Nuclear Magnetic Resonance Study of Ultrananocrystalline Diamonds

We report on a nuclear magnetic resonance (NMR) study of ultrananocrystalline diamond (UNCD) materials produced by detonation technique. Analysis of the 13C and 1H NMR spectra, spin-spin and spin-lattice relaxation times in purified UNCD samples is presented. Our measurements show that UNCD particles consist of a diamond core that is partially covered by a sp2-carbon fullerene-like shell. The uncovered part of outer diamond surface comprises a number of hydrocarbon groups that saturate the dangling bonds. Our findings are discussed along with recent calculations of the UNCD structure. Significant increase in the spin-lattice relaxation rate (in comparison with that of natural diamond), as well as stretched exponential character of the magnetization recovery, are attributed to the interaction of nuclear spins with paramagnetic centers which are likely fabrication-driven dangling bonds with unpaired electrons. We show that these centers are located mainly at the interface between the diamond core and shell.Comment: 25 pages, 7 figure

New data on the structure and hydrocarbon prospects of the Ukrainian Carpathians and their foreland

Volume: 170Start Page: 391End Page: 40

NATO Advanced Research Workshop on Synthesis, Properties and Applications of Ultrananocrystalline Diamond

Ultrananocrystalline diamond (UNCD) is one of the important members of the triad of nanostructured carbons, which includes fullerenes and nanotubes. UNCD with characteristic sizes of primary particles less than 10 nm occurs in two forms: as a dispersed powder made by detonation techniques and as a chemical vapor deposited film. This book for the first time combines results of research pursued by the two communities of scientists, which up to now, have been working rather independently and largely unaware of the vast synergistic relationships existing between them. It is particularly noteworthy that much of the Russian work on disperse UNCD is available here in English for the first time. The outstanding experts in the two fields are represented in this volume discussing the basic theoretical concepts underlying the synthesis and characterization of these nanomaterials and describing progress that has been made in several areas of applications such as nanocomposites, selective adsorbents, colloidal suspensions, microabrasives, lubricants, quantum dots, cold-cathodes for UNCD particles and MEMS, biosensors, electrochemical, and nerve prostheses, high temperature, highly rectifying diodes, FET’s, thermoelectrics for UNCD films. This Proceedings volume will be of interest to a wide audience of scientists and engineers and serve as an introduction to an important and rapidly evolving field of nanoscience and nanomaterials; as a text for a special topics graduate course; or as a starting point for those interested in the development of new approaches to problems that have hitherto defied solution for lack of suitable materials