Transition volumes from multiply twinned particles to single crystals of supported Ag and Au nanoparticles

Abstract

Shape changes of Ag and Au nanoparticles supported on single crystal reconstructed SrTiO3(001) and (111) substrates were investigated using scanning tunneling microscopy. Both metals nucleate as multiply twinned particles (MTPs) and transform into face-centered-cubic single crystals (SCs) beyond a critical volume. On SrTiO3(001)- c(4 × 2) the critical volumes are measured as 141 ± 51 nm3 for Ag and 107 ± 23 nm3 for Au, whereas on SrTiO3(111)–(4 × 4)+(6 × 6) the critical volumes are 53 ± 26 nm3 for Ag and 26 ± 40 nm3 for Au. A much larger transition volume was observed on SrTiO3(001)–(2 × 1), where Ag remains as MTPs up to 3400 nm3, while Au nucleates as atomic monolayers instead of MTPs. This work demonstrates the significant impact of small variations of the surface structure of the substrate on the MTP–SC transition volume.