Electron Probe X-ray Microanalysis Research Articles

Distributions of Ag, Bi, and Sb as Minor Elements between Iron-Silicate Slag and Copper in Equilibrium with Tridymite in the Cu-Fe-O-Si System at T = 1250 °C and 1300 °C (1523 K and 1573 K)

New experimental data on the distributions of silver (Ag), bismuth (Bi), and antimony (Sb) between liquid iron-silicate slag and liquid copper metal in equilibrium with tridymite in the Cu-Fe-O-Si system at T = 1250 °C and 1300 °C (1523 K and 1573 K) have been obtained. The experimental methodology involved high-temperature equilibration, rapid quenching of the equilibrated phases, followed by direct measurement of the equilibrium phases with electron probe X-ray microanalysis (EPMA) for measurement of major element concentrations and laser ablation inductively coupled plasma mass spectrometry (LAICPMS) for the measurement of minor element concentrations. The 4-point test approach was employed to confirm the achievement of chemical equilibrium in the current study. Open-system equilibration on quartz substrates in controlled gas atmospheres (CO/CO2/Ar) and closed-system equilibration in sealed quartz ampoules were used. The new experimental data resolve significant discrepancies found in previous studies and can be used as input for the development of thermodynamic databases for copper-making processes.

The sum of component concentrations as a quality indicator in X-ray electron probe microanalysis of minerals

X-ray electron probe microanalysis is a complete mineral analysis technique. Therefore, the sum of obtained concentrations can be used as an indicator of the quality of analysis. There are two kinds of errors of the sum of concentrations. The first is related to the deviation of the sum from the basic value and can be called a difference error. The second is the scattering of results around the mean value and can be called an averaging error. The difference error characterizes the reproducibility of the measurements and equals 0.41% at the current precision level. The averaging error characterizes the repeatability of the measurements and equals 0.23%. The difference error can be used as a quality indicator directly during analysis, while the averaging error can be used after analysis of a batch of specimens. According to the modified three-sigma rule, the acceptable sum values of separate analyses are in the range 98.8-100.8%. This range is obviously valid only for an ideal model with a basic sum value of 100%. In real analyses, the basic value deviates from 100% because of the presence of elements which are not detected in the analysis and elements with a variable valence. According to the three-sigma rule, the acceptable scattering of the sum of concentrations around the average value is ±0.7%.

Elemental analysis of limestone by laser-induced breakdown spectroscopy, scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and electron probe microanalysis

Limestone, a sedimentary rock-forming mineral is a source of lime and is important industrially as it usually contains +95% calcium carbonate and <5% impurities. The presence of these impurities can cause problems while accessing the different applications of limestone requiring high chemical purity. Due to its great significance and multiple applications, the qualitative and quantitative analysis of limestone is highly desirable. The analysis of the emission spectrum obtained at the fundamental harmonic (1064 nm) of Q-switched Nd:YAG laser revealed the presence of Ca, Si, Al, Mg, Na, Fe, Ti, K, Sr and S with varying intensities. The Boltzmann plot method used to deduce the excitation temperature, and the electron number density value measured by the Stark broadening method resulted in the ranges from 4091–4231 K and (1.2–6.4) × 1016 cm−3, respectively. The quantitative analysis has been performed using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique based on the assumption of local thermodynamic equilibrium and optically thin plasma. The results of the CF-LIBS technique were compared to the measurements of other more standard analytical methods such as scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and electron probe microanalysis with good agreement.

