Qualitative X-ray Phase Analysis Research Articles

The Identity and Mineral Composition of Natural, Plant-Derived and Artificial Sweeteners.

The qualitative X-ray phase analysis of natural and artificial food sweeteners was applied to trace the authenticity of such food additives. The mineral composition of different sweeteners commonly added to foods was studied to estimate their mineral profiles and assess the risk related to the toxic elements intake caused by sweetener consumption. The concentration of twenty elements (Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, Ti, V, and Zn) was measured using the inductively coupled plasma-optical emission spectroscopy (ICP-OES) method after the representative samples were wet-digested with a concentrated nitric acid and hydrogen peroxide mixture in a closed-vessel microwave-assisted system. Differences between the mineral compositions of the examined sweeteners were statistically evaluated and discussed. The relationships between the concentrations of the elements determined in the analyzed sweeteners were also investigated. The successful application of the X-ray powder diffraction method proved the identity of all investigated sweeteners; all the analyzed products contained the expected sweetening agent. The results of the quantification of all the elements in the examined sweeteners indicated that these products cannot be considered nutritionally dense. Hence, the presence of toxic elements like Cd, Cr, Ni, and Pb distinctly indicates the need to test such products to guarantee their quality and ensure consumer safety.

Синтез, свойства и применение композитных наночастиц, полученных при окислении водой электровзрывного нанопорошка Al/AlN/Cu

In this work, for the preparation of AlOOH/CuO/Cu composite nanoparticles, nanoparticles based on Al, Cu, their compounds (Cu2Al, Cu9Al4, Cu4Al, CuAl ) And AlN were first obtained and characterized. The regularities of the oxidation of Al/ AlN/Cu nanoparticles in distilled water have been investigated. The optimal parameters for the synthesis of AlOOH/CuO/Cu composite nanoparticles from Al /AlN/Cu nanoparticles have been determined. The morphology of the obtained nanoparticles is shown using electron microscopy. The composition of the precursor and oxidation products was determined by the method of qualitative X-ray phase analysis. The average size of nanoparticles was determined by statistical processing of TEM images of nanoparticles. To construct the diagrams by size, the sizes of at least 1500 nanoparticles were taken into account. The specific surface area was investigated by thermal nitrogen desorption. To determine the optimal synthesis parameters, the oxidation reaction was carried out at different temperatures: 40, 50, 60, 70, 80, 90 °C with an accuracy of maintaining the set temperature of ± 0.1 °C. During the oxidation reaction of Al/AlN/Cu with water, the pH of the reaction mixture was controlled. It was found that the optimum reaction temperature is 60 °C. As a result of the synthesis, porous structures are formed, consisting of nanolobes of fine-crystalline boehmite with a size of 100 – 300 nm and a thickness of 5 – 7 nm, combined into agglomerates, in the center of which copper-based compounds are located. The specific surface area of ​​the reaction products reaches 160 m2/g. The presence of AlN nanoparticles in the composition promotes a more complete conversion of copper and intermetallic compounds with the formation of CuO and Cu2O. It has been shown that the synthesized nanoparticles can be used as an antimicrobial component in the composition of hybrid materials based on polyvinylpyrrolidone and PEG alloy (400 and 20.000).

DESTRUCTION MECHANISMS OF CU-ETP COPPER GUIDES FOR SECTIONAL INSULATORS OF RAILWAY TRACTION

This article presents the results of a research on the operational damage to sectional insulator guides made of hard electrolytic copper Cu-ETP (Electrolytic Tough Pitch Copper). The guides were used on various rail routes, in real conditions, on which the trains ran at maximum speeds between 40 and 120 km/h for periods of 6 or 12 months. The microstructure of the surface, the working layer of the guide, which contacts the graphite plate of the current collector and the cross-section of the guide in the place where it was damaged was examined using the Olympus light microscope. The analysis of the chemical composition in the EDS micro-regions was performed using the Zeiss Supra 53 scanning electron microscope (SEM), while the qualitative X-ray phase analysis was performed with the use of the Panalytical X'Pert diffractometer. Scratches and deformations of the surface layer characteristic of the phenomenon of friction caused by the current collector were observed in the microstructure of the damaged parts of the guides of section insulators. The effect of a very intense oxidation process was also observed, as well as the effects of an electric arc, which according to the author, is the factor that has the most destructive effect on the condition of the guides.

