Regensburg 2002 – wissenschaftliches Programm

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M: Metallphysik

M 20: Symposium on Structurally Complex Alloy Phases II (SCAP II)

M 20.3: Vortrag

Donnerstag, 14. März 2002, 12:00–12:30, H16

Structurally complex intermetallics, where are the atoms and why? — •Walter Steurer — Laboratory of Crystallography, ETH Zurich, CH-8092 Zurich, Switzerland

The crystal structures of the metallic elements range from the simple open cP1-Po structure, stabilised by relativistic spin-orbit effects, to the exceptionally complex cI58- Mn structure, resulting mainly from the very narrow 3d bands and antiferromagnetic interactions of manganese. Binary intermetallic phases show increased complexity. Giant unit cells with thousands of atoms, such as for instance the heavy-fermion compound mC7448-YbCu4.5 are no scarcity. Even more complex becomes the structural world of ternary and higher intermetallics. The unit cells may reach the size of the crystal as in the case of quasicrystals or incommensurately modulated crystals. In many cases, structural entities can be identified with high (pseudo)symmetry or scaling symmetry. These very complex structures can only be solved by using complementary imaging, spectroscopic and diffraction methods.