Europhys. Lett.
Volume 69, Number 3, February 2005
Page(s) 378 - 384
Section Condensed matter: structure, mechanical and thermal properties
Published online 05 January 2005
Europhys. Lett., 69 (3), pp. 378-384 (2005)
DOI: 10.1209/epl/i2004-10356-5

Atomic clusters and phase transitions in the metastable $\mth{\beta}$-Ta phase between $\mth{4.2}$ and $\mth{293}$ $\un{K}$

A. Arakcheeva and G. Chapuis

Ecole Polytechnique Fédérale de Lausanne, Institut de Physique de la Matière Complexe - BSP, 1015 Lausanne, Switzerland

received 19 July 2004; accepted in final form 19 November 2004
published online 5 January 2005

Atomic clusters were identified in the ground state of the non-equilibrium Ta phase (Frank-Kasper $\sigma$-structure type) at 15, 120 and 293 $\un{K}$. The evolution of the clusters with temperature leads to two phase transformations at 65 and 150 $\un{K}$ which are related to the electrical and magnetic properties. The magnetic phase transition at 65 $\un{K}$ is associated with the magnetic symmetry group transformation P4'2/mn'm ( <65 $\un{K}$) to $P\overline{4}'$ ( >65 $\un{K}$). It is shown that $\beta$-U is also a two-component composite containing similar clusters. The nature of the stabilisation of $\beta$-Ta at the cathode is discussed.

61.50.-f - Crystalline state.
61.66.Bi - Elemental solids.
64.60.My - Metastable phases.

© EDP Sciences 2005