键词：P305 ; P310 ; S160 ; P300 ; 78.70.Bj
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2001
• 出版时间：February, 2001
• 年：2001
• 卷：279
• 期：2-3
• 页码：196-203
• 全文大小：218 K

文摘

Positron annihilation lifetime and Doppler broadening of annihilation line techniques have been used to obtain information about the small-pore structure of SiO₂ prepared by the alkoxide method in different experimental conditions. Samples prepared in strong acidic environment (pH=2) contain only small pores with mean radius R5 Å, while those prepared at pH=6 and pH=9 contain pores of two sizes, R5 and R17–26 Å. The influence of pH, water/alkoxide molar ratio and temperature of heat-treatment of the samples on their pore structure has been studied.