Physical and Chemical Fundamentals of Sodium Phosphate Use in Foundry Production

The technology of synthesis of inorganic binder material based on sodium tripolyphosphate Na5P3O10 and orthophosphoric acid has been developed. The sequence of physicochemical transformations in this system, as well as the optimal mass ratio of orthophosphoric acid and sodium tripolyphosphate are established. The research uses methods of quantitative and qualitative X-ray phase analysis, differential thermal analysis, standard methods of testing samples for compressive strength. The ratios of the atomic radii of the cation (Na) and the anion (P2O7), as well as the presence of hydrogen bonds, provide a significant increase in the binding potential compared to other sodium phosphates. It was found that the strengthening of mixtures with 2…8 mass parts including sodium pyrophosphate, the filler of which is quartz-based sand, occurs as intensely as possible when heated to 150°C. A further increase in temperature above 250 °C leads to the conversion of sodium pyrophosphate to ordinary (non-polymeric) metaphosphate NaPO3, which exists without changes in chemical structure up to 1000°C. The developed binder material, given the global trends of decarbonization and resource conservation, is a competitive alternative to widely used synthetic resins and other organic materials. It does not contain harmful substances and does not emit dangerous products when heated.

Cement Composition Materials Based on Electrochemically and Electromagnetic-activated Filling Water

A technology is proposed for producing electrochemically and electromagnetically activated water and, from the standpoint of resource saving, high-quality cement composite materials. The results of the physicochemical analysis and morphology of the sediment of naturally non-mineralized water activated by different regimes are presented. A quantitative and qualitative X-ray phase analysis, as well as the results of the study of the microstructure of cement stone samples based on mixing water activated in different modes, are given. The strength indicators of cement stone, mortar and concrete samples were established, and the results of a study of the water resistance of cement composites made with the use of activated mixing water were presented. It has been established that electrochemical and electromagnetic activation of mixing water contributes to a change in its physicochemical properties, influences the structure-forming factors of the cement stone and contributes to the improvement of the strength and performance indicators of cement composite materials.

Кристаллическая структура и диэлектрические свойства керамических материалов на основе AgNbO3

Using the data of qualitative X-ray phase analysis, it was shown that in a wide concentration range at 1223 K compounds based on silver niobate are formed in the condition of the heterovalent substitution of tungsten(VI) ions for niobium(V) ions. These compounds are isomorphic to a perovskite-type structure. Microprobe analysis data allows to determine the homogeneity of the analyzed samples and the correspondence of their experimental compositions to the theoretical ones for the formula Ag1-xNb1-xWxO3. Using the data of X-ray diffraction analysis (Rietveld method) in the Crystallography Data Analysis Software – GSAS, the crystal structure of the obtained compounds was refined. The surface morphology of samples having been obtained at 1373 K was investigated by scanning electron microscopy (SEM). It was shown that with an increase of Nb5+ to W6+ substitution degree for Ag1-xNb1-xWxO3 ceramic samples in the range of the (0.2≤x≤0.8) molar ratio, the average particle size for the studied compositions grows from 1.3 to 5.2 μm, respectively. For the obtained ceramic compounds based on silver niobate with a perovskite-like structure (tetragonal distortion), the temperature-frequency dependences of dielectric parameters in the range 300-900 K were studied. It was found that samples slowly cooled from 1373 K are characterized by low values of (ε ~ 10) and loss (tgδ ~ 0.004 at f = 1 kHz) at room temperature. The ceramics obtained are characterized by relatively high values of dielectric permittivity ε at low frequencies and/or high temperatures. The dielectric parameters of the obtained ceramics are similar to the characteristics of so-called "colossal" dielectric constant materials. The revealed features of the dielectric characteristics of quenched ceramics apparently result from Maxwell-Wagner relaxation at intercrystalline contacts.

