33. Shape-Preserving Chemical Conversion of Self-Assembled 3-D Bioclastic Micro/Nanostructures Via Low-Temperature Displacement Reactions
- Dongming Zhu and
- Kevin Plucknett
Published Online: 26 MAR 2008
Copyright © 2005 The American Ceramics Society
Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3
How to Cite
Allan, S. M., Weatherspoon, M. R., Graham, P. D., Cai, Y., Haluska, M. S., Snyder, R. L. and Sandhage, K. H. (2005) Shape-Preserving Chemical Conversion of Self-Assembled 3-D Bioclastic Micro/Nanostructures Via Low-Temperature Displacement Reactions, in Advances in Ceramic Coatings and Ceramic-Metal Systems: Ceramic Engineering and Science Proceedings, Volume 26, Number 3 (eds D. Zhu and K. Plucknett), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470291238.ch33
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 2005
Print ISBN: 9781574982336
Online ISBN: 9780470291238
An astounding variety of self-assembled, rigid (bioclastic) micro/nanostructures are generated by micro-organisms known as diatoms (single-celled algae). Each diatom species assembles an intricate silica nanoparticle-based microshell (frustule) with a particular three-dimensional (3-D) shape and with specific patterns of nanoscale features (pores, channels, ridges, protuberances, etc.). Sustained reproduction of a single diatom can yield enormous numbers of intricate frustules with identical 3-D shapes and fine features. The massive parallelism and genetic precision of such 3-D nanoparticle self-assembly are highly attractive for device applications. However, in order to expand the use of such micro/nanostructures into a broad range of applications, processes need to be developed to change the silica-based chemistry of diatom frustules into other compositions, so as to achieve a wider variety of properties.
Displacement reactions can be used to convert SiO2-based diatom frustules into other oxides while preserving the 3-D morphology of the starting frustule. In this paper, an oxidation-reduction reaction between Mg gas and SiO2 frustules has been used to convert the frustules into MgO-bearing replicas. The influence of processing parameters (reaction temperatures, times, and reactant ratios) on the nanostructural evolution, and on the final product phases (particularly the secondary Si-bearing phases), has been examined. Nanocrystalline MgO-bearing replicas of diatom frustules have been synthesized at temperatures as low as 650°C within a few hours.