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In-Situ Synchrotron Radiation Study of Formation and Growth of Crystalline CexZr1-xO2 Nanoparticles Synthesized in Supercritical Water

Författare:
  • Christoffer Tyrsted
  • Jacob Becker
  • Peter Hald
  • Martin Bremholm
  • Jan Skov Pedersen
  • Jacques Chevallier
  • Yngve Cerenius
  • Steen B. Iversen
  • Bo B. Iversen
Publiceringsår: 2010
Språk: Engelska
Sidor: 1814-1820
Publikation/Tidskrift/Serie: Chemistry of Materials
Volym: 22
Nummer: 5
Dokumenttyp: Artikel
Förlag: Amer Chemical Soc

Sammanfattning

In situ synchrotron powder X-ray diffraction (PXRD) measurements have been conducted to follow the nucleation and growth of crystalline CexZr1-xO2 nanoparticles synthesized in supercritical water with a full substitution variation (x = 0, 0.2, 0.5, 0.8, and 1.0). Direction-dependent growth curves are determined and described using reaction kinetic models. A disctinct change in growth kinetics is observed with increasing cerium content. For x = 0.8 and 1.0 (high cerium content), the growth in initially limited by the surface reaction kinetics, however, at a size of similar to 6 nm, the growth changes and becomes limited by the diffusion of monomers toward the surface. For x = 0 and 0.2, the opposite behavior is observed with the growth initially being limited by diffusion (up to similar to 3.5 nm) and later by the surface reaction kinetics. Thus, although a continuous solid solution can be obtained for the ceria-zirconia system, the growth of ceria and zirconia nanoparticles is fundamentally different under supercritical flow reactor. The resulting samples were analyzed using PXRD, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). The nanoparticles with x = 0, 0.2, and 0.5 have very low polydispersities. The sizes range from 4 nm to 7 nm, and the particles exhibit a reversibly pH-dependent agglomeration.

Disputation

Nyckelord

  • Physics and Astronomy

Övriga

Published
Yes
  • ISSN: 0897-4756

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