Phosphate glasses are very promising materials from the application and fundamental point of view. Properties of the glasses are strongly related to the structure which may be modified by various ...glass constituents. In the paper density functional theory calculations of simple phosphate structural units, chains build of them and iron-phosphate clusters are presented. Influence of a position of the unit in the chain is described. Structural changes of the units due to formation of bonds between non-bridging oxygens and iron atoms in different coordinations are shown. The optimized clusters are used then to calculate theoretical Raman and Fourier transform infrared spectra. The calculated spectra are then compared to the experimental results for an iron-phosphate glass from the pyrophosphate stoichiometry region. Finally the structural features of the glass are described.
•DFT simulations of simple structural phosphate units and cluster build of them were conducted.•Theoretical FTIR and Raman spectra of the phosphate and iron-phosphate clusters were obtained.•Influence of iron on phosphate structural units was determined.•Theoretical and experimental FTIR and Raman spectra of 63P2O5 - 37Fe2O3 were compared.•Structural features of the glass were obtained.
Two glasses from CaO-SiO2 binary system were obtained by sol-gel and melting techniques. The effect of two different glass obtaining methods was investigated using X-ray diffraction, FTIR, Raman and ...29Si MAS NMR spectroscopic methods. The measurements revealed significant differences in the glasses structure. Although both glasses were fully amorphous, the gel-derived glass had a more polymerized structure compared to the melt-derived one. The studied glasses were characterized by BET analysis to provide information about specific surface area of the obtained materials. Apart from microstructural evaluation, thermal properties and in vitro bioactivity study of all glasses were conducted to demonstrate differences in performance of the samples. The formation process of hydroxycarbonate apatite (HCA) layer was investigated using inductively coupled plasma mass spectrometry (ICP-MS) and structural studies.
High-performance Li-ion batteries require materials with well-designed and controlled structures on nanometre and micrometre scales. Electrochemical properties can be enhanced by reducing crystallite ...size and by manipulating structure and morphology. Here we show a method for preparing hierarchically structured Li
Ti
O
yielding nano- and microstructure well-suited for use in lithium-ion batteries. Scalable glycothermal synthesis yields well-crystallized primary 4-8 nm nanoparticles, assembled into porous secondary particles. X-ray photoelectron spectroscopy reveals presence of Ti
only; combined with chemical analysis showing lithium deficiency, this suggests oxygen non-stoichiometry. Electron microscopy confirms hierarchical morphology of the obtained material. Extended cycling tests in half cells demonstrates capacity of 170 mAh g
and no sign of capacity fading after 1,000 cycles at 50C rate (charging completed in 72 s). The particular combination of nanostructure, microstructure and non-stoichiometry for the prepared lithium titanate is believed to underlie the observed electrochemical performance of material.
Several different compositions of zinc-containing glasses in the CaO-SiO2 system were obtained by both traditional melting technique and the sol-gel method. The influence of zinc ions addition in the ...glass composition was evaluated using different spectroscopic methods (FTIR and 29Si MAS-NMR). It was demonstrated that ZnO has a significant effect on glass structure and, as a consequence, on thermal properties, texture and bioactivity. EDX and ICP data showed that zinc ions reduce glass bioactivity and incorporate in the newly forming HCA layer. Evaluation of the in vitro biocompatibility of the obtained materials was performed by indirect tests using MG-63 osteoblast-like cells. All samples were found to be biocompatible and zinc ions enhanced the cell viability. Antibacterial tests against gram-negative (E. coli) and gram-positive bacteria (S. aureus) were carried out to evaluate the antibacterial potential of the zinc-doped glasses.
The nanocomposite coatings composed of carbon nanotubes and various forms of copper were prepared in the two-step process. Firstly, carbon nanotubes were coated on stainless steel substrate using ...electrophoretic deposition at constant current. Then, the process of electrochemical deposition using copper(II) sulphate solutions was performed under high overpotential conditions. The modification of the copper(II) cations concentration in the solution and the deposition time provided the formation of various forms of crystals. The samples and their cross-sections were observed and examined using scanning electron microscope equipped with electron dispersive spectroscopy system. The analysis of chemical composition revealed that in addition to the pure copper crystals, the crystals characterized by the presence of copper and oxygen were formed. Therefore, Raman spectroscopy was applied to determine the unknown stoichiometry of this copper oxide. The point and in-depth analysis identified copper(I) oxide in the form of different size crystals depending on the concentration of the copper(II) sulphate solution. To confirm these findings, grazing incidence X-ray diffraction measurements were also performed. the combination of the applied methods has provided the detailed description of the preparation of the nanocomposite coatings with the proposed mechanism of copper(I) oxide formation.