On the incorporation of iron into hexagonal barium titanate: I. electron paramagnetic resonance (EPR) study

Electron paramagnetic resonance (EPR) investigations of BaTiO3 + 0.04 BaO + x/2 Fe2O3 (0.007 ⩽ x ⩽ 0.05) ceramics and BaTi0.98Fe0.02O3 single crystals were performed to study the incorporation of Fe ions in the hexagonal 6H-BaTiO3 lattice and their defect properties. The samples were characterized by x-ray diffraction and wavelength-dispersive x-ray electron probe microanalysis. EPR spectra were recorded both in X- and Q-bands at room temperature. Angle-dependent single crystal EPR investigations and simulations of the ceramic powder EPR spectra revealed three different centers, which can be attributed to Fe3+ ions incorporated on crystallographically different Ti sites. Only one of them was already known before. Two spectra with axial symmetry belong to isolated Fe3+ ions incorporated at Ti(1) sites (exclusively corner-sharing oxygen octahedra) and Ti(2) sites (face-sharing octahedra). The difference of their spectral parameters arises from the different trigonal distortions of the two types of octahedra. The third spectrum has orthorhombic symmetry and is caused by Fe3+ centers associated with a nearest-neighbor charge-compensating oxygen vacancy. A model for the location of this associate is proposed.

Bone Tissue Repair During Implantation of Titanium Nickelide Mesh: Scanning Electron Microscopy and X-Ray Electron Probe Microanalysis Observation

Purpose of Study: To study reparative osteogenesis and tissue integration characteristics for implanting three-dimensional mesh structures of titanium nickelide into a bone cavitary defect. Material and Methods: The authors modeled cavitary defects of femoral metaphysis experimentally in Wistar rats divided into an experimental group and control one. The study duration was 60 days in total. The methods of radiography, those of light and electron microscopy, X-ray electron probe microanalysis used. Results: Under implantation the defect was filled with cancellous bone the volumetric density of which more than 1,5-fold exceeded control values (р &lt; 0.001). The implant had biocompatibility, osteoconductive and osteoinductive properties, it stopped inflammatory processes. The membrane protective barrier which prevented connective tissue sprouting was formed on the implant surface in the defect periosteal zone. The osteointegrative junction was formed being persisted up to the end of the experiment. Reparative osteogenesis was performed by direct intramembranous and apposition type. Conclusion: The implant of three-dimensional mesh titanium-nickelide structures has marked osteoplastic properties, and it can be successfully used in orthopedic surgery.

Chemical Degradation Mechanisms of Magnesia–Chromite Refractories in the Copper Smelting Furnace

Magnesia–chromite refractory has been extensively used in the copper-making industry. It is necessary to understand the degradation mechanisms of the current refractory to develop new refractories. In the present study, post mortem refractories from a smelting furnace were analyzed and compared with the results of static corrosion tests on magnesia–chromite refractories in the laboratory at high temperatures. The microstructure and phase composition were carefully investigated by electron probe x-ray microanalysis to understand the degradation mechanisms of the magnesia–chromite refractory in copper smelting conditions. The degradation mechanisms between the magnesia–chromite refractory and the copper smelting slag and CuO transformed from matte are discussed based on the analysis of the post mortem refractory samples and laboratory tests. These results will enable optimization of the industrial process and development of new refractories for copper smelting furnaces.

Experimental Investigation of the Mo–Ti–Zr Ternary Phase Diagrams

In this work, the phase diagrams of the Mo–Ti–Zr ternary system were determined by means of X-ray diffraction, optical microscopy, and electron probe microanalysis. Two isothermal sections of the Mo–Ti–Zr ternary system at 900 and 1100 °C were experimentally established. There are three two-phase regions and one three-phase region at both isothermal sections. The existence of the three-phase region (β1 + Laves + β2) at 900 and 1100 °C indicates that the β phase (bcc solid solution) separates into two phases, i.e. Mo, Ti rich solid solution β1 and Ti, Zr rich solid solution β2. No ternary compounds were detected. The maximum solubilities of Ti in the Laves phase were found to be 19.3 at.% at 900 °C and 18.3 at.% at 1100 °C, respectively. The liquidus projection and reaction scheme of the Mo–Ti–Zr system were also presented based on the present experimental work and literature information.