ВЛИЯНИЕ МИКРОНАПОЛНИТЕЛЕЙ ИЗ ПРИРОДНОГО ВОЛЛАСТОНИТА НА СВОЙСТВА МЕЛКОЗЕРНИСТОГО БЕТОНА

The possibility of obtaining effective highly dispersed additives from natural wollastonite is substantiated and their influence on the properties of fine-grained concrete is investigated. On the basis of wollastonite, a complex micro-filler with particle sizes up to 100 microns was developed, obtained by joint grinding with quartz sand in a 3:1 ratio in a ball mill in the presence of an anionic surfactant naphthalene-formaldehyde type C-3 and a calcium stearate hydrophobizer technical C-17. A suspension of wollastonite with a modal particle diameter of 405 nm was obtained by pre-grinding wollastonite and anionic surfactant in a ball mill, with their further ultrasonic treatment in a bath-type activator. Mathematical models of the dependence of compression and bending strength on the content of the initial components are developed. It is established that the complex microfill leads to an increase in the strength of fine-grained concrete in bending by 2 times, in compression by 1.7 times with its content in the composition of fine-grained concrete in the amount of 10% by weight of cement. Wollastonite suspension increases the bending strength of fine-grained concrete to 3.1 MPa, compression to 57.8 MPa. The results of qualitative x-ray phase analysis showed that the total intensity of diffraction maxima of not fully hydrated alite C3S, belite C2S grains and their aggregates in cement stone with wollastonite decreases by 1.5-2 times compared to the control composition. This is most likely due to the amorphous nature of the wollastonite surface after grinding in a ball mill and ultrasonic dispersion in a bath-type activator. In addition, such particles are the centers of crystallization. Their needle-like shape contributes to the reinforcement of the structure by crystallizing new formations of cement stone.

Estimation of the Range of Variation in the Mineral Composition of Silicate Lake Bottom Sediments Using Data from XRD and XRF

A method is proposed for estimating the range of mineral group content in the cores of silicate bottom sediments of lakes based on the search for the minimum and maximum content of stoichiometric minals that make up the group of minerals, provided that the balance of the mineral composition and the content of elements in the sample is observed. The mineral components were determined using the method of qualitative X-ray phase analysis, the contents of the main rock-forming elements were determined by X-ray fluorescence analysis. Comparison with the results of quantitative X-ray phase analysis showed that the contents of mineral groups either lie in the range calculated in the extreme search procedure based on data on the element composition, or overlap with the calculated range within the measurement error. The systematic discrepancy between the results of calculating the range of content of the silicon dioxide phase and the results of quantitative X-ray phase determination of quartz observed for the samples under consideration is due to the presence of an X-ray amorphous phase of biogenic silica. The proposed method for estimating the range of mineral group content is easy to implement, uses the publicly available MS Excel software, and can be useful for estimating variations in mineral composition by core depth, in conditions of frequent shortages of individual sample material distributed between different methods of analysis

Study of the phase composition of fine-grained tungsten carbide based ceramic materials by x-ray phase analysis

The results of X-ray diffraction analysis of qualitative and quantitative phase composition of powder and solid polycrysral samples of the system a-WC/W 2 C are presented. Powder (nanopowder) samples were obtained by plasmochemical synthesis from tungsten oxide and hydrocarbon. High-density fine-grained structure of ceramics was formed by electropulse plasma sintering (spark plasma sintering) of initial industrial a-WC powders (AlfaAesar). Experimental data were obtained on a Shimadzu XRD-7000 X-ray diffractometer (CuKa, λ = 1.54 A). The optimal modes of X-ray shooting of the ceramic samples based on tungsten carbide are presented. In the absence of reference standards for initial crystalline phases (WC and W2C), quantitative phase analysis was carried out using the reference intensity ratio (RIR) or corundum number (instead of the method of calibration curve). The required quantitative ratios were calculated using the structural parameters of corundum a-Al 2 O 3 and phases a-WC, W 2 C. The results of determining the repeatability of the intensity values were used to select the optimal exposure time and width of the receiving slit of the detector of diffracted X-rays. Study of the effect of the quality of sample preparation on the sensitivity of qualitative X-ray phase analysis showed the feasibility of grinding of the surface of solid ceramic samples and their pre-polishing with a diamond paste (grain size not less than 5/3 pm). The accuracy of quantitative phase analysis of powder and sintered ceramic samples was evaluated. The layer-by-layer phase analysis of the ceramic preform revealed a preferential crystallite orientation (texture) in the surface layer and the absence of the impurity phase W 2 C. The sensitivity of X-ray phase analysis to the content of a-W 2 C phase in nanopowders of tungsten monocarbide has been estimated.

