X-ray Quantitative Phase Analysis Research Articles

Substantial composition and technological treatment of potassium rocks of the Upper Pechora salt basin

The material composition of potassium and potassium-magnesium salts of the Upper Pechora salt-bearing basin was studied, their lithological variability was established over the area of productive strata, depending on the tectonic features of the foundation. The main mining and geological conditions that complicate the possibility of their extraction and the environmental conditions for organizing mining and processing production of mineral salts were established. The basic physical and technological properties of sylvinite and carnallite rocks mined by the mine method were studied for their enrichment by halurgical and flotation methods. The objectives of the work were: determining the material composition, studying textural and structural features and assessing the technological processing of potassium rocks in the Upper Pechora salt-bearing basin. When solving the problems, the following methods were used: a study of the textural and structural features of sylvinites using the petrographic method; the chemical composition of samples and solutions was analyzed by AES spectrometry; the mineral composition of the water-insoluble residue is determined by X-ray quantitative phase analysis.

Study of particles of plasma dynamic synthesis product in the Ti-O system by high-resolution transmission electron microscopy

The paper demonstrates the possibility of obtaining a dispersed product in the Ti-O system by the method of plasma dynamic synthesis. It was revealed that the product consists of two modifications of TiO2: anatase and rutile. The degree of crystallinity is at a level of ~ 98.0%, which indicates the practical absence of an amorphous component. The predominant phase is anatase, which is confirmed by the results of quantitative X-ray phase analysis and high-resolution transmission electron microscopy.

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.

SOLVING MINERALOGY PROBLEMS WITH THE HELP OF THE “ORIGIN" PACKAGE

Algorithms for solving typical mineralogical problems associated with quantitative x-ray spectral analysis and quantitative x-ray phase analysis using the program “Origin” are developed. The calculation of the areas and midpoint of spectral lines using the tabular processor of the program “Origin” is considered. Various approaches to determining the parameters of spectral lines using the least squares method using the standard functions of the program “Origin” were tested. The creation of a user function for approximation of diffraction maxima by the Cauchy function taking into account the doublet character of Ka series of x-rays is also considered. Various built-in algorithms for smoothing functions (based on averaging, polynomial approximation and Fourier analysis – synthesis) were tested to find weak diffraction maxima against strong noise; optimal schemes for the application of these algorithms were found. The considered algorithms can be applied in universities when processing the results of laboratory works on the topics "Analysis of spectra of emission of atoms", "Quantitative x-ray spectral analysis" and "Quantitative x-ray phase analysis".

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 Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

Influence of Current Waveform on the Wear Resistance of Coatings Obtained on VT6 Titanium Alloy with the Electrolytic Plasma Treatment Method

In the study on the “disk–disk” method the wear resistance of coatings deposited on a VT6 alloy by the plasma electrolytic treatment (PET) method in alkaline aqueous solutions containing different concentrations of sodium aluminate (NaAlO2) at various ratios (0–1.4) of cathodic (IC) and anodic (IA) alternating current components while the value of anodic current density was constant (iA = 5 A/dm2), was studied. It was determined that the maximum increase of wear resistance of a titanium alloy surface is provided for the coating fabricated by the following technological condition: an alkaline aqueous solution containing 40 g/L of sodium aluminate NaAlO2; IC/IA = 0.8; and iA = 5 A/dm2. The high wear resistance of coating fabricated by this condition, as it was determined using the quantitative X-ray phase analysis, is caused by a high content of corundum (α-Al2O3) in the coating, which is a part of double-oxide (TiAl2O5) and its low porosity.

Evaluation of Volume Fraction of Austenite in Austempering Process of Austempered Ductile Iron

In the present work, an evaluation of the volume fraction of austenite in austempered ductile iron (ADI) is presented by means of three different methods. Experimental tests were conducted on ADI samples after different austempering conditions and contained different volume fractions of the phase components in the metallic matrix (ferrite plates + austenite). A comparison of the volume fraction of austenite was carried out by metallographic magnetic methods using a variable field, as well as X-ray quantitative phase analysis. The main purpose of this work is to show the effectiveness of the proposed magnetic method for estimating the volume fraction of austenite in ADI cast iron. It is evident that the new method in which variable magnetic fields are used to quantify the phase composition exhibits very high accuracy within the second stage of the austempering transformation, in which the metallic matrix consists of ferrite plates and high-carbon austenite. Finally, this research shows that within the first and third stages the estimation of the volume fraction of the austenite is hampered by errors resulting from the presence of martensite (first stage) and carbide phases (third stage).

