Sintering rates for pristine and doped titanium dioxide determined using a tandem differential mobility analyzer system

Sintering rates of pristine and V-doped TiO₂ were obtained using a tandem DMA system. A range of experiments were conducted to first map out the variation of mobility size of a monodisperse (by mobility) agglomerate with time at three fixed temperatures. Using relationships of the surface area to the mobility size, the sintering equation was solved to determine the activation energy and pre-exponential factor. The value of the activation energy was 236 (±46) kJ/mol for pristine TiO₂ and 363 (±1) kJ/mol for V-doped TiO₂. The corresponding pre-exponential factors were 7.22 × 10¹⁹ and 2.22 × 10¹² s/m⁴K, respectively. These values were then used to predict changes in mobility diameter at different temperatures, and good agreement was obtained with measurements. Possible reasons for faster sintering rates of V-TiO₂ relative to pristine TiO₂ were conjectured.