Structure and Humidity-sensitive Properties of TiO_2-doped α-Fe_2O_3-K_2O Nanometer-sized Ceramics

TiO2 waJs 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 chaxacteristic 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.