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用DTA（差热分析）、TG（热重分析）和X射线衍射分析，研究了Fe2O3和TiO2纳米晶粒的结构相变．结果表明，对于Fe2O3纳米晶粒，只要没有发生γ→α转变，纳米晶粒就保持其原来的尺寸不变，而一旦发生了相变，晶粒的尺寸就会迅速长大．同样，对TiO2纳米晶粒，在从锐钛矿相→板钛矿相→金红石相的相变过程中，在相变发生以前，不管温度多高，纳米晶粒都保持其原来的尺寸不变，只要发生了相变，晶粒的尺寸就会迅速长大．对于纳米晶粒，依赖于晶粒尺寸的结构相变和依赖于结构相交的晶粒生长过程都是存在的．这是纳米晶的一种新的尺寸效应．
The structural phase transitions of Fe2O3 and TiO2 nanocrystals were investigated by DTA (Differential Thermal Analysis), TG (Thermogravimetric Analysis) and X-ray Diffraction (XRD). The results show that for the Fe2O3 nanocrystalline grains, as long as no γ → α transformation occurs, the nanocrystalline grains remain unchanged in their original size, and the grain size grows rapidly once the phase transformation occurs. Similarly, for the TiO2 nanocrystals, during the phase transition from anatase phase to brook phase to rutile phase, the nanocrystal grains remain unchanged in size until the phase change occurs regardless of the temperature As long as a phase change occurs, the grain size grows rapidly. For nanocrystalline grains, both structural phase changes that depend on grain size and grain growth that depend on structural intersections exist. This is a new size effect of nanocrystals.