Shrinking kinetics by vacancy diffusion of hollow binary alloy nanospheres driven by the Gibbs–Thomson effect

Abstract

The general treatment of the Gibbs–Thomson effect for a hollow nanosphere is presented. It allows for a vacancy composition profile across the nanoshell to be defined by a continuously decreasing function as well as by a continuous function with a minimum. The range for the controlling parameter of the vacancy motion within a binary alloy nanoshell is determined in terms of the phenomenological coefficients as well as the (measurable) tracer diffusion coefficients () of the atomic components. On the basis of a theoretical description and kinetic Monte Carlo simulations, it is demonstrated that for a hollow random binary alloy nanosphere with an equi-atomic (initially homogeneous) composition and neglecting the radial dependence of vacancy formation free energy, the controlling parameter of the shrinking rate in the limiting case can be estimated with reasonable accuracy as the geometric mean of the tracer diffusion coefficients of the atomic components.

Keywords:

• diffusion
• stability
• vacancies
• Monte Carlo
• binary alloy
• hollow nanospheres

Acknowledgments

We wish to thank the Australian Research Council (Discovery Project Grants Schemes) for its support of this research. One of us (E.V.L.) wishes to thank the University of Newcastle for the award of a Research Fellowship.