Theoretical prediction of impurity effects on the internally oxidized metal/oxide interface: the case study of S on Cu/Al2O3

Abstract

A detrimental sulfur effect on adhesion is known for iron- and nickel-oxide interfaces, but has never been reported on copper-oxide interfaces. Here we present a first-principles based study on the effects of temperature, interfacial stoichiometry, Al activity, and S segregation on the internally oxidized Cu/α-Al(2)O(3) interface. The calculated "interfacial phase diagram" for temperatures of interest suggests that the equilibrium interface structure is near the transition between Al-rich and stoichiometric phases. The Al-rich type interface is significantly stronger than the stoichiometric counterpart. The S effect on the Cu/α-Al(2)O(3) interface is obvious: S strongly segregates to both types of interface, degrades the adhesion (by ∼65%) and also reduces the size stability of alumina particles in Cu.

Interface-level thermodynamic stability diagram for in situ internal oxidation of Ag(SnO2)p composites

“…To face such challenges, first-principles based calculations have emerged as an indispensable tool for interface analyses in recent years. Specific application examples include Ni/Al 2 O 3 [5][6][7][8][9][10], Cu/Al 2 O 3 [10][11][12][13], Ag/ Al 2 O 3 [14,15], Ag/MgO [16], Ag/ZnO [17], and Cu/CeO 2 [18].…”

Theoretical prediction of microstructure evolution during the internal oxidation fabrication of metal-oxide composites: the case of Cu–Al2O3

“…The plane-wave basis sets were generated with valence configurations of Cu-3p 6 3d 10 4p 1 , Al-3s 2 3p 1 , and O-2s 2 2p 4 . 25 To model a heterogeneous interface, we chose to strain the Cu(111) and the a-Al 2 O 3 (0001) surfaces, each with the lowest surface energy in its bulk, into commensuration in a manner consistent with the lattice (stretching) strains in the metal found in the presence of dislocations. 40,41 The PAW-PW91 functional was finally chose for all subsequent calculations, for it yielded the best prediction of bulk Cu and Al 2 O 3 .…”

“…In our previous work, 25 we have evaluated the interface energies of Cu/Al 2 O 3 as a function of both a Al and p O 2 . Fig.…”

“…Upon oxygen exposure, the thermodynamically favored interface structure may change from a stoichiometric to a non-stoichiometric termination (Al-or O-rich). 25. 25, must be also considered.…”

“…[1][2][3][4][5][6][7][8][9] To optimally design and fabricate these interfacial materials systems, one requires a fundamental understanding of the thermodynamics and kinetics of the relevant interfaces and how they correlate with fabrication processing parameters. [19][20][21][22] Specific application examples include Ni/Al 2 O 3 , [19][20][21][22][23][24] Cu/Al 2 O 3 , [24][25][26][27] Ag/Al 2 O 3 , [27][28][29] Ag/MgO, 30 Ag/ZnO, 31 and Cu/ CeO 2 . HRTEM can offer the unique ability to observe an interface directly in real space at the atomic scale.…”