Alexander Vul

New prospects and frontiers of nanodiamond clusters

The review is devoted to nanodiamond as a member of new nanocarbon allotropes. The past results related to the main features of detonation technology for producing nanodiamond are highlighted. Effects of technology on the structure of nanodiamond particles as well as functionalization of nanodiamond surface to chemical properties are discussed. The real structure of single nanodiamond particles has been critically reviewed and its aggregation problem emphasized. Several applications of nanodiamonds mainly as precursors for CVD diamond film growth, for forming new magnetic nanomaterials and field electron emitters are reviewed. As a result, the availability of nanodiamonds as attractive building blocks for nanotechnology is concluded.

Nanographene and Nanodiamond; New Members in the Nanocarbon Family

Nanographene and nanodiamond are new members of nanocarbons, which consist of nano-sized hexagonal and tetrahedral networks, respectively. The presence of edges and surfaces distinguishes nanographene and nanodiamond, respectively, from other nanocarbons owing to their structure dependent electronic features. Nanographene has an unconventional nonbonding pi-state (edge state) localized around its edge that is dependent on the edge geometry. The edge states, having localized spins, impart a nanographene-based molecular magnetic character. The structure and electronic/magnetic properties of nanodiamond vary depending on how the surface carbon atoms are terminated. Nanodiamond, with a naked surface, is subjected to structural reconstruction at the expense of sigma-dangling bonds. The hydrogenation of the surface is expected to give an electron reservoir function. The incompletely hydrogenated surface is magnetic with surface-induced spins.

The mechanism of autoelectron emission in carbon nanostructures

Abstract The model for description of the main field emission properties of carbon nanomaterials is proposed. The model is based on taking into account the electron–phonon drag effect in thermal gradient area in the emission site. The model does not require any additional expectations about special energy structure of the emission site. The quantity estimations based on the considering model are in good agreement with experimental results.

The Fundamental Properties and Characteristics of Nanodiamonds

The review is devoted to nanodiamond produced by detonation synthesis. The past results related to the main features of detonation technology for producing nanodiamond are highlighted. Effects of technology on the structure of nanodiamond particles as well as functionalization of nanodiamond surface to chemical properties are discussed. The real structure of single nanodiamond particles has been critically reviewed and its aggregation problem has been emphasized.

Magnetic Properties of Hydrogen‐Terminated Surface Layer of Diamond Nanoparticles

Abstract Nanodiamonds (ND) with the mean size about 4–5 nm is an interesting object for studying electronic and magnetic properties of diamond surface throughout its high specific area. Chemically modified ND particle is a very promising new unique material for applications in molecular nano‐electronics. Results of recent magnetic studies of pristine and hydrogen‐terminated ND samples, obtained by detonation technique, are reported and discussed. In addition to characteristic structural defects, originating from dangling C–C bonds of sp3 sites and located mainly in the interior of the nanocrystals, the hydrogen‐terminated ND crystals show a high concentration of excess free radicals (up to 1021 spin/g), which are due to structural defects (dangling C–C bonds) induced on the surface of diamond nanocrystals by hydrothermal treatment. Strong antiferromagnetic coupling is found between the spins localized on the surface.

Small-angle scattering from polydisperse particles with a diffusive surface

Particles with a diffusive surface, characterized by a deviation from the Porod power-law asymptotic behavior in small-angle scattering towards an exponent below −4, are considered with respect to the polydispersity problem. The case of low diffusivity is emphasized, which allows the description of the scattering length density distribution within spherically isotropic particles in terms of a continuous profile. This significantly simplifies the analysis of the particle-size distribution function, as well as the change in the scattering invariants under contrast variation. The effect of the solvent scattering contribution on the apparent exponent value in power-law-type scattering and related restrictions in the analysis of the scattering curves are discussed. The principal features and possibilities of the developed approach are illustrated in the treatment of experimental small-angle neutron scattering data from liquid dispersions of detonation nanodiamond. The obtained scattering length density profile of the particles fits well with a transition of the diamond states of carbon inside the crystallites to graphite-like states at the surface, and it is possible to combine the diffusive properties of the surface with the experimental shift of the mean scattering length density of the particles compared with that of pure diamond. The moments of the particle-size distribution are derived and analyzed in terms of the lognormal approximation.