Effects of aging on the phase transformation and sintering properties of TiO2 gels

In this study, the effects of aging on the crystalline phases, crystallite sizes, and sintering properties of TiO2 gels were investigated by using thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffractometer (XRD), dilatometer and scanning electron microscopy (SEM). With increasing aging time, the hydroxyl ions existing in the anatase lattice decreased, and so the oxygen vacancy concentration produced after calcination decreased. Consequently, increasing aging time during sintering lowered the crystallite growth rate of anatase. The densification of the TiO2 powders was dependent upon the aging time which shifted the anatase→rutile (a→r-TiO2) phase transformation to higher temperature and lowered the crystallite growth rate during sintering.