Air Protection of Working Zone against Fine-Dispersed Lithium Compounds Dust by Its Return to the Production Cycle

Based on the analysis of experimental data, it was found that the main source of lithium compounds dust into the environment is the vacuum-drying cabinets and presses used in the technological process at the stage of manufacturing chemosorbents over which forced exhaust ventilation is installed, effectively removing the dust of lithium com-pounds from the air of the working area (up to a value of 0.014 mg/m3 which is 30% less than MPC). We have used the chemical and qualitative X-ray phase analysis methods to determine the chemical composition of dust. It follows from the results obtained that the main components in the dust composition are lithium hydroxide monohydrate and lithium hydroxide – the substances used in technological processes as the main raw material and have a sufficiently high cost. The article analyzes the dispersed composition of dust and its concentration in the air of the working area. It was found that the bulk of the dust particles are much larger than 10 microns, and the dust concentration of lithium compounds is not more than 4.6–6.0 mg/m3 throughout the process. Several systems of air purification from lithium compounds dust are considered. Based on the analysis of the results obtained, the purification system consisting of a battery cyclone and subsequent air flow bubbling through the water layer is proposed. The system allows us to reduce the dust concentration to a value of 0.017 mg/m3 which is 15% less than the MPC for hydroxide and lithium peroxide. It is shown experimentally that the dust of lithium compounds obtained as a result of removal from the air of the working zone can be used in the technological cycle of synthesis of lithium peroxide providing the possibility of obtaining a final product with a content of the base material up to 93.3% by weight. This scheme of removal of lithium compounds dust and its subsequent return to the production cycle can be used in the development of initial data for the design of environmentally friendly lithium peroxide production technology.

Фазообразование, структура и ионная проводимость антимонат-молибдатов серебра

Silver antimonate-based compounds, formed at partial substitution of ions of quinquevalent antimony with ions of hexavalent molybdenum, have been synthesized using the method of solid-phase reaction. Specificities of phase formation processes of mixtures with various mole ratios of the initial components of a system containing silver nitrate and oxides of trivalent antimony and hexavalent molybdenum have been studied in a wide temperature range from 300 to 1023 K. Using the thermogravimetric analysis data, optimal temperatures for synthesis of powders have been determined. Using the method of qualitative X-ray phase analysis together with the method of high-temperature X-ray diffraction, compositions of reaction products of solid-phase interaction at open air heating have been determined. For the temperature of 1023 K, a homogenous area of formation of a solid solution of silver antimonat-molibdates with the structure of a defective pyrochlore-type within 0,0 ≤ x ≤ 2,0 concentration interval has been determined. In the frameworks of Fd-3m spatial group, a full-profile analysis (the Rietveld method) has been carried out to specify the crystal structure (coordinates of population of ions by crystallographic positions, elementary cell parameters), and interrelation in compositions of the obtained pyrochlore phases with their structural disorder and ion-conducting properties has been determined. Ceramic properties (relative density and average size of particles) of the samples sintered at the temperature of 1373 K have been studied.

ОПРЕДЕЛЕНИЕ ЦЕЛЕСООБРАЗНОСТИ ГРАВИТАЦИОННОГО ОБОГАЩЕНИЯ РУДЫ МЕСТОРОЖДЕНИЯ «ДЖАМГЫР»

