In principle, all the properties of bulk materials can be determined provided that the composition and the structure of the material are sufficiently well defined. But, it is easy to realize that the properties at a solid surface are altered because of the very presence of the surface constituting a fundamental discontinuity. When the size of the solid is decreased down to the nanometer scale, the nanoparticles can be considered as surfaces in three dimensions and the relationships between bulk structure and material properties are no longer valid. In nanostructured coatings, the constitutent phase or the grain structure may have sizes of the order of 10 nm or less, leading to a high number of atoms either at the external surface or at the grain boundaries. Besides, the material synthesis history and the preparation method of hte layers govern the surface structure and the surface composition of coatings. Therefore, precise surface characterization is a strong requirement to control the surface properties and to further improve the nanostructured coating performances.
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