摘要：采用超临界水热合成法制备TiO₂纳米粉体, 研究反应条件包括温度、压力、反应时间对纳米粉体颗粒的粒径大小、形貌及结晶度的影响。结果表明, 随着温度从亚临界升高到超临界, TiO₂颗粒粒径急剧减小, 且结晶度增大, 最终合成10 nm左右结晶度良好的椭球形颗粒。颗粒在26~30 MPa的压力范围内, 结晶度随着反应压力的增大而增大, 但粉体粒径大小差别不大。在1 min的反应时间内即检测出了TiO₂物相, 而在5 min后生成了结晶良好的椭球形晶体, 随着反应时间的增加, 棒状的颗粒逐渐增多, 这是由于发生了溶解-结晶机理。

关键词：超临界水热合成；纳米颗粒；形貌；粒径；结晶度

Abstract：TiO₂ nano-powders were synthesized by supercritical hydrothermal synthesis (SCHS) technology. The effects of reaction conditions including temperature, pressure, reaction time on the particle size, morphology and crystallinity were studied. The present results indicated that the particle size of synthesized TiO₂ decreases dramatically but the crystallinity of particles increases with the temperature increasing from subcritical state to supercritical state. Finally ellipsoidal nanoparticles of 10 nm are obtained. In pressure range of 26~30MPa, higher pressure is found to be in favor of improving the crystallinity degree of TiO₂ nano-particles, but the particle size changes very little. The titania phase is detected in 1 min reaction time, well-crystallized ellipsoid crystals are obtained when reaction time is 5 min. With the increase of reaction time, the number of rod-shaped particles increases gradually. The particle growth seems to be driven by dissolving-crystallization mechanism.

Keywords: SCHS；nano- particles；morphology；particle size；crystallinity