A. E. Madison

Structure of Nanosized Zirconia Centaur Particles

The crystal structure of structurally inhomogeneous zirconia particles (centaurs) is investigated. It is shown that centaur particles consist of monoclinic and tetragonal fragments which obey rigorous orientational relationships.

Investigation of the Structure of Zirconia Nanoparticles by High-Resolution Transmission Electron Microscopy

The structure of zirconia nanoparticles is investigated by high-resolution transmission electron microscopy (HRTEM). The structurally inhomogeneous nanoparticles with coherent interfaces (centaurs) are observed. The orientation relationships of the conjugated structures are determined.

Structure of Nanoparticles: I. Generalized Crystallography of Nanoparticles and Magic Numbers

The structure of a nanoparticle of a material is generally determined by the chemical composition of the material, the number of atoms in the particle, and the character of the chemical interaction between atoms. Nanoparticles can have a regular crystalline structure, can be amorphous, or can form a pseudoclose packing undescribable by any of the crystallographic space groups. For each of these structural states of a nanoparticle, there is a certain set of numbers of the atoms involved in the particle that corresponds to optimum stable configurations. These numbers are usually called the magic numbers.

Structure of Nanoparticles: II. Magic Numbers of Zirconia Nanoparticles

The concepts of generalized crystallography and the generalized geometric approach are applied to the description of the structural features of zirconia nanoparticles. The magic numbers are counted for polymorphic (cubic, tetragonal, and monoclinic) zirconia modifications.

Structure of nanodiamonds

The structure of nanodiamonds is considered within the model of icosahedral nanoparticles with a local diamond-like order and a shell structure. The diffraction from nanoparticles with noncrystallographic (in particular, icosahedral) packings of atoms is analyzed. It is demonstrated that the method proposed for calculating the intensity of coherent scattering by clusters of identical polyatomic aggregates is applicable to the entire diversity of carbon structures existing in the nanoworld.

Specific Features of Diffraction by Nanoparticles

The influence of the shape and size of nanoparticles on the scattered-intensity distribution in the reciprocal space, the shape of the spot in the electron diffraction pattern, and the X-ray diffraction line profile is investigated. It is demonstrated that the X-ray diffraction and electron diffraction data allow one to obtain valuable information on the structure of nanoparticles.

Structural transformations in carbon nanoparticles

The structure of icosahedral carbon (diamond and onion-like) nanoparticles is discussed. It is shown that, in carbon nanoparticles, the reversible structural transformations of icosahedral particles into particles with a shell structure can occur without breaking of bonds or disturbance of their topological integrity. New structural models are proposed and analyzed for carbon nanoparticles. The diffusionless mechanism of reversible transformations between diamond-like and onion-like particles is proposed for the first time.