We follow the structural transformation in solid C70 from the high temperature hcp to a low temperature monoclinic phase using x-ray diffraction studies at controlled cooling-rates from 0.0033 to 0.42 K/min. Rapid cooling of the sample gives the signature of a two-step transformation which disappears when the system is transformaed quasi-statically. These experimental results can be rationalised using a simple mean field, Langevin dynamical theory using a free energy functional with minima corresponding to the parent and two competing product phases such that one of these product phases remains metastable throughout. The implication of our results on the existence of the intermediate phase in the sequence, hcp-dhcp-monoclinic, of structural transitions in solid C70 with the lowering of temperature is discussed.
@article{arxiv.cond-mat/9808232,
title = {Low temperature hcp to monoclinic structural transition in solid C$_{70}$ : Is there an intermediate phase?"},
author = {G. Ghosh and V. S. Sastry and C. S. Sundar and Surajit Sengupta and T. S. Radhakrishnan},
journal= {arXiv preprint arXiv:cond-mat/9808232},
year = {2009}
}
Comments
ReVTex (4 pages), 4 eps figures, accepted in Phys. Rev. B, minor changes in the title as well as in text