Electron Probe Microanalysis Methods Research Articles

Studying the features of complex beryllium-containing silicate phases co-crystallization in zonal samples using the x-ray electron probe microanalysis method

Research subject. Silicate ingots containing four species-forming components Be, Mg, Al, and Si and belonging to the crystallization region of beryllium indialite (with the formula of Mg2BeAl2Si6O18 and a beryl-type structure). Aim. To investigate the fundamental problem of identifying the patterns of matter differentiation and the stable and metastable phase formation in silicate matrices. Methods. The evolution of the phase composition of silicate melts was registered using a temperature gradient method. Results. New data on the features of phase transformations in silicate melts belonging to the region of beryllium indialite were obtained by electron probe microanalysis (EPMA). Co-existing metastable and stable mineral phases were identified, and the similarity of their compositions with different structures was shown. The nature of impurity phases at each stage of crystallization was established. Conclusions. The evolutionary sequence of phase associations ensuring the crystallization of beryllium indialite and metastable phases of a similar composition, the nature of which is determined by the initial ratio of components, was experimentally recorded. The range of possible phase associations that co-crystallize or replace a stable phase with a beryl structure in melts from the region of existence of beryllium indialite in the BeO–MgO–Al2O3–SiO2 system was extended. The selectivity of the coloring element chromium entry into various phases of the studied system is shown depending on the capabilities of their structure. The addition of a chromophore is a reliable criterion for visualizing successive layers, zones, and areas of changing phase associations in the final ingot.

An Experimental Study of an Ion Thruster with Electrodes of an Ion-Extraction System Made of a Fine-Structure Carbon–Carbon Composite

This article presents the results of 1000-h tests of a radiofrequency ion thruster (RFIT) with electrodes of an ion-extraction system made of carbon–carbon composite material based on the non-woven carbon frame. The quality of the surface of the thruster IES accelerating electrode being the key element of the RFIT from the lifetime point of view was assessed by visual examination and scanning electron microscopy. The maximum depth of erosion cavity on the accelerating electrode surface was determined. Electrode-surface elemental analysis was performed by the method of electron-probe microanalysis.

Radioactivity of metallurgical enterprises waste

Abstract. Problem. The problem of obtaining environmentally friendly materials is especially relevant when using the wastes that concentrate natural radionuclides (NRN) dangerous for public health. The concentrators of radionuclides include dump and granular blast-furnace slags. Goal. The purpose of the work is to determine the radionuclide composition of the fractions of dump and granular blast-furnace slags from Ukrainian enterprises, their compliance with the radiation safety standards of Ukraine and international radiological indicators, and to identify the factors that determine the level of natural radioactivity of the slags. Methodology. The specific activity of natural slag radionuclides was determined by the gamma spectrometric method on a SEG-001 scintillation gamma spectrometer. The mineral composition of the crystalline component of the slag was determined using X-ray phase analysis performed on a Siemens D500 powder diffractometer. The elemental composition of blast furnace slag was determined by the method of electron-probe microanalysis on a JSM-6390 LV scanning electron microscope with an INCA micro-X-ray analysis system. The particle charge and electrokinetic potential were determined during macroelectrophoresis of suspensions. Results. The blast-furnace slag contains natural radionuclides: 226Ra, 232Th and 40K. The content of radionuclides varies by waste fractions. According to the contribution to the total activity value, NRN can be arranged in a row: 40К > 226Ra > 232Th. The most radiation-clear is the fraction > 20 mm of the “Zaporizhstal” dump slag, the radioactivity of the fractions 1.25‒2.5 mm for DMC, 5‒10 and 0.63‒1.25 for MMC and the “ArcelorMittal” granulated slag is increased. All investigated slags belong to the first class of radiation hazard (Сef 370 Bq/kg) and can be used in construction without restrictions. Originality. All investigated slags correspond to international radiological indicators: Raeq 370 Bq/kg, radiation hazard indices are Iγ, Iex, Iin and Iα 1, which indicates that there is no danger of increased gamma radiation and emanation of radon and the daughter products of its decay into the room air. The concentration of radon indoors does not exceed 200 Bq/m3. For the average sample and slag fractions <2.5 mm of “ArcelorMittal”, the activity utilization index which determines the safety of practical waste use is overestimated; the absorbed dose rate in the open air and the annual effective equivalent dose are higher than the world average values, they are, respectively, 58 nGy/h and 0.07 mSv, but at the same time below the value recommended by the IAEA for the population of 1 mSv/year. The excess lifetime carcinogenic risk for dispersed fractions of “ArcelorMittal” slag is higher than the world average: 0.29·10–3, but below the 0.05 limit set by the International Commission on Radiation Protection. A direct correlation between the acidity of the slag fractions and the increase in radiological parameters was determined. Practical value. An attempt has been made to relate the radioactivity of blast-furnace slag with the NRN sorption on the negatively charged surface of slag particles, which is more reliable for amorphous sorption-active granular slag.

