ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Nano- and mesopores of bulk silica xerogels were studied by means of positron annihilation lifetime measurement as well as nitrogen physisorption. Effects of an alkaline catalyst concentration in the sol–gel process on the pore sizes and specific surface area were investigated. The pore size was estimated from the ortho-positronium lifetime. Remarkable structural changes were found around a relative alkaline concentration of 10−4 (a molar ratio of sodium hydroxide to tetramethyl ortho-silicate). Above this particular catalyst concentration, the nanopore radius decreased from 0.45 to 0.35 nm, whereas the mesopore radius increased from 1 to 8 nm. The positron annihilation lifetime technique was effective in the evaluation of the nano- and mesoscopic structural changes of silica xerogel.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.2003.tb03529.x
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