Variation of surface composition and sintering of binary Pd70Ag30 nanoparticles

The variation of surface composition and sintering of the binary Pd70Ag30 nanoparticles prepared by chemical reduction were studied. The composition of the as-prepared Pd70Ag30 nanoparticles across the diameter is inhomogeneous due to different reduction potentials of Pd and Ag. Upon heating, Ag will migrate to the surface because of its lower surface energy. Surface modification results in variation of surface composition during the sintering process. Stearic acid acts as a grain growth inhibitor. The migration of Ag to the surface is suppressed and the sintering is retarded. Modification by polyethylene glycol leads to more migration of Ag atoms from the core to the surface. This makes the nanoparticles easier to sinter.