Controllable synthesis of zirconia nano-powders using vapor-phase hydrolysis and theoretical analysis

Abstract

The feasibility of controllable synthesis of nano-crystalline ZrO₂ powders using vapor-phase hydrolysis was studied. XRD, SEM, TEM, BET and TG-DTA methods were used to investigate the phase composition, particle size, and agglomeration. The formation process of the nano-particles was also analyzed with the classic Smoluchowski theory, the coupled cluster theory [CCSD(T)]/aT and/or Møller–Plesset perturbation theory (MP2)/aT. The results show that the morphology and size of the ZrO₂ nano-particles were very much dependent on the ratio of ZrCl₄ : H₂O, which played an important part in determining the characteristics of the ZrO₂ nano-particles. By increasing the concentration of water to decrease their collision rate and prevent nano-particle agglomeration, the size distribution of the nano-particle product would be decreased and a more monodisperse nano-particle product would be collected. In particular, the best characteristics were obtained using a precursor ratio of 1 : 40 (ZrCl₄ : H₂O). The nano-powders had a small particle size (15 nm), a high degree of crystallinity and very weak agglomeration, in a continuous instead of batch operation. This route is free of powder drying and calcination processes that are essential for wet chemical preparation, contributing to less agglomeration.