SIZE-DEPENDENT AND INTERFACE EFFECTS IN PROPERTIES
OF NANOSTRUCTURED MATERIALS

R.A. Andrievskiy
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
Chernogolovka, Moscow Region, Russia

      Size-dependent effects (SDE, i.e. the characteristic size influence of grains, particles, phase inclusions, pores, etc., on the properties of materials and substances) have been studied in physics, chemistry and materials science for a long time. The development of advanced nanotechnology manifests some new problems such as the SDE identification in nanometer interval. The SDE role in nanostructured (nanocrystalline, nanophase or nanocomposite) materials is of great importance both for fundamental considerations and modern technology. The effect of the nanoparticle/nanocrystallite size on surface energy, melting point, phase transformations and phase equilibriums is considered as applied to nanostructured materials. The role of size-dependent effects in phonon, electronic, superconducting, magnetic, and mechanical properties is also analyzed. Special attention is paid to the contribution of other factors such as the interface structure, grain boundary segregations, residual stresses and pores, non-uniform distribution of grain sizes and so on. The most interesting examples of the interface effect on the melting point (superheating) and strength/ductility of nanomaterials are described in detail. In particular, the importance of computer experiments and the study in situ of nanosubjects in electron microscopy is pointed. The little explored and unresolved problems are pointed and discussed.