Analysis of geological glasses by electron probe microanalysis under low beam current density conditions

An electron probe microanalysis method was developed to mitigate alkali ion migration effects under low beam current density conditions with a time-saving mode to collect alkali-ion X-ray signals. The method is suitable for estimating H2O content in H2O-rich geological glasses as a substitute technique for SIMS and FTIR.

Кристаллохимические особенности обогащенного стронцием аквалитоподобного минерала из Кондерского массива

A hydrated Sr-rich member of the eudialyte-group mineral from Konder (Southern Yakutia) alkaline complex has been investigated by the methods of electron probe microanalysis and X-ray diffraction. The crystal structure was refined to R = 3.9 % in the anisotropic approximation of atomic displacements using 2188 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.1039(2), c = 31.0743(4) Å, V = 5353.1 Å3; the space group R3. The chemical composition of the studied mineral (Z = 3): 
 Na3.87K0.06Sr1.01Ba0.16Ca4.65REE0.47Y0.3Fe0.38Mn1.27Zr2.92Hf0.3Ti0.09Nb0.12Mg0.07Si25.83O72Cl0.17. 
 The crystal chemistry features of the mineral and its place among hydrated eudialytes are discussed.

Electron probe microanalysis of the elemental composition of phytoliths from woody bamboo species.

Electron probe microanalysis (EPMA) is promising for accurately determining elemental components in micro-areas of individual phytolith particles, interpreting compositional features and formation mechanisms of phytoliths in plants, identifying archeological and sedimental phytolith. However, the EPMA method of analyzing mounted slide phytoliths has not well been defined. In this study, we attempted different EPMA methods to determine the elemental compositions of phytoliths in mounted slides. Direct analysis of carbon (DAC) with other elements in phytolith could obtain abnormally high total values and carbon values. The method of carbon excluded in measuring elements (non-carbon analysis (NCA)) was feasible to obtain elemental compositions in phytolith. The NCA method was conducive to obtain the factual elemental compositions of an individual phytolith (morphotype) when the carbon content of phytolith was relatively low. The EPMA results of phytoliths from 20 bamboo species (three genera) showed that phytolith was dominantly composed of SiO2 but also included low contents of diverse other elements. The EPMA of phytoliths can provide the elemental composition of micro-areas of an individual phytolith particle. The elemental compositions of phytolith varied with their morphotypes, the genera and ecotype of bamboos. The EPMA of elemental compositions in phytoliths is a potential tool to study the formation mechanism of phytoliths, plant taxonomical identification, archaeological and paleoenvironmental reconstruction.

Effect of high temperature molten salt corrosion on the microstructure of a Co-Mo-Cr-Si wear resistant alloy

The corrosion behavior of a novel low Cr content Laves phase strengthened wear-resistant alloy (Co-27.3Mo-2.9Cr-3.1Si) in molten FLiNaK salt (LiF–NaF–KF: 46.5–11.5–42 mol.%) was investigated by static immersion test at 700 °C. The microstructure and phase composition of the alloy after corrosion were characterized by scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) and transmission electron microscopy with energy dispersive spectrometry (TEM/EDS). Results show that the alloy surface exhibit either pitted or roughened morphology after corrosion. The preferential corrosion of the Laves phase contributes to the pitting, whereas the formation of Co 3 Mo particles and Co layers contributes to the roughening. Carburization occurs in both the Laves phase and alloy matrix in the corrosion affected zone, forming Co 3 Mo 3 C carbides of different sizes. In addition, the thermal exposure effect during corrosion causes phase transformation in the entire alloy matrix and form Co 3 Mo stripes. The observed non-uniform corrosion is mainly induced by the trace amount of H 2 O in the salt, and it suggests that the corrosion resistance of the alloy is not satisfying in the test condition. • A novel low Cr content wear-resistant alloy was fabricated and its corrosion behavior in molten fluoride salt was tested. • Complex changes in microstructure induced by molten salt corrosion were characterized by XRD, SEM, TEM, EDS and EPMA methods. • The non-uniform corrosion of the alloy was mainly induced by the trace amount of water presented in the salt.

