Premium
Synthesis of α ‐Willemite Nanoparticles by Post‐calcination of Flame‐made Zinc Oxide/Silica Composites
Author(s) -
Tani Takao,
Mädler Lutz,
Pratsinis Sotiris E.
Publication year - 2002
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/1521-4117(200211)19:5<354::aid-ppsc354>3.0.co;2-v
Subject(s) - calcination , materials science , chemical engineering , crystallization , nanoparticle , composite number , thermal stability , amorphous solid , pyrolysis , zinc , particle size , composite material , metallurgy , nanotechnology , catalysis , chemistry , crystallography , organic chemistry , engineering
Composite ZnO/SiO 2 nanoparticles were made by flame spray pyrolysis (FSP). Characteristics of the product powder and its crystallization behavior on post‐calcination were evaluated. Polyhedral aggregates of nano‐sized primary particles consisting of ZnO nano‐crystals 1–3 nm in size and amorphous SiO 2 were obtained by FSP. A short residence time in the flame can result in the co‐existence of the ZnO and SiO 2 clusters without substitution or reaction hindering each other's grain growth. There was almost no change in the XRD pattern by calcination at 600 °C for 2 h, suggesting a high thermal stability of the ZnO nano‐crystals in the composite particles. A pure α ‐willemite phase was obtained at 900 °C. At this calcination temperature, d C and d BET of the powder were 63 and 44 nm, respectively. The nano‐composite structure of the FSP‐made particles can suppress crystalline growth of ZnO during calcination to maintain a high reactivity of ZnO with SiO 2 , obtaining pure α ‐willemite with high specific surface area at low calcination temperatures.