PURPOSE. The paper studies the material composition of the ore from the Jamgyr deposit located in the Chatkal region of the Jalal-Abad district of the Kyrgyz Republic and determines the expediency of its gravity concentration. The ore belongs to the quartz low sulfide type. Its main valuable component is gold, the content of which averages 8.5 g/t. METHODS. Complex mineralogical analysis was performed using X-ray phase, optical and microscopic analyzes. Sulphide minerals and gold were studied using the method of selective dissolution of natural minerals. X-ray phase analysis was carried out on a portable X-ray diffractometer D2 PHASER (CuKa) of Bruker AXS design in the range of 20 angles from 5 to 80°. The obtained diffractograms were processed in the DIFFRAC.EVA program. A qualitative X-ray phase analysis was performed via comparison of standards (ICDD PDF-2) and diffractograms. A semiquantitative analysis of the sample was carried out using the DIFFRAC.TOPAS program according to Rietveld method. The content of gold was determined on the atomic absorption multielement spectrometer AGEP-0,1 by the assay atomic absorption analysis. RESULTS AND THEIR DISCUSSION. Having studied the morphology of particles of free gold, we have found that the shape of coarse gold is mainly dendritic, small-size gold has the shape of a drop in pyrite. The data on the granulometric distribution of gold show that the percentage of coarse gold is about 70%. The phase analysis data show that the percentage of free gold is 64.37%. The ore study has allowed to substantiate the use of gravity concentration through the GRG test at a hydraulic pressure of 25-12 kPa, ore feed rates from 1000 g/min to 400 g/min, stage-by-stage reduction in size from 100% of 85 μm to 80% of 75 μm. The technique of performing the stage-by-stage gravity concentration conducted in three stages on Knelson concentrator is given and the GRG test determination diagram is presented. The results of each stage and the total result of the GRG test are provided. According to the GRG test result 19.86% of free gold is extracted at the first stage, 35.83% - at the second stage, and 17.65% - at the third stage. The total recovery is 73.34%. CONCLUSIONS. The morphology and release of gold on the concentrates obtained by gravitation on a centrifugal separator are studied. The degree of gold release is determined as well as the gold grain size in I, II, III stage concentrates and relative amounts of free gold grains. The final determination is given to the main shape of gold grains: it is either dendritic or flake. It is also noted that stage-by-stage decrease in the grind size causes changes in the gold grain shape: the particles of isometric forms are expanded into flat grains.

Thermal evolution of Fe - ZrO2 nanocomposite: Insights from calorimetric and microscopy investigations

This article presents the results of an experimental study on the evolution of phases during annealing of ball milled Fe – ZrO2 nanocomposite powder using Differential Scanning Calorimetry, X-ray Diffraction and Electron Microscopy techniques. The formation of FeO phase from Fe and Fe3O4 is identified through Differential Scanning Calorimetry and confirmed using Synchrotron Diffraction and Transmission Electron Microscopy. Qualitative X-ray phase analysis showed the stoichiometry of the FeO phase as Fe0.87O. This phase is expected to be beneficial as it offers strengthening in the Fe matrix and is thermally stable. The activation energy of formation of the Fe0.87O phase was estimated to be ~195kJmol−1. This phase is also found to be partially stabilizing the cubic phase of ZrO2, at high temperatures. A cubic⇆tetragonal transformation of ZrO2 was identified at 1140K. A rather broad peak was observed for Fe α→γ transformation in the Calorimetry thermograms as the Fe grains were nanocrystalline which became sharper as the crystallites grew in size.

Microstructure of Archaeological 17th Century Cast Copper Alloys

Abstract In Poland, researchers have a very strong interest in archaeometallurgy, which, as presented in classical works, focuses on dating artefacts from the prehistoric and early medieval periods in the form of cast iron and copper castings. This study, extending the current knowledge, presents the results of a microstructure investigation into the findings from the Modern era dating back to the late Middle Ages. The investigated material was an object in the form of a heavy solid copper block weighing several kilograms that was excavated by a team of Polish archaeologists working under the direction of Ms Iwona Młodkowska-Przepiórowska during works on the marketplace in the city of Czestochowa during the summer of 2009. Pre-dating of the material indicates the period of the seventeenth century AD. The solid copper block was delivered in the form of a part shaped like a bell, named later in this work as a “kettlebell”. To determine the microstructure, the structural components, chemical composition, and homogeneity, as well as additives and impurities, investigations were carried out using light microscopy, scanning electron microscopy including analysis of the chemical composition performed in micro-areas, and qualitative X-ray phase analysis in order to investigate the phase composition. Interpretation of the analytical results of the material’s microstructure will also help modify and/or develop new methodological assumptions to investigate further archaeometallurgical exhibits, throwing new light on and expanding the area of knowledge of the use and processing of seventeenth-century metallic materials.