Evolution of cracks within an Al2O3–40 wt%TiO2/NiCoCrAl gradient coating

In this paper, an Al2O3–40 wt%TiO2/NiCoCrAl gradient coating is deposited by atmospheric plasma spraying (APS). The microstructure and element distribution of the coating are studied by scanning electron microscopy (SEM) and electron probe X-ray microanalysis (EPMA). The crack propagation behaviour in the coating under applied and thermal stress is analysed through a three-point bending test and a thermal shock test, respectively. Two rapid propagation processes of the cracks can be found during the three-point bending test, which lead to two peaks in the load-displacement curves of the gradient coating. The gradual change in the composition also has an effect on the crack propagation process within the coating. Non-directional propagation paths of cracks and the formation of oxides can be observed in the gradient region under the effect of thermal stress, which lead to the spallation failure of the coating.

Interfacial reaction between YSZ electrolyte and La0.7Sr0.3VO3 perovskite anode for application

The synthesis and performance of La0.7Sr0.3VO3/YSZ composites are investigated as alternative anodes for the direct utilization of methane (i.e., biogas) in solid oxide fuel cells. In this study, the structural stability between Sr-doped lanthanum vanadate and yttria-stabilized zirconia was investigated by using the powder mixture annealed at various periods of time and temperatures. The chemical reaction between these two materials in the temperature ranging from 1100 to 1400 °C was examined by X-ray diffraction (XRD) and electron probe microanalysis (EPMA) analyses. According to the examination of La0.7Sr0.3VO3/YSZ powder mixture after heat treatment at 1100–1400 °C, no second phase was detected when the La0.7Sr0.3VO3/YSZ powder mixture was heated at 1100 °C. The reaction products of perovskite SrZrO3 were formed when the specimens were heated treatment at over 1200 °C. Owing to the further diffusion of Sr cations from La0.7Sr0.3VO3 toward the reaction layer/YSZ interface via the reaction layer, the reaction layer was extended into the YSZ. The interfacial reaction behavior between electrode and electrolyte pellets of the reaction couple was examined by EPMA. No reaction products were observed as La0.7Sr0.3VO3/YSZ composite co-fired at 1100 °C. The reaction products of perovskite SrZrO3 were formed when the specimens were heat treated at over 1200 °C. The bonding energy between La-O (188 kcal/mol) is stronger than Sr-O (83.6 kcal/mol). Thus, Sr ions tend to migrate and react with YSZ much faster than La ions. Furthermore, when the Sr concentration increases to 70%, excess of SrZrO3 formation leads to the phase decomposition of perovskite La0.3Sr0.7VO3.

Phase Equilibria of the Co-Mo-Zr Ternary System at 1000 °C

The isothermal section of the Co-Mo-Zr ternary system at 1000 °C was investigated by using 29 alloys. The annealed alloys were examined by means of x-ray diffraction, optical microscopy, and electron probe microanalysis. It was confirmed that three ternary phases, λ1 (Co0.5-1.5Mo1.5-0.5Zr, hP12-MgZn2), ω (CoMoZr4) and κ (CoMo4Zr9, hP28-Hf9Mo4B), exist in the Co-Mo-Zr ternary system at 1000 °C. And the experimental results also indicated that there are sixteen three-phase regions at 1000 °C. Thirteen of them were well determined in the present work: (1) (γCo) + Co11Zr2 + Co23Zr6, (2) (γCo) + Co23Zr6 + e-Co3Mo, (3) Co23Zr6 + e-Co3Mo + μ-Co7Mo6, (4) (Mo) + μ-Co7Mo6 + Co2Zr, (5) (Mo) + Co2Zr + λ1, (6) (Mo) + Mo2Zr + λ1, (7) λ1 + Mo2Zr + CoZr, (8) Co2Zr + CoZr + λ1, (9) Mo2Zr + CoZr2 + ω, (10) κ + Mo2Zr + ω, (11) CoZr2 + liquid + ω, (12) (βZr) + liquid + ω and (13) (βZr) + κ + ω. The homogeneity of λ1 spans in the range of 28.66-50.77 at.% Co and 15.71-37.03 at.% Mo, and that for ω is within the range of 18.66-23.64 at.% Co and 8.53-14.68 at.% Mo. The homogeneity range for κ is from 8.09 at.% to 9.94 at.% Co and 23.13 at.% to 25.58 at.% Mo. The maximum solubility of Zr in μ-Co7Mo6 phase, Mo in Co2Zr phase and Co in Mo2Zr phase were determined to be 6.17, 11.27 and 9.14 at.%, respectively. While the solubility of Zr in e-Co3Mo and (γCo) phases, Mo in Co11Zr2 and CoZr phases were detected to be extremely small. According to this work, the Co23Zr6 phase contained 15.61 at.% Mo and 12.7 at.% Zr. In addition, the maximum solubility of Co and Zr in (Mo) phase and Mo in (γCo) phase were measured to be 3.50, 5.44 and 7.40 at.%, respectively.

