Abstract: TiO₂ was doped in α-Fe₂O₃-K₂O composite system by a stearic acid-gel method. Phase composition，grain size，lattice distortion，specific
surface area，porosity and thermal stability of TiO₂-doped α-Fe₂O₃-K₂O nanometer-sized ceramics were investigated by X-ray diffraction，BET specific surface absorption and Archimede replacement water methods. The
results show that doping of a little amount of TiO₂ restrains the formation of KFe₁₁O₁₇ and β-K₂O，retards the growth of α-Fe₂O₃
grain，makes α-Fe₂O₃ lattice distortion，improves its thermal stability and keeps its phase structure of corundum as α-Fe₂O₃. Furthermore?，the relationship between TiO₂-doped amount and inner electrical resistance?，resistance-humidity characteristic and humidity hysteresis of the various
TiO₂-doped α-Fe₂O₃-K₂O system were also studied. It shows that K⁺ possibly more dispersedly exists in the amorphous surface shell layer of
α-Fe₂O₃ after doping TiO₂，and that is the main reason of humidity hysteresis being decreased.

Key words: doping, nanometer-sized material, α-hematite, humidity-sensitive