Synthesis and Thermal Stability of HfO_2 Nanoparticles

摘要

A simple method is reported for the synthesis of monodispersed HfO_2 nanoparticles by the ammonia catalyzed hydrolysis and condensation of hafnium (IV) tert-butoxide in the presence of surfactants at room temperature. Transmission electron microscopy shows faceted nanoparticles with an average diameter of 3-4 nm. As-synthesized nanoparticles are amorphous in nature and crystallize upon moderate heat treatment. The HfO_2 nanoparticles have a narrow size distribution, large specific surface area and good thermal stability. Specific surface area was about 239 m~2/g on as-prepared nanoparticle samples while those annealed at 500 °C have specific surface area of 221 m~2/g indicating that there was no significant increase in particle size. This result was further confirmed by TEM images of nanoparticles annealed at 300 °C and 500 °C. X-ray diffraction studies of the crystallized nanoparticles revealed that HfO_2 nanoparticles were monoclinic in structure. The synthetic procedure used in this work can be readily modified for large scale production of monodispersed HfO_2 nanoparticles.