Abstract: By rheological experimental measurements of SnO₂ sol systems derived by the precursor
Tetrabutylorthostannate Sn(OBuⁿ)₄, it was reported that tear viscosity η, intrinsic viscosity [η] and pH values of the sol solution systems varied dynamically with time. Based on the rheologically dynamic observations, the growth character of SnO₂ sol
grains and its structural evolution rule were discussed, and proton H⁺ production phenomena associated with sol grain growth process were also explained. From
experimental investigations and theoretical discussion, the growth process of SnO_2 sol grains is controlled by a three-stage growth model,
and grain structure keeps invariant during the growth period before sol→gel transformation and sol solution acidity (pH)
influences profoundly the sol grain growth rates.

Key words: SnO₂ sol systems, rheological measurements, sol grain growth dynamics, grain growth model