Europhys. Lett.
Volume 69, Number 3, February 2005
Page(s) 385 - 389
Section Condensed matter: structure, mechanical and thermal properties
Published online 24 December 2004
Europhys. Lett., 69 (3), pp. 385-389 (2005)
DOI: 10.1209/epl/i2004-10354-7

Lattice dynamics of the lanthanides: Samarium at high pressure

H. Olijnyk and A. P. Jephcoat

Department of Earth Sciences, University of Oxford - Oxford OX1 3PR, UK

received 4 August 2004; accepted in final form 19 November 2004
published online 24 December 2004

Sm was studied by Raman spectroscopy at pressures up to 20 $\un{GPa}$. The Raman-active phonon modes, both of the Sm-type phase and the dhcp phase, show a frequency decrease as pressure increases. There is evidence that the entire structural sequence $\tx{hcp}\rightarrow\tx{Sm}$- $\tx{type}\rightarrow\tx{dhcp}\rightarrow
\tx{fcc}$ under pressure for the individual regular lanthanides is associated with softening of certain acoustic and optical-phonon modes as well as elastic anomalies. Comparison is made to corresponding transitions between close-packed lattices in other metals and possible relations to the lanthanide's electronic structure are addressed.

62.50.+p - High-pressure and shock wave effects in solids and liquids.
64.70.Kb - Solid-solid transitions.
63.20.-e - Phonons in crystal lattices.

© EDP Sciences 2005