Zaporozhets T. Thermodynamics and multiscale modeling of diffusion-controlled processes in multiphase nanosystems

The thesis contains analysis of the applicability of classical diffusion theory to description of the diffusion-controlled processes in multiphase nanosystems with concentration gradients caused by the conditions of preparation, capillary effects, electric field. The study used the methods of theoretical description and computer simulation of mesoscopic and atomistic scales, its results agree with experiment. A characteristic feature of the objects is the non-equilibrium vacancy subsystem. It was established that the formation and shrinkage of hollow nano-shells represent just two stages of a single process of evolution of the "core | shell" structure as a result of competition and synergy of direct and inverse Kirkendall effects, Frenkel and Gibbs-Thomson effects. It is proved that there is a critical particle size below which pore formation inside the particle becomes impossible. Three-dimensional atomistic computer simulations confirmed a new mechanism of copper interconnects failures in electronic circuits: the formation of nanopores at the interface copper line and insulator, their movement along the interface under electron wind, temporal trapping and growth at the grain boundaries and their joints in thin films with bamboo structure, subsequent separation from the traps after exceeding the critical size. Concerning SHS (self-sustained high temperature synthesis), the inertia (finite relaxation time) of non-equilibrium vacancy subsystem in non-isothermic conditions and the effect of the preformed defect structure of the deposited multilayered foils on the flame temperature and velocity are taken into account. The new method of solving the inverse problem of SHS is suggested and partially checked - the estimation of effective diffusion and thermodynamic parameters of nanoscale multilayered foils on the basis of some special reference experiments.