Phase equilibrium in nanometer-sized particles

The phase equilibrium in nanometer (nm)-sized particles has been studied by transmission electron microscopy using particles in the Au-Sn system. When tin atoms are vapor-deposited onto nm-sized gold particles, rapid dissolution of tin atoms into gold particles takes place and as a result particles of an Au-rich solid solution, of a topologically-disordered amorphous-like alloy and of the AuSn compound are formed, depending upon the concentration of tin. Remarkable enhancement of solubility has been observed in the Au-rich solid solution and the AuSn compound. The topologically-disordered amorphous-like phase, which appears in the two-phase region of the phase diagram for the bulk alloy, may be stabilized due to the lattice softening in nm-sized particles.