interface (rus. граница раздела) — transition layer between two phases or contact surface between two grains in polycrystalline materials.

Description

The properties of atoms and molecules at interfaces differ from the properties of atoms and molecules in the bulk of a phase or material due to the difference in their environment (see also surface). Therefore, the interface properties of substances and interface phenomena are studied by a special branch of physics and chemistry. The surface effects have special importance in nanomaterials, where the share of the surface is very large and can determine the properties of the entire material (see, for example, Hall-Petch relation).

In the simplest case a nanomaterial composed of atoms of one kind contains two components that differ in structure: ordered grains (crystallites) and interfaces (intergrain boundaries). The interface structure is determined by the type of interatomic (metal, covalent, ionic) interaction and the mutual orientation of neighbouring grains (crystallites). Interfaces of compact nanomaterials can contain such types of defects as: single vacancies, vacancy agglomerates or pores formed at triple junctions of crystallites or in the place of a missing crystallite. Possible effects in the interfaces of compact nanomaterials include elastic stresses that locally distort the crystal lattice of the grains around their boundaries, and grain-boundary dislocations. Annealing of polycrystalline nanomaterials leads to the relaxation of their interfaces.

An important example is given by the semiconductor heterostructures, where the interface (or, in this case, a heterojunction) between two semiconductors differing in chemical composition serves as a technical device. In heterostructures with very sharp interfaces, neighbouring heteroboundaries are situated so close to each other that in the gap between them a decisive role belongs to dimensional quantum effects.

Author

  • Gusev Alexander I.

Sources

  1. Gusev A. I. Nanomaterials, Nanostructures, and Nanotechnologies (in Russian) // Fizmatlit, Moscow (2007) - 416 pp.
  2. Gusev A. I., Rempel A. A. Nanocrystalline Materials. — Cambridge: Cambridge International Science Publishing, 2004. — 351 p.

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