First find of a potentially new mineral, Na-dominant at M 2-site eudialyte analogue: crystal structure and significance as a marker of ultraagpaitic environment

A potentially new mineral, M2Na-dominant analogue of eudialyte from the Khibiny alkaline massif, was investigated
 using the methods of electron probe microanalysis, X-ray diffraction, and IR spectroscopy. The crystal structure was refined to
 R = 5.7% in the anisotropic approximation of atomic displacements using 2577 independent reflections with F > 3(F).
 The unit-cell parameters are: a = 14.277(1), c = 30.400(1) Å, V = 5328.7(1) Å3; the space group is R-3m. The idealized formula of the mineral is (Z = 3): Na14Ca6Zr3[Na2(Fe,Mn)][Si26O72](OH)2(H2O1.0Cl0.6S2-0.5)(OH,H2O)2.5. Distribution of cations in the M2 micro-region is established: Fe in the flat-square coordination, Mn in the square pyramid and Na in the seven-vertex polyhedron. A comparative analysis of crystal chemical features of eudialyte М2Na-analogue samples from the Khibiny-Lovozero alkaline complex and Ilimaussaq alkaline pluton, Greenland is given. The mechanism of blocky isomorphism with the replacement of IVFe2+ with VIINa in the M2 micro-region is discussed. IR spectra of the М2Na-dominant eudialyte analogue are given: essentially hydrated sample (Na,H3O,H2O)15Ca6Zr3[Na2Fe][Si26O72](OH)2Cl∙2H2O from Ilimaussaq, less hydrated М2Zr-bearing sample (Na,H3O)13(Ca4Mn2)Zr3(Na2Zr)[Si26O72](OH)2Cl∙H2O from Lovozero and low-hydrated sample Na14Ca6Zr3[Na2(Fe,Mn)][Si26O72](OH)2Cl(OH,H2O)3 from Khibiny studied in this work.

Chemical and physical heterogeneity within native gold: implications for the design of gold particle studies

Studies of populations of gold particles are becoming increasingly common; however, interpretation of compositional data may not be straightforward. Natural gold is rarely homogenous. Alloy heterogeneity is present as microfabrics formed either during primary mineralization or by modification of pre-existing alloys by chemical and physical drivers during subsequent residence in either hypogene or surficial environments. In electron-probe-microanalysis (EPMA)-based studies, the combination of Cu, Hg, and Pd values and mineral inclusion suites may be diagnostic for source style of mineralization, but Ag alone is rarely sufficient. Gold characterization studies by laser-ablation-ICP mass spectrometry linked to both quadrupole and Time-of-Flight (ToF-MS) systems show that only Ag, Cu, and Hg form homogenous alloys with Au sufficiently often to act as generic discriminants. Where present, other elements are commonly distributed highly heterogeneously at the micron or submicron scale, either as mineral inclusions or in highly localized, but low concentrations. Drawing upon our own data derived from individual inspection and analyses of approximately 40,000 gold particles from 526 placer and in situ localities worldwide, we show that adequate characterization of gold from a specific locality normally requires study of a minimum of 150 particles via a two-stage approach comprising spatial characterization of compositional heterogeneity, plus crystallographic orientation mapping, that informs subsequent targeted acquisition of quantitative compositional data by EPMA and/or laser-ablation ICP-MS methods. Such data provide the platform to review current understanding of the genesis of gold particle characteristics, elevating future compositional studies from empirical descriptions to process-focused interpretations.

Кристаллическая структура и индикаторное значение одихинчаита из Хибинского массива

Odikhinchaite, a Sr-Mn-Nb-CO3-dominant eudialyte-group mineral from the Khibiny alkaline complex has been investigated using the methods of electron probe microanalysis, X-ray diffraction, infrared and Mössbauer spectroscopy. The crystal structure was refined to R = 3.4 % in the anisotropic approximation of atomic displacements using 3815 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.2709(1), c = 30.023(1) Å, V = 5295.33(7) Å3; the space group is R3m. The simplified formula of the mineral is (Z = 3): Na11Sr3(Mn2+,Fe2+,Fe3+)Ca6Zr3Nb[Si25O72(OH)](CO3)Cl(OH,O)4. The studied sample is the second find of this rare mineral worldwide, represented by a variety with high Fe content in the M2 micro-region, belonging to the taseqite — odikhinchaite solid-solution series. The significance of odikhinchaite as an indicator of a stage corresponding to maximum Sr activity in specific ultraagpaitic pegmatites is discussed.

