Gold-assisted growth of oxide bases underneath dewetted gold nanoparticles

Highlights: • Pyramid-shape oxide bases grow underneath gold particles at elevated temperatures. • The growth of bases is related to the change in surface and interface energy. • The Au-SrTiO₃ interface consists of Au on Ti-terminated (111)-surface. -- Abstract: The self-assembly of oxide bases, from nominally stable oxide substrates, underneath dewetted gold nanoparticles have been replicated in Au-SrTiO₃, the same as the recently-reported case in Au-MgAl₂O₄. Both grown bases have the same morphology and crystallographic characters, and are associated to the formation of strong interfaces. To reveal the underlying growth mechanism, we establish a thermodynamic model, estimating that the decrease in the total surface and interfacial energy of gold-oxide nanostructures cannot be compensate the energy increase for growing bases. Other factors, including the surface energy decrease during gold vaporization, are suggested to be partially responsible for the base growth. Our results suggest new possibilities in controlling the synthesis of gold-oxide nanostructure.