Temperature stability of SmCo (2:17) magnets modified by Ni–Cr two-layer coating

The oxidation resistance behavior of SmCo (2:17)-type high-temperature magnets modified with Ni–Cr two-layer coating was studied. The study depicts the mass gain kinetics and magnetic properties of uncoated and Ni–Cr-modified magnets oxidized at high temperature (500 °C) in air for 200 h. The oxidation test results illustrate that the mass gain of uncoated magnet is 6.95 mg·cm−2 which is more than that (0.08 mg·cm−2) of coated magnet after 200 h. For the magnetic properties concerned, there is a great loss for uncoated magnet, while for coated magnet, magnetic properties do not change much. The study of uncoated magnet through X-ray diffraction (XRD) and electron probe microanalysis (EPMA) shows that the invasion of oxygen at high temperature leads to the loss of magnetic properties by changing the microstructure of magnet.

Mineral Grains of Base and Precious Metals in the Surface Layer of Bottom Sediments in the Chukchi Sea

Data on electron microprobe X-ray analysis of mineral grains of base (Cu, Zn, Sn, Pb, Ni, Bi, and Mo) and precious metals (Ag, Au, Pd, and Pt) detected for the first time in the sediments of the Chukchi Sea are presented. The peculiarities of the morphology and chemical composition of the grains are considered along with their sources and distribution in the sediments.

Effect of sodium in brown coal ash transformations and slagging behaviour under gasification conditions

Alkali species in coal play an important role in mineral matter reactions during gasification. Brown coal ashes can be high in sodium (up to 20 wt%), which interacts with other minerals to significantly affect the formation of slag (liquid phase). At high temperatures, sodium in slag affects phase equilibria, liquidus temperature, and slag viscosity. We investigated phase transformations in brown coal ashes at 800–1000 °C and slags at 1200–1600 °C to study the behaviour of sodium species in the range of 3–15 wt% using X-ray powder diffraction, thermogravimetric analysis and electron probe microanalysis. Sodium species appeared in coal ashes in different forms, such as sulfates, carbonates, and alumina-silicates, resulting in different ash bulk compositions. After processing under gasification conditions, alkaline species react with other minerals and may result in the appearance of a liquid phase. In this study, the liquid-phase content of ashes generally increased with increasing sodium concentration. In slags, sodium often decreased the liquidus temperature and solids content below liquidus temperature. It results lower slag viscosity in sodium enriched slags. These findings demonstrate the importance of phase transformations in brown coal mineral matter during gasification, and the potential they have to strongly affect the required operational conditions.

