General model for the kinetics of solute diffusion at solid-solid interfaces

Abstract

Solute diffusion through solid-solid interfaces is paramount to many physical processes. From a modeling point of view, the discontinuities in the energy landscape at a sharp interface represent difficulties in predicting solute diffusion that, to date, have not been solved in a consistent manner across length scales. Using an explicit finite volume method, this work is the first to derive numerical solutions to the diffusion equations at a continuum level while including discrete variations in the energy landscape at a bicrystal interface. An atomic jump equation consistent with atomistic descriptions is derived and scaled up into a compendium of model interfaces: monolayer energy barriers, monolayer interfacial traps, multilayered traps, and heterogeneous interfaces. These can track solute segregation behavior and long-range diffusion effects. We perform simulations with data for hydrogen diffusion in structural metals, of relevance to the assessment of the hydrogen embrittlement phenomenon, and point defects in electronic devices. The approach developed represents an advancement in the mathematical treatment of solute diffusion through solid-solid interfaces and an important bridge between the atomistic and macroscopic modeling of diffusion, with potential applications in a variety of fields in materials science and physics.

Preparation and adsorption properties of magnetic chitosan/sludge biochar composites for removal of Cu2+ ions

“…The adsorption sites on the surface of the Fe 3 O 4 @CTS/SBC composite adsorbent were mainly occupied by Cu 2+ , which began to enter the micropores of the composite adsorbent and was adsorbed by the micropores. At the third stage of adsorption, the adsorption sites on the surface and inside the pores of the Fe 3 O 4 @CTS/SBC composite adsorbent were basically saturated, and the adsorption reached an equilibrium state 38 . Based on the particle diffusion model, it could be concluded that the adsorption of Cu 2+ by the Fe 3 O 4 @CTS/SBC composite adsorbent was not only a chemical chelation, but also an intraparticle diffusion process.…”