The structural evolution, epitaxy, and sublimation temperature of silver nanoclusters (NCs) on TiO2 (110) surfaces prepared in two different ways are reported here based on a combination of in situ reflection high energy electron diffraction characterization and ex situ electron imaging. It is shown that silver NCs deposited at room temperature on oxidized TiO2 (110) surfaces are unable to form a single epitaxy prior to sublimation. When heated close to sublimation, two particle orientations dominate: (111) Ag∥(110) TiO2, [-110] Ag∥ TiO2 and (112) Ag∥(110) TiO2, [-110] Ag∥ TiO2. Single twinned silver NCs are found to be stable even at temperatures close to sublimation. On the other hand, silver NCs prepared similarly on reduced TiO2 (110) surfaces behave very differently when heated to higher temperatures. On the reduced surface, the NCs are able to evolve into a single epitaxy-(111) Ag∥(110) TiO2, [-110] Ag∥ TiO2. The sublimation temperature for silver NCs on the reduced surface is found to be less than those on the oxidized surface by about 35°. The epitaxy formed by annealing is the same as the one formed by depositing silver onto reduced TiO2 (110) at 350 °C (>0.5 Tm of Ag).
ASJC Scopus subject areas
- Physics and Astronomy(all)