posted on 2018-03-06, 00:00authored byYuntao Cui, Fei Liang, Zhenze Yang, Shuo Xu, Xi Zhao, Yujie Ding, Zheshuai Lin, Jing Liu
Interface
interaction can strongly modify contact angle, adsorption energy,
interfacial tension, and composition of the contact area. In particular,
the interfaces between gallium-based liquid metal (LM) and its intermetallic
layer present many mysterious and peculiar wetting phenomena, which
have not been fully realized up to now. Here in this study, we found
that a gallium-based liquid metal droplet can quickly transform into
a puddle on the CuGa2 surface through a spreading–wetting
procedure. The mechanism lying behind this phenomenon can be ascribed
to the formation of an intermetallic CuGa2 on Cu plate
surface, which provides a stable metallic bond to induce the wetting
behavior. For a quantitative evaluation of the interface force, a
metallic bond-enabled wetting model is established on the basis of
the density functional theory. The first-principles density functional
calculations are then performed to examine the work function, density
of states, and adsorption energy. The predicted results show that
the work function of CuGa2 (010) is approximately 4.47
eV, which is very comparable with that of pure liquid Ga (4.32 eV).
This indicates that the valence electrons between Ga and CuGa2 slab can exchange easily, which consequently leads to the
strong valence electron hybridization and metallic bond. In addition,
the adsorption energy of a single Ga atom on CuGa2 (010)
slab has a larger value than In and Sn. The tested metallic bond wetting
force at the interface is proportional to the average adsorption energy
of the gallium-based LM adatom, and increases with the rising content
of gallium. The simulation results demonstrate excellent consistency
with the experimental data in this work.