Volumetric Reduction of the FeCl2–CaCl2 Melt by Calcium Dissolved in Calcium Chloride

The purpose of this study is to fabricate highly dispersed powder suitable for spheroidization with further application in additive technologies. The volumetric reduction of the FeCl2–CaCl2 melt by calcium dissolved in CaCl2 produced a fine iron powder. The process included three states, notably, the preparation of melts containing FeCl2 and Ca, their mixing, and high-temperature aging at 800°C for 1 h. Upon finishing the process, the solidified fusion cake is divided into top and bottom parts. The product from the top part has a specific surface of 7.60 m2/g, and that from the bottom part has a specific surface of 5.38 m2/g. The average particle size is 157 μm for the former and 124 μm for the latter. Ultrasonic dispersing is reduced to 26 μm and 71 μm, respectively. Quantitative X-ray phase analysis shows that the main phase of powder is metallic iron (more than 97 wt %). Thus, the originality of the research is due to the application of an intense volumetric reduction of iron from chloride melts by calcium dissolved in its chloride. The uniqueness of the study is due to its product, so far as the main part of reduced iron is arranged in the melt bulk in the form of linear aggregates 40–600 μm in length and 10–50 μm in diameter, which easily destruct by ultrasonic dispersal into separate crystals with an average size of 26 μm. The results of the study show the possibility of implementing the calcium-thermal production of fine iron powder.

Synthesis, structural and optical analysis of surfactant assisted ZnO–NiO nanocomposites prepared by homogeneous precipitation method

Abstract The homogeneous precipitation method was used to synthesis ZnO, NiO nanoparticles and ZnO–NiO nanocomposites with and without surfactants, sodium dodecyl sulphate (SDS) and hexamethylenetetramine (HMT) to alter the composition of nanocomposites. The grown samples were annealed at 300 °C and 600 °C for 2 h to convert the hydroxides into their oxides. To investigate the effect of different composition on the crystal growth, particle size, morphology, structural and optical properties of nanocomposite, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy (UV), Raman spectroscopy and Scanning electron microscopy (SEM) were employed. X-ray quantitative phase analysis was used to estimate the volume fractions of ZnO and NiO phases in grown nanocomposites. The percentage of ZnO phase is more than NiO phase in all nanocomposites and strongly depends on composition. The structural parameters like lattice constants (a, c), bond-length (l), unit cell volume (v), density (ρ), d-spacing (d), strain (e) and dislocation density (δ) of ZnO, NiO and ZnO–NiO nanocomposites were calculated. The Scherrer, Williamson-Hall and Size-Strain analysis were used to calculate the crystallite size and lattice strain. The optical parameters such as optical absorption coefficient (α), bandgap (Eg), skin depth (δ), optical density (Dopt), extinction coefficient (k), refractive index (n), optical conductivity (σopt) and dielectric constants (er, ei) were studied from UV–vis spectra. The nanocomposites grown in this study provide an opportunity of band tuning for better functional performance for device fabrication compared to the basic metal oxides. FTIR characteristic peaks and Raman fundamental optical phonon modes confirmed the formation of ZnO, NiO and ZnO–NiO nanocomposites. SEM analysis revealed that ZnO–NiO nanocomposites have different surface morphology by adding different surfactants.

