Evidence for an equilibrium epitaxial complexion at the Au-MgAl2O4 interface

Abstract

Evidence for the existence of an equilibrium epitaxial complexion at the Au-MgAl2O4 interface has been observed. The growth of crystalline MgAl2O4 nanostructures, from a previously stable substrate in the presence of an Au overlayer and heat, is associated with this complexion. Prior to the nanostructures' self-assembly, Au nanoparticles crystalize, then reorient to align with the MgAl2O4 substrate. The presented results contradict earlier conclusions based solely on SEM studies of the final assembled nanostructures. Those results suggested that the MgAl2O4 grown pedestal and associated Au nanoparticle atop were both gold.

Temperature‐Induced Atomic Reconstruction At Au/MgAl2O4 Interfaces

“…[9] Besides, atomic reconstruction of interfacial structure has been experimentally observed in a lattice-matched system of Au/ MgAl 2 O 4 . [10,11] The thermally stable interface consists of sparsely arranged gold atoms with a well-defined periodicity. Such interface reconstruction could be ascribed to phase-like behaviors, referring to structure transitioning as a function of temperature and composition, because Au/MgAl 2 O 4 interface displays distinctive atomic arrangement under particular thermodynamic conditions.…”

“…Such interface reconstruction could be ascribed to phase-like behaviors, referring to structure transitioning as a function of temperature and composition, because Au/MgAl 2 O 4 interface displays distinctive atomic arrangement under particular thermodynamic conditions. X-ray diffraction analysis shows that the in-plane orientation of gold nanoparticles is random [11] for a thin film heated up to a temperature lower than 900 °C. Gold nanoparticles supported on MgAl 2 O 4 single crystals were prepared by a thermal dewetting method.…”

“…X-ray diffraction analysis shows that the in-plane orientation of gold nanoparticles is random [11] for a thin film heated up to a temperature lower than 900 °C. Gold nanoparticles supported on MgAl 2 O 4 single crystals were prepared by a thermal dewetting method.…”

“…These distributed gold nanoparticles [14] have a 〈111〉 fiber texture, i.e., {111} Au parallel to the substrate surfaces. X-ray diffraction analysis shows that the in-plane orientation of gold nanoparticles is random [11] for a thin film heated up to a temperature lower than 900 °C. When the thin film is heated up to >900 °C, the in-plane orientation of gold nanoparticles shows a preferred orientation [10] {111} Au ||{111} MgAl2O4 and 〈 〉 110 Au ||〈 〉 110 MgAl2O4 and its twins.…”

Interfacial Complexions and the Related Atomic Transport Behaviors in Gold-Oxide Systems

“…Recently, we discovered the formation of interfacial complexions between gold nanoparticles and oxide substrates, and an associated phenomenon of the spontaneous growth of nominally stable substrates underneath dewetted gold nanoparticles. Such phenomenon was repeatedly detected in Au/MgAl 2 O 4 [2][3][4], Au/TiO 2 , and Au/SrTiO 3 systems. It should be noted that these materials have been investigated as potential heterogeneous catalysts for energy-related reactions.…”