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Magnetic resonance techniques, namely Electron Paramagnetic Resonance (EPR) and solid state Nuclear Magnetic Resonance (NMR), are powerful non-destructive tools for studying electron-nuclear and crystalline structure, inherent electronic and magnetic properties and transformations in carbon-based nanomaterials. EPR allows to control purity of ultradispersed diamond (UDD) samples, to study the origin, location and spin-lattice relaxation of radical-type carbon-inherited paramagnetic centers (RPC) as well as their transformation during the process of temperature driven diamond-to-graphite conversion. Solid state NMR on 1H and C nuclei provide one with information on the crystalline quality, allows quantitative estimation of the number of different allotropic forms, and reveals electron-nuclear interactions within the UDD samples under study. Results of recent EPR and C NMR study of pure and transition metal doped UDD samples, obtained by detonation technique, are reported and discussed. In addition to characteristic EPR signals, originated form para- and ferromagnetic impurities and doping ions, the UDD samples show a high concentration of RPC (up to 1020 spin/gram), which are due to structural defects (dangling C-C bonds) on the diamond cluster surface. EPR sample’s vacuumization experiment in conjunction with precise SQUID magnetization measurements allowed concluding that each UDD particle carries a single spin (dangling bond) per each from 8 crystal (111) facets bounded the particle.

We report infrared absorption spectra of explosion nanodiamonds and compare these with spectra of -C:H films prepared by laser ablation. Similarities between these spectra are discussed. In particular, we find that a feature near 1620 cm in nanodiamond particle spectra can be associated with the presence of C=C groups. This is supported by the observation of bands arising from CH. We suggest that these groups are created by surface reconstruction on these extremely small particles that tends to de-emphasize tetrahedral bonding in the surface layer.

Chlorinated derivatives of methane were used for conversion of Si, Ge, Ti, Sn, Fe, SiC, GaSb, FeSi, and ZrN to microporous nanocarbons. The conversion represents the substitution of non-carbon atoms in the lattice by carbon atoms at 500–1100°C. Carbon nanofibers were produced from SiC whiskers, using both chlorine and chlorinated methane derivatives. The chlorination and the properties of the nanofibers were found to depend on the twinning and inversion of the type of SiC conductivity. We observed the formation of nanocrystalline diamond-like carbon. The conversion of carbides and other inorganic substances to carbon nanostructures was possible in the treatment with chlorinated methane derivatives.

Composite xerogels based on a phosphosilicate matrix filled with nanodiamonds were synthesized by sol-gel processing. The crystalline and fractal characteristics of the initial nanopowders were obtained using wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) techniques. Proton-conducting nanocomposite membranes of fuel cell applications were fabricated from the xerogels. The WAXS data on the nanodiamonds show diffraction patterns characteristic of graphitized ultradisperse nanodiamonds or pure nanodiamonds. The Beaucage plots of the phosphosilicate-nanodiamond composites show a multi-level fractal structure of the type of the surface fractal/mass fractal. The fractal characteristics such as the size and the gyration radius of the aggregates were calculated from the plots. The conductivity-frequency curves show that the conductivity is high and increases with the nanodiamond content in the composites.

We develop an industrial system for a large scale production of ultradispersed diamond (UDD). The system includes set-ups for synthesis and chemical purification of detonation soot as well as experimental shops for additional and deep purification and modification of UDD.

In detonation synthesis, we use “wet” and “dry” technologies when explosion is carrying out in water and gas atmosphere correspondingly. For purification of detonation soot we use the chemical treatment in bynitric-acid aqueous solution at high pressure and temperature in an autoclave. The process occurs in a continuous regime with a technological cycle of 4–6 days, providing large UDD batches of uniform and reproducible quality. The chemical treatment occurs in 5 temperature zones by varying the velocity of the reactive suspension in laminar and intermediary flow regimes. Non-carbon accumulation in the UDD powder and impurities in the waste acid have been studied. Methods for additional purification of UDD from soluble and insoluble impurities and admixtures are suggested, together with ways of decreasing titanium corrosion.

Composite chromium-diamond electroplating is one of the most UDD consuming technologies among UDD applications. The exploitation includes periodic cleaning of the chroming bath from accumulated anodic sludges and contaminants. During the cleaning, the UDD must be extracted from the sludges and regenerated for re-use. We have suggested technique for UDD regeneration from sludges containing up to 80% of insoluble Cr, Pb and Sb compounds. The process includes mechanic, colloidal-chemical and chemical treatments which provide a fairly pure material only with 1–3% of noncarbon; the calculated diamond yield is 85–90%. We have analyzed the contaminants in regenerated UDD for their dispersion, sedimentative and aggregative stability, adsorptive and structural characteristics of the surface. Regenerated diamond is applicable for re-use in electroplating technologies.

Technology of the synthesis of detonation soot, two alternative ways of their post-synthesis purification and related characteristics of the resulting detonation nanodiamond (DND) particulate are discussed.

A pilot process of UDD chemical purification UDD using a rocket oxidizer of “melange” type with expired storage term was developed and put into practice. The process is based on oxidation of diamond-containing blend by nitric acid solutions in the temperature range of 110–320°C and pressure up to 10 MPa. Methods of preliminary treatment and purification of the oxidizer are developed. The regimes of high-pressure and temperature treatment of diamond-containing mixture with the account of elevated chemical activity of the oxidizer are optimized. Specific impurities in the oxidizer and their behavior at high temperature and pressure are studied, and methods of impurity separation from the desired product are suggested. Corrosion effect of the oxidizer and its products on suggested high-pressure equipment is investigated.

Composite electrochemical coatings (CEC) deposited from three basic gilding solutions after addition of 0.1–10 of three UDD modifications were studied. The UDD content of in the CEC was varied in the range of 0.2–0.8% depending on the electrolyte composition, the UDD concentration and modification. Microhardness of the CEC is found to increase by 50–70% due to UDD and the microhardness dependence on the UDD concentration may be monotonic or sharp, depending on the modification used. We suggest an effective electrolyte composition with less than 3 of the best UDD modification. Composite electrolyte is characterized by high stability in exploitation, high colloid stability of UDD zol, and good physical, mechanical, protective, and decorative properties of CEC. The coating has a microhardness of 1.5–1.8 GPa, a relative wear resistance of 1.5–2.3, as compared to samples containing no diamond. An average thickness of the continuous layer (on polished substrate or a glance Ni interlayer) is 0.15–0.2 µm.

Nanometer scale diamond tip emitters for cold cathodes are being developed as (a) vertical and (b) lateral diamond vacuum field emission devices. These diamond field emission devices, diode and triode, were fabricated with a self-aligning gate formation technique from silicon-on-insulator wafers using variations of silicon micropatterning techniques. High emission current, > 0.1A was achieved from the vertical diamond field emission diode with an indented anode design. The gated diamond triode in vertical configuration displayed excellent transistor characteristics with high DC gain of ∼ 800 and large AC output voltage of ∼ 100 V p-p. Lateral diamond field emission diodes with cathode-anode spacing less than 2 μm were fabricated. The lateral diamond emitter exhibited a low turn-on voltage of ∼ 5 V and a high emission current of 6 μA. The low turn-on voltage (field ∼ 3 V/μm) and high emission characteristics are the best of reported lateral field emitter structures. We are also examining particulate nanodiamond for thermal conductivity enhancement of dielectric oils. We have observed that a dispersion of nanodiamond (particle size circa < 5 nm) can increase the overall thermal conductivity of cooling oils such as used in power transformers by over 25%.