[Zurück]

V. Paul-Boncour, A. Lindbaum, M. Latroche, S. Heathman:
"Homogeneity range and order-disorder transitions in R_1-xNi₂ Laves phase compounds";
Intermetallics, 14 (2006), S. 483 - 490.

Homogeneity range and order-disorder transitions in R_1-xNi₂ Laves phase compounds

V. Paul-Boncour a, A. Lindbaum b, M. Latroche a and S. Heathman c

a Laboratoire de Chimie Métallurgique des Terres Rares, C.N.R.S, ISCSA, 2-8 rue Henri Dunant, F-94320 Thiais, France
b Institute for Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/131, A-1040 Vienna, Austria
c European Commission, JRC, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany

Received 28 April 2005; revised 4 July 2005; accepted 15 August 2005. Available online 16 November 2005.

Abstract

The homogeneity range of R_1-xNi₂ Laves phases (R=Ce, Gd, Tb) has been studied by X-ray diffraction, microprobe analysis and density measurements. In these compounds, the number of R vacancies varies as a function of the atomic number of the rare earth metal and the nominal composition. For R=Tb the number of vacancies varies by 0<=x<=0.5, with a change of the structure from a pure C15 structure to a 2a superstructure accompanied by a cell volume decrease. The order-disorder transition of the rare-earth vacancies has been studied under applied pressure for La₇Ni₁₆ and as a function of temperature for all the R_1-xNi₂ compounds. The evolution of the transition pressure and temperature, which reflects the binding energy of the vacancies in the lattice, depends not only on the radius of the R atoms but also on their masses.

Keywords: A. Laves phases; D. Defects: constitutional vacancies; F. Diffraction; F. Calorimetry; F. Metallographic techniques

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC06588029

http://dx.doi.org/10.1016/j.intermet.2005.08.003