Equilibrium phase diagrams of isolated nano-phases

摘要

Materials processing and fabrication shows a strong trend toward manipulation of materials at ever de creasing sizes. This is especially true in microelectron ics. Once the size of a material extends below the sub- micrometer level significant changes in the properties and behavior of materials emerges. It is sometimes diffi- cult to determine if the changes observed at this nano- scale are a result of the process variables or are inherent to material because of its small size. In order to address this difficulty with regard to crystal structure and compo- sition, phase diagrams as a function of size would be particularly useful. In the present paper experimental da- ta on phase equilibria are presented as well as a thermo- dynamical analysis based on capillarity effects from sur- face curvature. The analysis and experimental data for binary phase diagrams agree with one another and show that isolated particles of less than 100 nm exhibit sub- stantial decreases in liquidus temperature, factors of more than 10 increase in solubility, and narrowing of the two-phase fields. The details of the thermodynamic mod- el and its predictive powers are presented along with a threedimensional phase diagram which has temperature- cOmpOsition-slze as its axes.