Influence of La/Ce-doping on phase transformation and crystal growth in TiO2-15 wt% ZnO gels

Titania based ceramic is a good candidate for environmental sensing materials. Ion doping is an effective method to improve the properties by modifying their microstructure and phase composition. By using differential thermal analysis and X-ray diffraction methods, the transformation behaviors of La³⁺/Ce³⁺-doped TiO₂-15  wt% ZnO gels were studied so as to modify the phase transformation and decrease the granularity of crystals. Experimental results show that, anatase, rutile and ZnTiO₃ nanocrystals can be tailored by varying La³⁺/Ce³⁺ contents and sintering temperatures. La³⁺/Ce³⁺ doping decreases the transformation temperature of gel to anatase and the forming temperature of ZnTiO₃ phase, enhances the transformation temperature of anatase to rutile and results in appearance of Zn₂Ti₃O₈ interphase. With the increases of La³⁺/Ce³⁺ contents, the transformation rates of ZnTiO₃, gel to anatase and anatase to rutile, as well as the granularity of the crystals are reduced. Ultimately, the action mechanism of La³⁺/Ce³⁺ doping was discussed.