Regensburg 2000 – wissenschaftliches Programm
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M: Metallphysik
M 8: Struktur und Umwandlung III
M 8.10: Vortrag
Dienstag, 28. März 2000, 17:45–18:00, H16
Change from a Bulk Discontinuous Phase Transition in V2H to a Continuous Transition in a Defective Skin Layer — •Johann Trenkler1, Peter Wochner1, Hiroshi Abe2, George Reiter3, Paul Chow3, and Simon Moss3 — 1Max-Planck-Institut fuer Metallforschung, 70569 Stuttgart — 2National Defense Academy, Yokahoma, Japan — 3University of Houston, Houston, TX 77204, USA
We have observed two length scales in the critical x-ray diffuse scattering (CDS) from a VH0.525 crystal above the β1-β2 phase transition where a sharp Lorentzian profile in the CDS was superimposed on a broader one. While no sharp component appeared in transmission geometry with high-energy x-rays, no broad component was detected in an experiment confined to the defective near-surface skin layer. In this talk, we will discuss the scaling and crossover behavior of exclusively the defective skin layer or the pure bulk. We further discuss the change of the order of the phase transition from the bulk to the skin layer which is associated with a change in the sign of the fourth order term in the Landau free energy expansion.