Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/41668

Title

Phase transformation as a function of particle size in nanocrystalline zirconia

Author(s)

Chraska, Tomas;  King, Alexander H.;  Berndt, Christopher C.;  Karthikeyan, Jeganathan

Abstract

Bulk zirconia undergoes a pressure-induced transformation from a (low pressure) monoclinic phase to a high pressure tetragonal phase, at around 3 GPa (above 900 K). We have studied the structures of zirconia nanoparticles formed by plasma-spraying an organo-metallic precursor. Inspection of the particles in the TEM reveals that they adopt one of two distinct crystal structures, depending upon their size. The smallest particles have the tetragonal structure, while larger ones are monoclinic. Interpolation of the data reveals a critical size above which the monoclinic structure is stable. Upon annealing, the zirconia particles coarsen and the small tetragonal particles transform to the monoclinic structure at about the critical size. Coarsening under these conditions produces irregular particle size distributions. We estimate that the surface-stress induced internal pressure in the tetragonal nanoparticles can be as high as 5 GPa and the corresponding surface stress is about 6 N/m.

Publication type

Conference paper

Source

Proceedings of Phase transformations and systems driven far from equilibrium, a Materials Research Society symposium, Boston, Massachusetts, United States, 01-05 December 1997 / Evan Ma, Michael Atzmon, Pascal Bellin and Rohit Trivedi (eds.), pp. 613-617

Publication year

1998

Keyword(s)

Annealing;  Crystal structure;  Interpolation;  Monoclinic structure;  Nanostructured materials;  Organometallics;  Particle size analysis;  Phase transitions;  Plasma spraying;  Pressure effects;  TEM;  Tetragonal structure;  Transmission electron microscopy;  Zirconia

Publisher

Materials Research Society

ISSN

0272-9172 (series ISSN)

ISBN

9781558993860, 155899386X

Peer reviewed