Application of Evolutionary Rietveld Method Based XRD Phase Analysis and a Self-Configuring Genetic Algorithm to the Inspection of Electrolyte Composition in Aluminum Electrolysis Baths

The technological inspection of the electrolyte composition in aluminum production is performed using calibration X-ray quantitative phase analysis (QPA). For this purpose, the use of QPA by the Rietveld method, which does not require the creation of multiphase reference samples and is able to take into account the actual structure of the phases in the samples, could be promising. However, its limitations are in its low automation and in the problem of setting the correct initial values of profile and structural parameters. A possible solution to this problem is the application of the genetic algorithm we proposed earlier for finding suitable initial parameter values individually for each sample. However, the genetic algorithm also needs tuning. A self-configuring genetic algorithm that does not require tuning and provides a fully automatic analysis of the electrolyte composition by the Rietveld method was proposed, and successful testing results were presented.

FeCl2–CaCl2 melt volumetric reduction by calcium dissolved in calcium chloride

The purpose of this study is to obtain highly dispersed powder suitable for spheroidization for further application in additive technologies. Volumetric reduction of the FeCl2–CaCl2melt by calcium dissolved in CaCl2produced fine iron powder. The process consisted of three stages: preparation of melts containing FeCl2and Ca, their mixing and high-temperature aging at 800 °C for 1 hour. At the end of the process the frozen melt was divided into upper and bottom parts. The product from the upper part had a specific surface area of 7,60 m2/g, and for the lower part it was 5,38 m2/g, Average particle size was 157 μm for the former and 124 μm for the latter. After ultrasonic dispersion, it was reduced to 26 μm and 71 μm, respectively. Quantitative X-ray phase analysis showed that the main phase of powder is metallic iron (more than 97 wt.%). Therefore, research originality is the use of volumetric, intensive reduction of iron from chloride melts by calcium dissolved in its chloride. The uniqueness of the study consists in the product obtained, i.e. the main part of reduced iron is in the melt volume as linear aggregates 40 to 600 μm in length, 10 to 50 μm in diameter that are easily broken by ultrasonic dispersion into individual crystals with an average size of 26 μm. The results of the study demonstrated the feasibility of calcium-thermal production of fine iron powder.

The effect of ergocalciferol on the precipitation of calcium carbonate

We have conducted the first study on the effect of ergocalciferol (vitamin D2) on the polymorphism of calcium carbonate. CaCO3 particles are synthesised from aqueous solutions of sodium carbonate and calcium chloride, in the presence of vitamin D2 with different concentrations, at temperatures ranging from 25 to 80 °C. The effect of the additive on the polymorphism and the morphology of the CaCO3 crystallites are characterised using X-ray quantitative phase analysis, scanning electron microcopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Our results show that the presence of vitamin D2 has an impact on the morphology and composition of the CaCO3 crystallites. Vitamin D2 was demonstrated to promote the formation of aragonite à 50 °C with a volume fraction that can reach 83%. Such effect can be attributed to the formation of D2-Ca+2 ion solution complexes and their adsorption on the surfaces of the CaCO3 crystallites.

Interlaboratory comparison tests in mineralogical works

Introduction. Activities of FSBI “VIMS” are aimed at ensuring accuracy and comparability of the results of mineralogical analyses accompanying exploration and technological work. Evaluation of the research result quality is carried out with the help of various metrological instruments, one of which is an interlaboratory comparison test. Purpose. The purpose of interlaboratory comparison tests (ICTs) is to assess the results of X-ray quantitative phase analysis of an artificial mixture of minerals and to confirm the level of competence of testing laboratories. Methods. The procedure for conducting interlaboratory comparison tests is as follows: development of the programme and its approval; collecting and registering applications from laboratories, willing to participate in the ICT programme; preparation and simultaneous sending of control samples with accompanying information materials to those participating in the experiment; statistical processing of obtained results; drawing up, approval and circulation of documents confirming participation of the laboratories. The control sample is a homogenized artificial mixture of minerals (quartz, kaolinite, calcite and pyrite). The accuracy (quality) control of test results was carried out by X-ray quantitative phase analysis. Results . The ICT results showed a high level of competence of testing laboratories. For unreliable and unsatisfactory results percentages total less than 11%, the percentage for unfulfilled results is equal to zero. Interlaboratory comparison tests in mineralogical works are an important means for controlling competence of testing laboratories.

