Phase transformation and crystal growth behaviors of La3+/Ce3+-doped TiO2-20 wt% SnO2 gels

The transformation behaviors of La3+/Ce3+-doped TiO2-SnO2 gels were studied by using differential thermal analysis and X-ray diffraction methods so as to improve the phase transformation and decrease the granularity of crystals. Experimental results show that, anatase, rutile and SnO2 nanocrystals can exist in the sintering products by varying La3+/Ce3+ contents and sintering temperatures. 0.8-1.1 wt% of La2O3 or CeO2 doping greatly depresses the growth of anatase and rutile crystals, obtaining nanosized crystals when sintered up to 600 degrees C for 2 h. With La3+/Ce3+-doping and increasing their contents, the transformations of gel to anatase and anatase to rutile, as well as the growth of anatase and rutile crystals can be depressed, while the transformation temperature of anatase to rutile receives much less affect. Moreover, the La3+-doping has stronger effects on them than Ce3+ doping, but has a weaker inhibiting effect on precipitation and growth of SnO2 crystals. (c) 2008 Elsevier B.V. All rights reserved.