Papers by Keyword: IR-Spectroscopy

Abstract: The objective of this research is to study and analyse the properties of a cement-based composite modified with nickel/carbon nanocomposite (Ni/C NC). According to previous studies carried out by scientists in the field of nanostructures, it was assumed that metal/carbon nanostructures can increase the strength and impart electrically conductive properties to composite materials [9,12]. To confirm this hypothesis, in this research, mechanical strength tests and measurements of the electrical resistance of the modified samples were carried out. It was found that the addition of nickel/carbon nanocomposite in the amount of 0.05% increases the compressive strength of silicate composites by 35%. Moreover, by measuring the electrical conductivity of the samples, it was established that with the introduction of additives in the amount of 0.01-0.05% in relation to Portland cement, the resistance decreases by 80-84%. Further, the structural effect of Ni/C NC on the cement matrix was studied by the methods of IR spectral, differential thermal analyses, X-ray microanalysis. As a result of the analysis, it was revealed that the dispersions are crystallization centers during cement hydration and create chemical bonds with silicon oxide in the composition of the silicate composite. Ni/C NC has a structuring effect on the silicate binder matrix through the formation of a denser packing, which affects the mechanical properties and electrical conductivity of the material. The results of the study can be used to obtain electrically conductive materials with desired properties that can perform the functions of heating, monitoring the state of structures during operation, and protecting against an electromagnetic pulse.

Abstract: The oxyhalides Ba₂InO₃F, Ba₂InO₃Cl, and Ba₂InO₃Br were synthesized using the solid state method. It was found that the increasing of halide ion radius leads to the increase of lattice parameters and also caused to redistribution of indium-oxygen bond lengths. The possibility of water uptake was proved by thermogravimetry measurements. The presence of different forms of oxygen-hydrogen groups in the structure of hydrated oxyhalides was indicated by infrared spectroscopy.

Abstract: Joint electrochemical oxidation of copper and aluminum using alternating current (AC) was performed. The electrolysis products were dried on air (method carbonate) and at the residual pressure of 3-5 kPa (oxide method). Cu-Al layered double hydroxide (Cu-Al/LDH) are formed at air carbonization. Oxide method saves copper (I) oxide. Heat treatment causes the decomposition of LDH to CuO and Al₂O₃ as well as Cu₂O oxidation to CuO. Copper-aluminum spinel (CuAl₂O₄) is the product of solid-phase interaction of copper and aluminum oxides. Infrared spectra revealed that oxide method provides the boehmite dehydration and metal oxides interaction at lower temperature despite the fact that the poorly crystallized copper (II) oxide is formed at LDH decomposition.

Abstract: Selective layers Al₂O₃-Ni were prepared by electrochemical way applying anodic oxidation of aluminium and electrolytical colouring. Anodic oxidation of aluminium was realised in sulphuric resp. phosphoric acid and colouring was carried out under periodic reverse current using different colouring electrolytes on nickel basis. The selective layers were studied and analysed with diverse methods before and after exposition to humidity effect. A way of the selective layer preparation is decisive to the final reaction with humidity and so to degradation of the material.

Abstract: This work is devoted to determination of characteristics of hydrogen effusion from SiH bonds in Si rich silicon oxynitride (SRON) films, obtained by plasma enhanced chemical vapor deposition, as a result of thermal anneals at temperatures from 400 to 800°C. The values of the concentrations of SiH bonds in HSi (Si_3nO_n) (0 n 3) complexes contributing to the structure of SRON films are obtained from the analysis of infrared absorption spectra in the range of 2000-2400 cm¹. The kinetics of the decrease of SiH concentrations as a result of anneals is described in the framework of a model with distributed activation energy of hydrogen emission. The median value and the mean-square deviation of this distribution as well as the attempt frequencies of SiH bond breaks are determined from the comparison of experimental and calculated SiH concentrations in SRON films. These characteristics are compatible with such characteristics found for the case of the depassivation of P_bH centers at the Si/SiO₂ interfaces. Obtained results are useful for the controlled formation of the layers of Si nanocrystals in dielectric matrix for Si based tandem solar cells applications.

