6. 3-D Microparticles of BaTiO3 and Zn2SiO4 Via the Chemical (Sol-Gel, Acetate, or Hydrothermal) Conversion of Biological (Diatom) Templates

  1. William M. Mullins,
  2. Andrew Wereszczak and
  3. Egar Lara-Curzio
  1. Ye Cai,
  2. Michael R. Weatherspoon,
  3. Eric Ernst,
  4. Michael S. Haluska,
  5. Robert L. Snyder and
  6. Kenneth H. Sandhage

Published Online: 26 MAR 2008

DOI: 10.1002/9780470291375.ch6

Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8

Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8

How to Cite

Cai, Y., Weatherspoon, M. R., Ernst, E., Haluska, M. S., Snyder, R. L. and Sandhage, K. H. (2007) 3-D Microparticles of BaTiO3 and Zn2SiO4 Via the Chemical (Sol-Gel, Acetate, or Hydrothermal) Conversion of Biological (Diatom) Templates, in Synthesis and Processing of Nanostructured Materials: Ceramic Engineering and Science Proceedings, Volume 27, Issue 8 (eds W. M. Mullins, A. Wereszczak and E. Lara-Curzio), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291375.ch6

Author Information

  1. School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2007

ISBN Information

Print ISBN: 9780470080511

Online ISBN: 9780470291375

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Keywords:

  • multicomponent;
  • hydrothermal;
  • biologically;
  • microparticles;
  • morphologies

Summary

In this paper, the silica-based microshells of diatoms (planktonic micro-algae) have been used as biologically-replicable (i.e., scalable) 3-D templates for synthesizing functional multicomponent microparticles of controlled shape. Three shape-preserving chemical conversion approaches have been explored for the conversion of diatom microshells (frustules) into functional multicomponent oxides: sol-gel, acetate precursor, and hydrothermal routes. For the sol-gel approach, Si02 frustules were first converted by gas/solid reaction into MgO microparticles of similar shape. A conformal and continuous coating of BaTiO3 was then applied, via sol-gel processing, to the MgO microparticles. The underlying MgO templates were then selectively dissolved away to yield BaTiO3 microparticles that retained the overall shape of the starting frustules. In the acetate precursor route, a zinc acetate precursor solution was used to apply a coating of ZnO nanoparticles to Si02 frustules. The ZnO nanoparticles were then allowed to react at elevated temperature with the underlying SiO2 to form Zn2SiO4-bearing microparticles with the frustule shape. Finally, a metathetic gas/solid reaction was used to convert SiO2 frustules into TiO2. The titania microparticles were then converted into BaTiO3-based microparticles that retained the frustule shape via hydrothermal reaction with a barium hydroxide-bearing solution. These results demonstrate that several shape-preserving chemical approaches may be used to convert biologically-replicable 3-D nanostructured microtemplates into microparticles with functional multicomponent chemistries and with controlled morphologies.