Influence of La3+/Ce3+-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.