The paper deals with the influence of the microwave treatment on sodium carboxymethyl starch (CMS-Na) applied as a binder for moulding sands. The Fourier transformation infrared spectrometry (FT-IR), ...Raman spectroscopy (FT-Raman) and XRD analysis data of native potato starch and three different carboxymethyl starches (CMS-Na) with various degree of substitution (DS) before and after exposition to microwave radiation have been compared.
FT-IR studies showed that polar groups present in CMS-Na structure take part in the formation of new hydrogen bonds network after water evaporation. However, these changes depend on DS value of the modified starch. The FT-Raman study confirmed that due to the impact on the samples by microwave, the changes of intensity in the characteristic bands associated with the crystalline regions in the sample were noticed. The X-ray diffraction data for microwave treated CMS-Na samples have been compared with the diffractograms of initial materials and analysis of XRD patterns confirmed that microwave-treated samples exhibit completely amorphous structure.
Analysis of structural changes allows to state that the binding of sand grains in moulding sand with CMS-Na polymeric binder consists in the formation of hydrogen bonds networks (physical cross-linking).
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•FT-IR and FT-Raman confirmed structural changes in microwave-treated CMS-Na-based binder.•The DS of CMS-Na is important in the process of formation of the network of intra- and intermolecular hydrogen bonds.•FT-Raman and XRD studies showed that the CMS-Na microwave-treating caused reduction its crystallinity.
Glass, in its various forms, represents one of the largest single outlet for boron products. Boron is a powerful glass component and also confers high chemical resistance for glasses in general. As a ...component it works by reducing melting point, viscosity, thermal expansion coefficient, and increasing transparency and brightness, and even heat resistance of the glass.
Almost every time the use of boron improves fluxing capabilities of a batch, reduces glass batch melting temperature and also reduces the tendency of glass to crystallization.
These specific properties arise from a structural role played by boron in the glass structure. Boron is a network former and is fully integrated to the glass structure in the form of different structural units, in which its coordination can be either three-fold and/or four-fold. Its role and influence on the glass structure is well known. It mainly concerns borosilicate and borophosphate glass, which contains two types of network formers i.e. SiO2 and P2O5.
Due to the lack of literature data about glass additionally containing B2O3 in its composition, the structural features of boron in silicate-borate-phosphate glass are reviewed. The different boron-containing units and spectroscopic techniques (X-ray method, Raman and FTIR spectroscopy) used to identify them are described.
Glasses from a SiO2P2O5K2OCaOMgO system modified by B2O3 addition were analysed. Using spectroscopic methods it was found that the analysed glass samples contained triangular and tetrahedral boron groups along with SiO and PO vibrations. The structural studies indicate the coexistence of BO3 and BO4 structural groups but only in the case of higher content of B2O3 in the glass chemical composition (above 12 mol%). The existence of SiOSi, POP and BOSi vibrations was also confirmed.
In summary, it is concluded that the increasing content of B2O3 in the structure of glass from SiO2B2O3P2O5K2OMgOCaO system results in gradual increase of degree of silicate-borate-phosphate framework polymerization.
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•Glasses from the SiO2-P2O5-K2O-MgO-CaO-B2O3 system were prepared and analysed.•Structural characterization was performed through from MIR and Raman spectroscopies methods.•In the structure of examined glasses, the presence of boron atoms in triangular and tetrahedral coordination was confirmed.•The introduction of B2O3 into the glasses structure results in polymerization of silicate-phosphate network.
