17 research outputs found
Equilibrium crystal shapes in the Potts model
The three-dimensional -state Potts model, forced into coexistence by
fixing the density of one state, is studied for , 3, 4, and 6. As a
function of temperature and number of states, we studied the resulting
equilibrium droplet shapes. A theoretical discussion is given of the interface
properties at large values of . We found a roughening transition for each of
the numbers of states we studied, at temperatures that decrease with increasing
, but increase when measured as a fraction of the melting temperature. We
also found equilibrium shapes closely approaching a sphere near the melting
point, even though the three-dimensional Potts model with three or more states
does not have a phase transition with a diverging length scale at the melting
point.Comment: 6 pages, 3 figures, submitted to PR
The overheating of lead crystals
Overheating of crystals has scarcely been reported unlike undercooling which is frequently observed. Admittedly the absence of overheating is the consequence of the crystal surface being covered by a liquid film (surface premelting) well under the bulk melting temperature. In the present letter we show that overheating is possible, and is actually observed (ÎT ⌠3°C), when the crystals are bounded by non wettable facets ({111} facets) separated by relatively small curved regions covered by their melt.Contrairement Ă la surfusion qui est trĂšs frĂ©quemment observĂ©e, la surchauffe de cristaux mĂ©talliques n'a que rarement Ă©tĂ© signalĂ©e. L'explication gĂ©nĂ©ralement avancĂ©e est que la surface des cristaux est recouverte d'un film liquide (prĂ©fusion de surface) bien avant que la tempĂ©rature de fusion volumique ne soit atteinte. Le but de cette courte note est de montrer que la surchauffe est possible et peut effectivement ĂȘtre observĂ©e (ÎT ⌠3°C) lorsque les cristaux sont limitĂ©s par des faces non mouillĂ©es (faces {111}) sĂ©parĂ©es par des parties courbes de trĂšs faible extension recouvertes de leur film liquide
Analysis of the critical behaviour of curved regions in equilibrium shapes of In crystals
Anomalous 422 diffraction spots from {111} flat gold crystallites: (111) Surface reconstruction and moiré fringes between the surface and the bulk
A Reflection Electron Microscopy Investigation of the Divergence of the Mean Correlated Difference of Step Displacements on a Si(111) Vicinal Surface
A Si(111) vicinal (misorientation ) is studied by in situ Reflection Electron
Microscopy at 1173Â K. A statistical study is done of the distances between pairs of
neighbours in a step train. The mean correlated difference of the step displacements from their mean
positions is determined as a function of . Evidence is given for the
roughness of the surface. A logarithmic behaviour of  versus is demonstrated
unambiguously up to . Quantitative agreement is found with the theoretical predictions of
Villain, Grempel and Lapujoulade. For more distant pairs of steps a different behaviour is
demonstrated: increases faster than Log, a fact already found by another author
A(1â4)-ÎČ-D-glucuronan excreted by a mutant of the <i>Rhizobium meliloti</i> M5N1 strain
International audienc