Spectral and quantum-mechanical study of electronic structure of ultradispersed calcium hydroxyapatite

A. P. Shpak; V. L. Karbovskii; A. G. Vakhney; L. P. Kluyenko

A. P. Shpak Institute of Metal Physics of National Academy of Sciences
V. L. Karbovskii Institute of Metal Physics of National Academy of Sciences
A. G. Vakhney Institute of Metal Physics of National Academy of Sciences
L. P. Kluyenko Institute of Metal Physics of National Academy of Sciences

Анотація

The regularities of electronic structure of calcium hydroxyapatite samples of different genealogy were investigated by X-ray, IR spectroscopy methods and by quantum-mechanical calculations - X_a and LMTO (methods of the band theory). The evolution of valence band and charge states of atoms is described. It was established that distribution of p- and d‑electronic states of calcium in samples of calcium hydroxyapatite of different origin is practically identical. Beside a high ionic component, covalent and hydrogen bonds are present in calcium hydroxyapatite. The indirect metal-metal interaction is observed in a metal sublattice. It was shown that a sublattice of the phosphatic tetrahedra determines the shape and main features of a valence band of calcium hydroxyapatite. The lack of a part of calcium ions in the nonstoichiometric samples results in weakening of P-O bond within a mirror plane. An influence of the crystal-ultradispersed state transition on the shaping of X-ray emission spectra was first investigated. Considerable localisation of metal d-states is observed in the ultradispersed hydroxyapatite samples.

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