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通过高分辨透射电镜法,差示扫描量热法和x射线衍射法分析了二氧化钛凝胶向锐钛矿转变的相变过程。结果发现,三种方法测试的相变行为并不完全一致。透射电镜分析结果表明,在100℃干燥24 h的非晶态凝胶中存在少量的结晶不完全的锐钛矿相;然而x射线衍射法并未检测出晶体。随着烧结温度的升高,锐钛矿的晶格常数c逐渐降低,当温度达到300℃以后接近标准值(如,JCPDS卡片号84-1285)。而晶格常数a则保持了相对稳定并且透射电镜法和x射线衍射法计算出的结果基本一致。另外,透射电镜法分析的锐钛矿的晶粒度大于x射线衍射法检测出的晶粒度。
The phase transformation of titanate gel to anatase was analyzed by high resolution transmission electron microscopy, differential scanning calorimetry and x-ray diffraction. The results show that the three methods tested the phase transition behavior is not exactly the same. Transmission electron microscopy analysis showed that there was a small amount of incompletely crystalline anatase phase in the amorphous gel dried at 100 ℃ for 24 h; however, the crystal was not detected by X-ray diffraction. As the sintering temperature increases, the lattice constant c of anatase decreases gradually, approaching the standard value (for example, JCPDS card number 84-1285) after the temperature reaches 300 ° C. While the lattice constant a is kept relatively stable and the results calculated by the transmission electron microscopy and the x-ray diffraction are basically the same. In addition, the anatase size analyzed by transmission electron microscopy is greater than the grain size detected by x-ray diffraction.