Abstract: Vibrational spectroscopy has been used to investigate the properties of hydrogen in multicrystalline Si (mc-Si) and its interactions with carbon impurities that can be present with high concentration. The properties of point defects containing N and O have been investigated by way of their vibrational properties and their far-infrared electronic transitions.

Abstract: Magnetite nanopowder is a nanostructured magnetic material which is of great importance due to its electric and magnetic properties at room temperature. There are quite enough methods to produce magnetite. In the present work, four samples of magnetite powder were produced, the first three with the alkaline precipitation method from aqueous solution of mixed Fe (II)/Fe (III) salts, without any surfactants and the last one with the micro emulsion method. The prepared powders have been characterized using transmission electron microscopy, Raman and FT-IR spectroscopy and x-ray diffraction in order the structure and the morphology of magnetite to be examined. The produced magnetite powders have a size range of 10-12±2nm and the chemical composition of magnetite.

Abstract: Mechanochemical activation (MCA) of electrode lignin was performed and the activated lignin was studied by IR-spectroscopy for different activation times. The activated lignin was tested for the ability of binding Cr₂O₇^2-, Cu²⁺, Ni²⁺ ions. It was established that structure deformation, which does not distort the stronger hydrogen bond lattice, but leads to the formation of highly developed surface with active functional groups, occurs in the course of MCA. Weaker inter-layer bonds are broken in the activation process and quickly recovered after the load release. The comparison of the sorption capacity of Cr₂O₇^2-, Cu²⁺, Ni²⁺ ions by the MCA treated vs. inactivated lignin for different activation times was performed.

Abstract: Carbonated apatite, the basic mineral component in human hard tissues and an important bioceramic material, has been extensively studied. However, its atomic arrangements in apatite crystal structure and its experimental characterization are still not lack of debating. We analyzed infrared (IR) vibrational spectroscopy for carbonated apatite determinations, by comparatively studying the IR spectra of hydroxyapatite and of surface carbonate absorption, biological apatites (human enamel, human cortical bone, and two animal bones) and carbonated apatite. The carbonated apatite samples were sythesized by various methods, including precipitation method, hydrothermal reaction and solid-gas reaction at high temperature. The comparative study indicates that the bands at ~880 cm^-1, ~1413 cm^-1, and ~1450 cm^-1 should not be used to identify carbonated apatite since they may result from carbonate absorption on surfaces of apatite crystals or separated carbonate phase present with apatite crystals. The IR characteristic bands of carbonate substitution in apatites should be: ν₃ at ~1465 cm^-1 for type-B (CO₃ substituting for PO₄) and ν₃ band at ~1546 cm^-1 for type A (CO₃ substituting for OH). These signature IR bands are further confirmed by the ab initio simulations.

Abstract: This paper reports experimental results on the production and annealing of oxygen-vacancy related (VO_n, 1<n<5) and carbon-related (C_iO_i, C_iO_iI, and C_iC_s) defects in Ge-doped Czochralski-grown silicon (Cz-Si) materials containing carbon. The samples were irradiated by 2 MeV fast electrons and the behavior of radiation-produced defects is studied by means of infrared (IR) spectroscopy, monitoring the relevant bands in spectra. Regarding the VO_n family, it was found that the presence of Ge affects the annealing temperature of VO defects as well as their fraction that is converted to VO₂ defects. Both effects are discussed in relation with an impact of Ge on the concentration of self-interstitials that take part in the annealing of VO defects via two reaction paths VO + I → O_i and VO + O_i → VO₂. Furthermore, two bands at 1037 and 1051 cm^-1 are attributed to the VO₅ defect, although three other bands at 762, 967 and 1005 cm^-1 are believed to be associated with V_nO_m clusters containing carbon, most likely having a VO_nC_s structure. Regarding carbon-related complexes, it has been established that the annealing of the 862 cm^-1 band belonging to the C_iO_i defect is accompanied by the emergence of the 1048 cm^-1 band previously assigned to the C_sO_2i center. The evolution of the C_iC_s and the C_iO_iI bands is monitored and the identification of bands at 947, 967 and 1020 cm^-1 making their appearance in IR spectra over the temperature range where C_iC_s and C_iO_iI defects are annealed out is discussed.