Citric acid has been employed as a structural modifier for the first time t
o synthesize single silica nanotubes via a sol-gel process at room temperat
ure. XRD results reveal the amorphous nature of the silica framework. SEM a
nd TEM images show that the nanotubes were 0.5-20 mum in length, and 50-500
nm in width. TG-DTA and FTIR results indicate that the possible interactio
n between citric acid molecules and inorganic species should be very weak.
The structural direction of ammonium citrate crystals under appropriate syn
thetic conditions was argued to explain the formation of particular morphol