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Title: Coupling between bulk thermal defects and surface segregation dynamics
Surface segregation is a phenomenon that depends on the delicate interplay between thermodynamic driving forces and kinetic obstacles, for which elevated temperature is often needed to enhance the atom mobility and reach equilibrium. Using the classic system of Cu3Au(100) under the non-isothermal conditions, herein we show an adatom process underlying transient surface segregation dynamics through the temperaturechange-driven creation and annihilation of thermal vacancies in the bulk and the resulting bulk/surface mass exchanges. This is demonstrated by monitoring the surface composition evolution of Cu3Au(100) with temperature changes between 250 °C and 500 °C, showing that the increase in temperature decreases monotonically the surface Au concentration as a result of the transfer of more Cu than Au from the bulk to the surface to form Cu-rich clusters of adatoms. Such a bulk thermal defect effect is expected to be universal in inducing the disparity in the bulk/surface mass exchanges of dissimilar atoms in multicomponent materials because of the inherent differences in the vacancy formation energies of the constituent atoms.  more » « less
Award ID(s):
1905422 1905572
NSF-PAR ID:
10331678
Author(s) / Creator(s):
Date Published:
Journal Name:
Physical review
Volume:
104
Issue:
08
ISSN:
2469-9950
Page Range / eLocation ID:
085408
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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