Study on the interface of Al/Mg bimetal by static casting

In this study, fine aluminum cladding AZ91 magnesium alloy composite ingot was prepared under static casting. The microstructure and phase constituents of the interface were investigated by optical microscopy. The result shows that the interface from the Al matrix side can be divided into three parts. A diffusion layer made up by β-Al3Mg2, Mg-Al mtermetallic compound layer which is made up by γ-Mg17Al12 and a eutectic structure layer made up by α-Mg and γ-Mg17Al12. The element distribution is investigated by methods of electron probe microanalysis (EPMA). The component ratio of Al to Mg decreases in the whole interface. But the descent becomes very slow in the α-Mg and γ-Mg17Al12 eutectic structure layer. The Vickers hardness in the matrix and interface were also measured. The value of microhardness decrease with the phase changing in the whole interface from 120 HV to 275HV, but it’s still much higher than the Al matrix or AZ91 matrix as well.

Electron microprobe study of turquoise-group solid solutions in the Neyshabour and Meydook mines, northeast and southern Iran

ABSTRACT Turquoise, CuAl6(PO4)4(OH)8·4H2O, belongs to the turquoise group, which consists of turquoise, chalcosiderite, aheylite, faustite, planerite, and UM1981-32-PO:FeH. In order to study turquoise-group solid solutions in samples from the Neyshabour and Meydook mines, 17 samples were selected and investigated using electron probe microanalysis. In addition, their major elements were compared in order to evaluate the feasibility of distinguishing the provenance of Persian turquoises. The electron microprobe data show that the studied samples are not constituted of pure turquoise (or any other pure endmember) and belong, from the chemical point of view, to turquoise-group solid solutions. In a turquoise–planerite–chalcosiderite–unknown mineral quaternary solid solution diagram, the chemical compositions of the analyzed samples lie along the turquoise–planerite line with minor involvement of chalcosiderite and the unknown mineral. Among light blue samples with varying hues and saturations from both studied areas, planerite is more abundant among samples from Meydook compared with samples from Neyshabour. Nevertheless, not all the light blue samples are planerite. This study demonstrates that distinguishing the deposit of origin for isochromatic blue and green turquoises, based on electron probe microanalysis method and constitutive major elements, is not possible.

Na-доминантный в M2-позиции аналог эвдиалита: кристаллическая структура и индикаторное значение

Minerals of the eudialyte group from ultra-agpaitic associations are often characterized by high contents (up to the dominance) of sodium at the M2 site, which is populated with iron in eudialyte. The features of blocky isomorphism with the replacement of IVFe2+ by IVNa and VNa at the M2 micro-region are discussed. Using the methods of electron probe microanalysis, X-ray diffraction and IR spectroscopy, a potentially new mineral, M2Na-dominant analogue of eudialyte from the Ilimaussaq alkaline massif (Greenland), was investigated. Its crystal structure was refined to R = 5.6 % in the anisotropic approximation of atomic displacements using 1095 independent reflections with F > 3(F). The unit-cell parameters are: a = 14.208(1), c = 30.438(1) Å, V = 5321(1) Å3; the space group is R-3m. The idealized formula of the mineral is (Z = 3): (Na,H3O)15Ca6Zr3[Na2Fe][Si26O72](OH)2Cl∙2H2O.

