Kinetics and mechanism of anatase-to-rutile phase transformation in the presence of borosilicate glass

摘要

The effects of borosilicate glass (BSG) on the kinetics and mechanism of anatase- to-rutile phase transformation have been investigated. The displacive anatase-to-rutile phase transformation kinetics of TiO_2 were greatly enhanced in the presence of BSG. The transformation kinetics followed the Avrami equation, and the results showed an apparent activation energy of 260-370 kJ/mol, which was close to the bond strength of Ti-O, suggesting a reaction-controlling mechanism. The values of the Avrami exponent were in the range of 1.4-2.3, which could be interpreted as two-dimensional reaction-controlled growth at zero nucleation rate. The rutile particles obtained by the phase transformation were always much larger than the starting anatase powders, which was explained by a mechanism of phase-transformation-induced particle coalescence.