Decomposition behaviours of dopant-free and doped solid solutions in the TiO₂-SnO₂ system

Abstract

Decomposition behaviours, including phase separation by the spinodal mechanism, were investigated for selected compositions ofx = 0.7, 0.5 and 0.3 in Ti _x Sn_1−x O₂ alloy. Inside the coherent spinodal, an equimolar alloy was found to decompose most rapidly at 1100° C and the decomposition rate decreased as the annealing temperature increased. The difference in the rate of decomposition outside the spinodal betweenx = 0.7 andx = 0.3 alloys suggested that the ionic mobility of diffusing tin was much slower than that of titanium in the alloy system. The effect of some dopants on the decomposition rate was also examined. Doping with tungsten or antimony atoms strongly suppressed the phase separation both inside and outside the spinodal, especially resulting in a prolonged stabilization ofx = 0.7 alloy. The role of the dopants in affecting the decomposition rate is discussed in relation to selective substitution of the doping atoms in the tin or titanium sublattice.