Activation Volumes for Solid-Solid Transformations in Nanocrystals
Keren Jacobs,
David Zaziski,
Erik C. Scher,
Amy B. Herhold,*
A. Paul
Alivisatos
The transition between four- and six-coordinate structures in CdSe
nanocrystals displays simple transition kinetics as compared with the
extended solid, and we determined activation volumes from the pressure
dependence of the relaxation times. Our measurements indicate that the
transformation takes place by a nucleation mechanism and place strong
constraints on the type of microscopic motions that lead to the
transformation. The type of analysis presented here is difficult for
extended solids, which transform by complicated kinetics and involve
ill-defined domain volumes. Solids patterned on the nanoscale may prove
to be powerful models for the general study of structural transitions
in small systems, as well as in extended solids.
Department of Chemistry, University of California, Berkeley,
Berkeley, CA 94720, USA, and Materials Science Division, Lawrence
Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
*
Present address: Corporate Strategic Research, Exxon Mobil
Research and Engineering Company, Route 22 East, Annandale, NJ 08801, USA.
To whom correspondence should be addressed. E-mail:
alivis{at}uclink4.berkeley.edu
