In situ observations of crystalline-to-liquid and crystalline-to-gas transitions of substrate-supported Ag nanoparticles

The phase transitions of silver nanoparticles on graphite and alumina substrates have been investigated using in situ high-resolution transmission electron microscopy. It was revealed that no crystalline-to-liquid transition, only a crystalline-to-gas transition, took place in graphite-supported silver nanoparticles prior to the complete disappearance of the nanoparticles; crystalline-to-liquid transition did take place in alumina-supported silver nanoparticles. The substrate-induced difference in the phase transition behavior is discussed on the basis of a thermodynamic model.