Chapter Diffusion in Materials
Diffusion is the random movement of molecules or small particles taking place due to the motion caused by thermal energy [1-20]. It is a general property of matter linked with the propensity of systems to occupy all accessible states . In a more simple way, diffusion is a spontaneous tendency of all systems to equalize concentration, if any external infl uence does not impede this process. Specifi cally, atoms, molecules, or any particle chaotically moves in the direction where less elements of its own type are located.