Influence of sulfur on the fate of heavy metals during clinkerization

The fate of heavy metals during clinkerization is of crucial significance to the solid waste utilization, environmental management, and sustainable development. This paper presents a laboratory scale simulation that aims to investigate the effects of sulfur on the fate of Cu, Pb, and Cd during clinkerization. The sulfur-bearing phases (CaSO4·2H2O and CaS) and metal oxides were mixed with cement raw meal in appropriate ratios to produce clinkers. The volatilization and solidification of Cu, Pb and Cd were investigated using atomic absorption spectrometry, thermogravimetric analysis, X-ray diffraction analyses, electron probe X-ray microanalysis, and scanning electron microscopy. The volatilization of Cu slightly increased in the temperature range 950 °C–1450 °C with addition of sulfur. Sulfur promotes the volatilization of Pb and Cd at the temperature from 950 °C to 1250 °C by decreasing the melting point of PbO and CdO. Sulfur increased the solidification ability of clinker decreasing the volatilization ratio of Pb and Cd at the temperature of 1350–1450 °C and 1450 °C, respectively. Both forms of sulfur (CaSO4·2H2O and CaS) have similar effect on the Cu/Pb/Cd volatilization. Sulfur concentrated in interstitial phases of the clinkers mainly as Ca4Al6O12SO4 and CaSO4. Cu, Pb and Cd were mainly solidified within interstitial phases of the clinkers forming solid solutions with the variable compositions. Cu was also present in alite and belite and as crystalline phases of Ca2CuO3 and CaCu2O3 in the clinkers. This research can help to improve understanding of the fate of heavy metals and provide a guideline for risk assessment during the co-processing of solid wastes in cement kiln.

Determination of Precious Metals in Geological Samples from Four Gold Ore Deposits of the North-East of Russia

Compositions of rare mineral phases containing precious metals (PMs) in samples from Natalka, Pavlik, Vetrenskoe, and Degdekan gold ore deposits (North-East of Russia) are studied by scintillation atomic emission spectrometry (SAES) and electron probe microanalysis (scanning electron microscopy and electron probe X-ray microanalysis, SEM–EPMA). The SAES method found dozens and hundreds of particles carrying gold, silver, and all platinum-group elements as native metals, intermetallides and solid solutions, arsenides, antimonites, sulfoarsenides, tellurides, selenides, etc. The variety of the elemental compositions of PM species (mineral phases) found by SAES significantly exceeds the list of minerals found previously by SEM–EPMA because of different natures of optical and X-ray spectra. The sizes of PM particles calculated by the SAES method and measured by SEM–EPMA are similar. The SAES data on the total concentrations of PMs satisfactorily agree with the results of inductively coupled plasma mass spectrometry.

Exploring accurate structure, composition and thermophysical properties of η carbides in 17.90 wt% W-4.15 wt% Cr-1.10 wt% V-0.69 wt% C steel

The heat resistance of the η carbides is important for red hardness and hot strength of high tungsten iron-base alloys. The crystal structure and exact composition of η carbides in this work are revealed to be cubic, Fe3.01W2.33Cr0.38V0.28C1.06 by extraction, X-ray diffraction refinement and electron probe micro-analysis. Defect formation energy calculations show that Cr and V occupy W sites in the lattice. Cr and V decrease the mechanical properties and weaken the elastic heat resistance of η carbides, which is attributed to the CCr and CV bonds weaker than CW bonds and the CCr bonds population decrease at high temperature.

The first case of multiple pulmonary granulomas with amyloid deposition in a dental technician; a rare manifestation as an occupational lung disease

