Raman spectroscopy is used to study phase transition and phonon confinement effect for titanium dioxide nanocrystals. A chemical solution process was developed to prepare TiO2 nanocrystals with average grain sizes of 6.8 - 27 nm. As the grain size decreases, the lowest - frequency Eg mode at 152cm-1 shows blueshift and broadening. The frequency shift and line width broadening were theoretically studied at different grain sizes of 6.8, 10.3 and 27.9nm under phonon confinement model, showing good agreement with experimental results. Non -stoichiometry effect was recorded by redshift of the 422 cm-1Eg mode, libration mode of the oxygen atoms along the c - axis. The rutile - anatase transformation for TiO2 nanocrystal is in range of 650 - 690 ℃, lower than that from the bulk(1000℃), showing the size - effect for the transition.%拉曼光谱用于研究二氧化钛材料的相变和声子限制效应.化学溶液方法制备了TiO2纳米晶材料.其平均粒度为6.8-27.9 nm.最低频率152cm-1Eg模随粒度减小出现蓝移和加宽.在声子限制模型下,理论上对不同粒度的TiO2纳米晶(6.8,10.3和27.9 nm)的频移和线宽进行计算,结果与实验吻合得很好.研究了TiO2纳米晶锐钛矿-金红石相变,其相变温度为650-690℃,比体块TiO2的相变温度1000℃低,表明了相变的尺寸效应.
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