ELECTRONIC STRUCTURE AND PROPERTIES OF APATITE-LIKE CALCIUM-BASED COMPOUNDS, INITIATED BY NANODIMEMSION, BIOGENIC FACTOR AND ISOMORPHIC SUBSTITUTION OF CALCIUM BY 3D-METALLS

Calcium apatites due to their physicochemical properties, high biological activity deservedly attract special attention not only in view of purely scientific interest, but also in connection with the use of drugs synthesized on their basis. in practical traumatology. dentistry, i.e. in those areas of medicine that are relevant to the treatment and restoration of bone tissue. As a rule, the basic elements are samples of nanometric dimensions. Electronic properties, features of chemical bond, structural parameters demonstrate high sensitivity to size reduction. In this paper, the nature of chemical bond, redistribution of electron density in energy and real space, isomorphically substituted hydroxyapatites based on calcium are studied with the complex application of such methods as photoelectron and X-ray spectroscopy, nuclear magnetic resonance, atomic force spectroscopy.

Valence Electron Structure Analysis of Intrinsic Hardness for Diamond and c-BN

Based on the Pauling’s nature of chemical bond, the valence electron structures of diamond and c-BN crystals have been constructed. Then the relationship between covalent bond and glide plane system is analyzed. The results show that the hardness of diamond and c-BN is correlated to the covalent electron structure and the slip system of crystals. The hardness for diamond and c-BN so large is explained satisfactory form valence electron structures.

VALENCE ELECTRON STRUCTURE ANALYSIS OF INTERFACE OF FeAl/TiN COMPOSITES

Based on Pauling's nature of chemical bond, the valence electron structures of TiN and FeAl have been constructed, and the relative electron density differences (REDD) between the low index plane of TiN and FeAl , respectively, have been calculated. [110] FeAl //[110] TiN crystallography orientation has been set up from the minimization of the electron density difference across the interface. From the viewpoint of improving the mechanical properties of composites, the formation of such structures must been engineered in the fabrication processing.

The nature of chemical bond in trioxide Mi-UO3

Low-energy X-ray photoelectron and conversion electron spectra from uranium trioxide were measured, and calculations were done for the [UO2O4]-6 (D4b) cluster which reflects the structure of uranium close environment in MI-UO3 in the non-relativistic and relativistic Xa-DVM approximation. This enabled a satisfactory qualitative and in some cases quantitative agreement between the experimental and theoretical data, and interpretation of such spectra. Despite the traditional opinion that before participation in the chemical binding, the U5f electrons could be promoted to the higher (for example - U6d) levels, it was theoretically proved and experimentally confirmed that the U5f electrons (about two U5f electrons) are able to participate directly in the chemical bond formation in uranium trioxide. The filled U5f states proved to be localized in the outer valence molecular orbitals energy range 4-9 eV, while the vacant U5f states were generally localized in the low-energy range (0-6 eV above zero). It was experimentally shown that U6p electrons not only participate effectively in the inner valence molecular orbital formation but also participate strongly (more than 1 U6p electron) in the formation of die filled outer valence molecular orbitals.

Shape and Size Effect on Ultrafine Metallic Particles

ABSTRACTThe effect of size and shape on the electronic state of ultrafine metallic particles is described with the critical review of so far proposed experimental and theoretical results. The temperature dependence of the spin susceptibility of small metal particles is presented as function of size, shape, spin-orbit interaction of the elements, and magnetic field strength. Based upon a proposed formula, the spin susceptibility of small Mg particles is precisely analyzed with the view point of shape effect. It is emphasized that the exogenous impurities have crucial effect. on the magnetic properties of small metal particles. It is clarified that the confusion in the magnetic experiments originates from the extrinsic magnetic effect. The deviation of the nature of chemical bond in small size systems from that in bulk is briefly outlined.