Suchergebnisse

Applying a set of structural-spectroscopic methods of analysis we have studied the relationships between the structure, morphology and sorption characteristics of the samples of nanocrystalline carbonate-substituted hydroxyapatite (C-HAP) synthesized with the use of biogenic calcium source (poultry eggshell) obtained by the chemical deposition from a solution. With the use of X-ray diffractometry and X-ray microanalysis it was found that the appearance of impurities in the structure of synthesized material was due to their presence in calcium carbonate of the poultry eggshell and this could result in the changes of parameters in the elementary crystal cell of hydroxyapatite without formation of the additional phosphate phases. Optical and ESR spectroscopy allowed us to find that in the presence of the inherited set of impurities inclusion of carbonate ions into the structure of our synthesized hydroxyapatite takes place with the formation of C-HAP of B-type. An increase in the content of phosphate groups PO 4 in the process of the materials synthesis in the atmosphere results in the reduction of that of one of structurally bound CO 3 groups. A decrease in the pH value in the solution during the synthesis connected with the increase in the PO 4 3− anions content leads to the change of morphology of the C-HAP samples due to the increase in the size of intracrystalline defects – nanopores at the surface of C-HAP nanocrystals. Such a change in the morphology of the materials resulted in the changes of the sorption characteristics of the samples that were measured by means of thermal desorption of nitrogen technique. The specific surface area of C-HAP powders determined by means of the BET technique was ∼55.5 ± 0.9 m 2 /g, exceeding by several times that of the known analogs. Meanwhile, despite the developed surface the C-HAP samples remained rather stable in the atmosphere of the saturated water vapour and the main losses under polarization are related to Maxwell-Wagner losses. Analysis of characteristics for the C-HAP samples obtained from a biogenic source of calcium demonstrated their potential significance for obtaining of biomimetic materials imitating structure, morphology and anisotropy of the native hard tissues of the human tooth. © 2019 The Authors ; The study was performed under the support of the grant Russian Foundation for Basic Research (RFBR) № 18-29-11008 mk. The work was partly supported by Ministry of Education, Youth and Sport of the Czech Republic (grant numbers LM2015088 , LO1409 ) and Contract No. 02.A03.21.0006 of the Government of the Russian Federation . Appendix A

The purpose of this work is to establish of the bound oxygen effect on the phase composition of the Semi-Insulating Polycrystalline Oxygen-doped Silicon (SIPOS) films by means of three independent methods: X-ray diffraction (XRD), Ultrasoft X-ray Emission Spectroscopy (USXES) and Raman spectroscopy, also on their electrophysical properties, depending on the relative oxygen content in the gas mixture flow (γ=N2O/SiH4) of the plasma reactor during the chemical vapor deposition of submicron SIPOS layers on monocrystalline silicon wafers. The increase in the oxygen content in SIPOS layers from γ=0 to maximum at γ=0.15 leads to the reduction of Si nanocrystals size from ~75 nm to 2–5 nm, submerged in amorphous matrix. Oxygen is contained in the bound form of silicon-oxygen clusters SiOSi3 type in the amorphous silicon matrix without SiO2 formation. These nonlinear qualitative and quantitative changes in the atomic structure of the SIPOS layers under the influence of bound oxygen increase not only the resistivity of the films by two orders of magnitude but also the activation energy of conductivity in comparison with silicon at the temperatures above room temperature. © 2020 Elsevier Ltd ; Russian Foundation for Basic Research, RFBR: 19-42-363013 ; MD-42.2019.2 ; Ministry of Science and Higher Education of the Russian Federation ; The reported study was funded by RFBR and Government of Voronezh region according to the research project № 19-42-363013. ; The part of work was carried out with the support of the Ministry of Science and Higher Education of Russia Federation under the grand No. FZGU-2020-0036 .In part of diagnostics of the structures the work of P.V. Seredin was supported by the RF President's Grants Council (Grant MD-42.2019.2).