The Influence of Technological Parameters of the Casting Process on the Structure and Selected Properties of Iron-Based Metallic Glasses

The main aim of this paper was to produce amorphous ribbons with specified composition with the use of various process parameters and X-ray qualitative and quantitative phase analysis after casting and heat treating. Station for ultra-fast cooling of the molten alloy with high vacuum pumps designed for the production of metallic glasses in the form of ribbons with the use of Buhler Melt Spinner SC was used. The X-ray qualitative and quantitative phase analysis, microscopic observation, microhardness and thermal properties tests of the investigated ribbons were conducted. Based on experimental data the discussion on the correlation between casting process parameters, phase and quantitative composition and heat treatment was carried out.

Phase composition and morphological analysis of human gallstones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis

Abstract Quantitative phase composition and morphological characterization of 12 human gallbladder stones (GS1–GS12) retrieved from patients of eastern India have been carried out using IR-spectroscopy, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The FTIR spectra indicated that the primary composition of gallstones studied was cholesterol. X-ray powder diffraction study revealed cholesterol monohydrate (CHM) as the major crystalline phase in GS1–GS12. The Rietveld analysis showed that nine of the gallstones were composed exclusively of CHM, while the remaining three stones contained in addition to CHM, small amounts (4.2–10.6 wt%) of calcium carbonate as aragonite and vaterite. The crystallite size of CHM in GS1–GS12 varied between 82(6) and 249(3) nm. The SEM images of gallstones showed different crystal habits of CHM such as plates, thin rods, rectangular and hexagonal blocks, which resulted into different levels of agglomeration at the mesoscopic scale. Presence of numerous parasitic eggs with a typical muskmelon surface in three gallstones (GS2, GS7 and GS9) suggests possible association between the liver fluke infection and biliary stone formation in these patients. To the best of our knowledge, the study constitutes the first report of X-ray quantitative phase analysis of gallstones using the Rietveld methodology.

Quantitative X-Ray Phase Analysis as a Method of Control of Iron Blende Roasting Process

During the process of leaching of roasted ore from fluidized-bed furnace a decrease of zinc (as ZnO) recovery was observed. Within the investigations a comprehensive structural analysis of samples from the process of roasting of zinc concentrates has been made. It has been found that one of the essential causes for zinc recovery decrease is a presence of (Zn,Fe)S sulphide in the ore, instead of pure zinc blende ZnS. Subsequently, (Zn,Fe)S iron blende is oxidized not to ZnO, but to a mixture where the main component is mixed (Zn,Fe)Fe2O4 oxide. Such oxide does not decompose into simple oxides during the process, which leads to a decrease of zinc recovery.

Method of evolutionary structure-sensitive quantitative X-ray phase analysis of multiphase polycrystalline materials

A method of quantitative X-ray phase analysis (QXPA) based on multiobjective evolutionary optimization for automatization and increase in accuracy of QXPA that is based on full-profile analysis by the Rietveld method is proposed. The two-level genetic algorithm performs the probabilistic evolution of profile and structural parameters by the criterion of minimization of the profile R factor and controls their refinement by the method of full-profile difference-differential analysis (a version of the Rietveld method). The method of evolutional QXPA is discussed by an example of a test mixture of minerals that was used in Round Robin on QPA CPD IUCr.

Non-steady state approach to the vacuum nitriding for tools

A method to the control of vacuum nitriding process that could be applicable for a variety of tool steels is presented. The quantitative diffractometric x-ray phase analysis has been applied to identify the nitrides growth and their stoichiometry as the function of steel composition, nitriding parameters and time. It has been found that the nitrogen content in the ɛ nitride depends not only on the nitriding parameters but it is also strongly influenced by alloying elements in steel. This statement has practically excluded using any steady state models to control and monitor the precise nitriding of alloy steels, especially in the case of vacuum nitriding of tool steels. The importance of the nucleation stage for repeatability of vacuum nitriding results has been shown, too. The effective method for active washing of charge is demonstrated and proposed to unify and shorten nucleation time. Finally, the neural network model is presented as a new approach to modelling and control of the non-steady state vacuum nitriding of various tool steels. This model is based on the “boost-diffusion” schedule of the process.