Preparation of nanometric titanium hydrous oxide particles by vapour phasehydrolysis of titanium tetrabutoxide

Spherical titanium nanoparticles in the range of 60 to 500 nm have been obt ained by a vapour-phase hydrolysis procedure using titanium tetrabutaxide a s raw material. In this work, different parameters such as alkoxide tempera ture, water temperature, carrier gas flow rate, inlet pressure, vacuum and dilution of the raw material were tested. The most important parameters in order to obtain nanoparticles of low mean size were the flow rate, the alko xide temperature and the inlet pressure. When the temperature decreases the mean size decreases obtaining nanoparticles below 100 nm when the temperat ure is set up to 125 degrees C. On the other hand, as the flaw rate that pa ss through the alkoxide increases the particle size decreases. Same behavio ur is observed when the pressure inlet is increased. In all cases, these re sults are attributed to a minor concentration of the alkoxide (low amount o f alkoxide molecules) in the gas stream. The other parameters, vacuum, wate r temperature and dilution of the alkoxide did not show any important influ ence in the particle size as the other ones. Polydispersity (broad or narro w particle size distribution) has the same trend. The alkoxide temperature and carrier flow rate generate narrow distributions while the other paramet ers produces broad distributions. FT-IR analysis of these nanoparticles sho wed that for sizes below 100 nm the alkoxide is fully hydrolysed and as the particle size increases the nanoparticle has more alkoxide or alcohol reta ined inside. The heat treatment of these nanoparticles produces a decreasin g in the particle size and in all cases, the spherical shape is retained an d no blackening in the nanoparticles of higher size is observed. (C) 1999 K luwer Academic Publishers.