BackgroundOccupational lung diseases, such as pneumoconiosis, are one of the health problems of dental workers that have been receiving increasing interest. Pulmonary amyloidosis is a heterogenous group of diseases, and can be classified into primary (idiopathic) and secondary (associated with various inflammatory diseases, hereditary, or neoplastic). To date, the development of pulmonary amyloidosis in dental workers has not been reported.Case presentationA 58-year-old Japanese female presented with chest discomfort and low-grade fever that has persisted for 2 months. She was a dental technician but did not regularly wear a dust mask in the workplace. Chest X ray and computed tomography revealed multiple well-defined nodules in both lungs and fluorodeoxyglucose (FDG)-positron emission tomography revealed abnormal FDG uptake in the same lesions with a maximal standardized uptake value (SUV [max]) of 5.6. We next performed thoracoscopic partial resection of the lesions in the right upper and middle lobes. The histological examination of the specimens revealed granuloma formation with foreign body-type giant cells and amyloid deposition that was confirmed by Congo red staining and direct fast scarlet (DFS) staining that produce apple-green birefringence under crossed polarized light. Because there were no other causes underlying the pulmonary amyloidosis, we performed electron probe X-ray microanalysis (EPMA) of the specimens and the result showed silica deposition in the lesions. Based on these results, we finally diagnosed the patient with pulmonary granulomas with amyloid deposition caused by chronic silica exposure. Afterward, her symptoms were improved and the disease has not progressed for 2 years since proper measures against additional occupational exposure were implemented.ConclusionsOur case presented three important clinical insights: First, occupational exposure to silica in a dental workplace could be associated with the development of amyloid deposition in lung. Second, EPMA was useful to reveal the etiology of amyloid deposition in the lungs. Last, proper protection against silica is important to prevent further progression of the disease. In conclusion, our case suggested that occupational exposure to silica should be considered when amyloid deposition of unknown etiology is found in the lungs of working or retired adults.

Thorough understanding of the kinetics and mechanism of heavy metal adsorption onto a pyrophyllite mine waste based geopolymer

The present work explored the effectiveness of a geopolymer, synthesized from pyrophyllite mine waste, as an adsorbent for heavy metals such as Co, Cd, Ni, and Pb from aqueous solution. The chemical analysis of mine waste sample revealed the presence of silica (49.38%) and alumina (24.95%) besides Ca and Mg-bearing phases indicating the sample to be a prospective source for the geopolymer formation. The X-ray diffraction studies of the waste sample showed the presence of pyrophyllite, quartz, muscovite with a little amount of anorthite and albite. The presence of these phases was also confirmed by the scanning electron microscopy-energy dispersive X-ray spectroscopy and electron probe microanalysis. The synthesized geopolymerized sample was found to be highly amorphous in nature and did not show any major peaks that were found in the original feed sample. The batch adsorption studies supported the enhanced adsorption capacity of the geopolymer in comparison to the original waste sample. The maximum removal in the range 98–99% of the heavy metals could be accomplished by the geopolymer at pH 7.8, temperature 343 K, and initial metal concentration of 10 ppm. The adsorption data were found to fit pertinently to Langmuir model, Temkin model and pseudosecond order rate kinetics. The mechanism of adsorption was discussed with schematic models.

Interactions of MgO·Al2O3 spinel with Cu, Cu2O and copper matte at high temperature

Magnesia-chrome refractory has been used in the copper industry for decades, and the chromium in the used refractory has been proved to have the risk to harm the environment. A reliable chromium-free refractory is urged to replace the chromium-containing refractory in the future. In the present study, MgO·Al2O3 spinel was systematically tested with Cu, Cu2O, and industrial matte respectively at 1300 °C. All samples were directly quenched into the water after the experiments and examined by electron probe X-ray microanalysis. The molten Cu and MgO·Al2O3 spinel did not react and showed a low wettability, while limited reactions between the spinel and matte were detected. However, severe reactions occurred between the spinel and Cu2O at 1300 °C. The possible applications of the spinel in the copper-making industry are discussed based on the experimental results.

Comparison of selective flocculation of low grade goethitic iron ore fines using natural and synthetic polymers and a graft copolymer

This study aims to beneficiate low grade goethitic iron ore fines using a selective flocculation process. Selective flocculation studies were conducted using different polymers such as starch amylopectin (AP), poly acrylic acid (PAA), and a graft copolymer (AP-g-PAA). The obtained results were analyzed; they indicate the enhancement of the iron ore grade from 58.49% to 67.52% using AP-g-PAA with a recovery of 95.08%. In addition, 64.45% Fe with a recovery of 88.79% was obtained using AP. Similarly, using PAA, the grade increased to 63.46% Fe with a recovery of 82.10%. The findings are also supported by characterizing concentrates using X-ray diffraction (XRD) and electron probe microanalysis (EPMA) techniques.