The article aims to verify the possibility of obtaining an organic-inorganic material acting as both a binder and a lustrous carbon carrier in bentonite-bonded molding sands. Due to the wide ...industrial application, organoclays can be considered as innovative materials supporting the foundry technology in meeting environmental requirements. In this study, the organic modification of montmorillonite in calcium bentonite (SN) was performed by poly(acrylic acid) (PAA) and its sodium salt (PAA/Na). Additionally, for the purpose of comparison, the sodium-activated bentonite/poly(acrylic acid) (SN-Na/PAA) composites were also prepared. The collective analysis of the research results used in the assessment of the mineral/polymer interaction mechanism indicates surface adsorption combined with the intercalation of PAA monolayer into the mineral interlayer spaces. Materials were characterized by the combination of Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) methods. Based on the XRD analysis, the influence of PAA/Na on the aluminosilicate layered structure was found to be destructive, which may adversely affect the binding properties of SN/PAA/Na composites considered as a potential group of new foundry binders. The SN/PAA and SN-Na/PPA composites (with appropriate polymer content) can act as a binding agent in the synthetic molding sand technology, despite coating the bentonite particles with polymer molecules. The risk of losing the mineral's binding capacity is reduced by the good binding properties of pol(acrylic acid) itself. The article is the first stage (preceding the thermal analysis and the strength tests of molding sands with the prepared organobentonites) in determining the possibility of obtaining a new full-value foundry binder in molding sands with bentonite.
Modified barium gallo-germanate glass hosts are still worthy of attention in studying structure–property relationships. In this work, two different series of glass systems based on ...(60-x)GeO2-xTiO2-30BaO-10Ga2O3 and (60-x)GeO2-xB2O3-30BaO-10Ga2O3 (x = 10, 30, 50 mol%) were synthesized, and their properties were studied using spectroscopic techniques. X-ray diffraction (XRD) patterns revealed that all fabricated glasses were fully amorphous material. The absorption edge shifted toward the longer wavelengths with a gradual substitution of GeO2. The spectroscopic assignments of titanium ions were performed with excitation and emission spectra compared to the additional sample containing an extremely low content of TiO2 (0.005 mol%). On the basis of Raman and FT-IR investigations, it was found that increasing the TiO2 content caused a destructive effect on the GeO4 and GeO6 structural units. The Raman spectra of a sample containing a predominantly TiO2 (50 mol%) proved that the band was located near 650 cm−1, which corresponded to the stretching vibration of Ti-O in TiO6 unit. The deconvoluted IR results showed that the germanate glass network consisted of the coexistence of two BO3 and BO4 structural groups. Based on the experimental investigations, we concluded that the developed materials are a promising candidate for use as novel glass host matrices for doping rare-earth and/or transition metal ions.
This paper presents a study related to the biological degradation of a tricalcium aluminate (C
A) phase treated with reactive media from the agricultural industry. During one month of setting and ...hardening, synthetic C
A was subjected to corrosion in corn silage, pig slurry and chicken manure. The hardening process of the C
A phase in water was used as a reference sample. The phase composition and microstructure of the hydrating tricalcium aluminate slurries were characterised by X-ray diffraction (XRD), thermal analysis (DTA/TG/DTG/EGA), scanning microscopy (SEM, EDS) and infrared spectroscopy (FT-IR). In the samples studied, it was observed that the qualitative and quantitative phase composition of the synthetic tricalcium aluminate preparations changed depending on the corrosion exposure conditions. The main crystalline phases formed by the hydration of the examined samples in water as well as in corrosive media were the catoite (Ca
Al
(OH)
) and hydrocalumite (Ca
Al(OH)
·3H
O) phases. Detailed analysis showed the occurrence of secondary crystallisation in hydrating samples and the phases were mainly calcium carbonates (CaCO
) with different crystallite sizes. In the phase composition of the C
A pastes, varying amounts of aluminium hydroxides (Al(OH)
) were also present. The crystalline phases formed as a result of secondary crystallisation represented biological corrosion products, probably resulting from the reaction of hydrates with secondary products resulting from the metabolic processes of anaerobic bacterial respiration (from living matter) associated with the presence of bacteria in the reaction medium. The results obtained contribute towards the development of fast-acting and bio-corrosion-resistant special cements for use in bioenergetics.
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