ATOMIC PROCESSES IN THE DEPOSITION AND SINTERING OF ULTRAFINE METAL PARTICLES ON MGO(001) AS INVESTIGATED BY MOLECULAR-DYNAMICS AND COMPUTER-GRAPHICS

Atomic processes in the deposition and sintering of ultrafine Pd and Au particles on MgO(001) plane were investigated by molecular dynamics (MD) and computer graphics (CG). In contrast to the behavior of bulk Pd crystal, Pd atoms in the Pd cluster exhibited high mobility even at 300 K. In agreement with the mobility of the Pd cluster, the shape of the Pd cluster changed significantly during the deposition process of the Pd cluster on the MgO(001) plane, while the position of Mg and O ions on the MgO(001) plane did not change significantly. These behaviors of the Pd cluster are similar to those of Au cluster reported previously. The sintering process of two Pd-32 clusters on the MgO(001) plane was also simulated at various temperatures. In contrast to the sintering behavior of two Au-32 clusters on the MgO(001) plane, the coagulation of two Pd-32 clusters did not take place at 300 K but at a higher temperature such as 1300 K. Furthermore, the effect of modification of the substrate surface on the structure of the metal cluster was investigated for monatomic Au and Pd quantum wires. When a monatomic Au quantum wire was located on the smooth MgO(001) surface, the shape of the monatomic quantum wire of Au was rapidly destroyed to form a disordered structure of Au atoms. When the monatomic quantum wire of Au was located on a MgO(001) surface with a monatomic groove along the [110] axis, the structure of the monatomic quantum wire was stably maintained. The crystallographic fit between metal and substrate was found to provide one of the reasons for the stability of the monatomic quantum metal wire.