Analysis of phase composition of materials synthesized in carbon and tungsten trioxide pyrolysis in a DC electric arc in helium medium

The paper presents phase analysis of materials synthesized as a result of composite electrode (WO3-C) pyrolysis in a dc electric arc in helium medium. Qualitative x-ray phase analysis is performed. Radiograms of crystal lattices of nanoparticles present in the materials were obtained using high-resolution transmission electron microscopy. Nanocrystals were identified by crystal lattice images. Statistical analysis of phase compositions of the materials is carried out. Mean values and variances of the relative content of nanocrystals of different chemical and phase compounds in crystal structures of the synthesized materials are determined.

Thermal analysis of lithium peroxide prepared by various methods

Behavior of lithium peroxide samples at heating in air was studied by the methods of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). In the temperature range from 32 to 82°C all the studied samples we found to react with water vapor forming lithium peroxide monohydrate as confirmed by the methods of chemical analysis and of qualitative X-ray phase analysis. It was found experimentally that in the temperature range from 340 to 348°C lithium peroxide began to decompose into lithium oxide and oxygen, the starting temperature depended on the method of preparation of lithium peroxide. For all the studied samples polymorphism in the temperature range from 25 to 340°C was not detected.

Surface modification of hot work tool steel by high-power diode laser

Laser surface modification, although for a number of years, is a technology, which is still in its infancy. This paper presents the results of laser alloying influence on structure and properties of the surface of the X38CrMoV5-3 hot work steel, carried out using the high-power diode laser (HPDL). Niobium carbide powder was used for alloying. In the paper, investigation results are presented of the melting and alloying of ceramic particles on the surface layer. Results of the metallographic examinations qualitative X-ray phase analysis and the mechanical properties are presented.

Effect of Temperature on the Phase Composition of Surface Layers of Vt1-0 Alloy in the Process of Carburization from Graphite in Argon

By using qualitative X-ray phase analysis, X-ray spectral microanalysis, and microstructural analysis, we studied the evolution of the phase composition of surface layers of VT1-0 titanium alloy in the process of carburization from graphite in an argon atmosphere under 100 kPa pressure in the temperature range 750–1100°C for 5 h. We established that the amount of titanium oxides in the surface layers decreases (up to complete disappearance) and the formation of carbides becomes more intense as the saturation temperature increases and the partial pressure of oxygen in the saturating environment decreases.

Qualitative X-Ray Phase Analysis on the Basis of the Calculated Standards

Qualitative X-Ray Phase Analysis on the Basis of the Calculated Standards

Qualitative X-Ray Phase Analysis of Lignite Gasification Ash. Illustration of a Strategy for Analysis of Very Complex Solids

AbstractA strategy for qualitative X-ray phase analysis of complex multiphase solids is illustrated through the analysis of eight fixed-bed gasification ashes. Coal from the same lignite formation was gasified in three different reactors. Despite the differences in gasifiers and their operating conditions, all of the ash specimens had the same basic crystalline phase assemblage: silicates and aluminosilicates (merwinite, dicalcium silicates, melilite, nepheline, carnegieite and a sodalite structure phase), oxides (ferrite spinels, hematite and periclase), calcite and residual lignite minerals (quartz, plagioclase). The identification strategy relied on a bulk chemical analysis of each ash and used manual methods with the JCPDS-ICDD search manuals for the Powder Diffraction File. Grain picking, size separations, magnetic enrichment, separation by hardness, dissolution of water soluble phases, and further crystallization of the ash through heat treatment all figured in the identification strategy. Identification of more than a dozen minor and trace phases resulted from these additional methods. Several trials with an automated search/match system demonstrated the difficulties of analyses of such complex phase assemblages. The need for SEM characterization of the ashes to accompany the XRD analyses is discussed.