Multiple Growth Stages and Their Kinetic Models of Anatase Nanoparticles under Hydrothermal Conditions

Hydrothermal growth, structural analyses, and growth kinetics of anatase nanoparticles have been paid extensive attention. The growth was generally related to either Ostwald ripening (OR) or orientation attachment (OA). However, very few works about hydrothermal crystallization of anatase nanoparticles have covered both OR and OA. In this work, we present a unique three-stage hydrothermal growth of anatase nanoparticles in succinic acid: OA, shrinkage, and OR. The growth procedures are experimentally monitored by powder X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) in detail. The calculated crystalline sizes by the Scherrer equation unambiguously suggest the three-stage growth mechanism. This is further evidenced by vivid high resolution TEM (HRTEM) images and their related fast Fourier transform (FFT) patterns. For each growth stage, a kinetic model by using mathematic equations is proposed and addressed in detail.