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Accessible Unlicensed Requires Authentication Published by Oldenbourg Wissenschaftsverlag September 25, 2009

Metallic barrelane: crystal structure, physical properties and bonding analysis of La16Al13

Rainer Niewa, Martin Kirchner, Hui Zhang, Walter Schnelle and Yuri Grin

Abstract

Single crystals of the new intermetallic compound La16Al13 were obtained by thermal treatment of (La3O)Al in sealed Ta ampoules at 973 K, powder material for physical properties measurements from melt beads of appropriate composition at 773 K, well below the peritectic temperature of 978 K of the decomposition into LaAl and liquid. La16Al13 crystallizes hexagonal (space group P-62m, a = 918.3(2) pm, c = 1123.8(3) pm, Rgt(F) = 0.0293, Rall(F) = 0.0299, wR(F2) = 0.0621) with one formula unit per unit cell. The crystal structure can be described as built from layers of face-sharing Edshammar polyhedra (AlLa2La9/2)2 alternating with layers of barrelane-like Al11 cages linked by La. La16Al13 is a Pauli-paramagnet with metallic electrical resistivity. Electron localization function calculation reveals covalent interactions within the Al11 cages. The resulting large number of the ‘free’ charge carriers explains the metal-like transport and magnetic properties in good agreement with the experiments and electronic band-structure calculation.

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Published Online: 2009-9-25
Published in Print: 2005-3-1

© 2005 Oldenbourg Wissenschaftsverlag GmbH