Synergic effects of electrolytic manganese residue-red mud-carbide slag on the road base strength and durability properties

The present study was designed to prepare the road base material by using electrolytic manganese residue (EMR), red mud (RM) and carbide slag (CS) as main raw materials. The mix was optimized and mechanical properties, durability, strength formation mechanism and environmental behavior were investigated. X-ray diffraction (XRD), Mercury intrusion porosimetry (MIP), 29Si and 27Al magic-angle spinning (MAS) nuclear magnetic resonance (NMR) and electron probe microanalysis method (EPMA) were used for microstructure characterization. The results show that after curing for 7 days, the EMR-RM-CS exhibited the highest unconfined compressive strength (UCS), showed the best durability, the best pore diameter distribution and critical pore size. Hydration characteristics reveal that C-A-S-H gel and AFt are generated in EMR-RM-CS, which is positive to the form of UCS and durability. 29Si analysis demonstrates that the synergy of EMR, RM and CS has the best polymerized structure. Al in the hydrated pastes exists in the form of AlIV and AlVI, and one part of the dominant AlIV is activated and another one is converted to AlVI. The leaching results meet the Chinese groundwater standards which indicate that EMR-RM-CS system can well solidify the heavy metals. The road base material prepared by EMR not only consumes a significant quantity of solid wastes but also provides a new idea for the synergistic utilization of solid wastes.

Microstructural peculiarities of aluminides of nickel, titanium, and cobalt

Scanning electron microscopy, electron probe microanalysis, X-rays diffractometry, and microhardness measurements were used for studies of diffusion zones in systems Al-Тi, Al-Co, and Al-Ni formed by means of diffusion couples method in a temperature range of 1,300-1,350 °С. It was shown that diffusion zones have the multilayer structure with numerous peculiarities. For a number of intermetallic compounds formed in all three systems there were revealed their temperature shifts using the electron probe microanalysis methods and confirmed with X-rays diffractometry. The correlation between the individual intermetallic layers and their microhardness numbers are not always evident. For some aluminides the microhardness can reach 7,060 ± 1,200 MPa (in globular area of Ti5Al11 and TiAl) and 4,938 MPa (in multilayer area of titanium aluminide TiAl2). For very thin (about 10 μm) layers in multilayer area the microhardness has been measured in the first time 4,000 MPa (TiAl) and 4,450 MPa (Ti3Al). The obtained microhardness numbers demonstrated reasonable coincidence with previous published results. Microhardness in Al-Ni system was measured as 5,200 ± 500 MPa (for β-NiAl) and 5,300 ± 860 MPa (for γ΄-Ni3Al). For cobalt aluminide СоАl from Аl-Со system the microhardness showed numbers 3,900 ± 200 MPa, whereas for СоАl3 it was higher up to 6,600 MPa. The intermetallic compound γ΄-Ni3Al considered as the most interesting from practical point of view had small (up to 10 μm) width whereas the next layer Ni3Al5 had the wider (100 μm) width. There were also revealed some globular Ti5Al11 having thin shells which consist of intermetallic Ti9Al2.

Investigation of Microstructure, Nanohardness and Corrosion Resistance for Oxi-Nitrocarburized Low Carbon Steel

A role of oxi-nitrocarburizing technique for low-carbon steel was intensively evaluated as a means of reducing the problem of corrosion in gas nitrocarburizing, which is a vital disadvantage of gas nitrocarburizing. Oxi-nitrocarburizing was carried out by a two-step process: Gas nitrocarburizing at 560 °C and oxidation. In order to characterize two different methods of oxi-nitrocarburizing, oxidation was performed under two different conditions: Air and steam as oxygen sources. To analyze the microstructural, physical, and chemical properties of the thin oxide layer and nitride layer, which are the surface hardened layers formed on low-carbon steel by oxi-nitrocarburizing, several methods, such as electron probe microanalysis (EPMA), electron backscattered diffraction (EBSD), scanning electron microscopy (SEM), nanoindentation tests, and potentiodynamic polarization tests were applied. The results indicated that the EPMA and EBSD methods are powerful techniques for the analysis of microstructure, such as phase analysis and metallic element distribution in the oxide layer of magnetite and compound layer of ε-phase and γ′-phase, for oxi-nitrocarburized low-carbon steel. Additionally, the nanohardness using the nanoindentation test and corrosion resistance using the potentiodynamic polarization test for the oxi-nitrocarburized specimens are useful methods to understand the mechanical and corrosion properties of the surface hardened layer.

Investigation into micro-physicochemical interaction between sodium dodecylbenzene sulfonate (SDBS) and partially hydrolyzed polyacrylamide (HPAM) utilizing electron probe microanalysis method

After adding a surfactant to the polymer solution, the interaction between them has a significant influence on the oil recovery of polymer/surfactant (SP) flooding. The study of the micro-physicochemical interaction between sodium dodecylbenzene sulfonate (SDBS) and partially hydrolyzed polyacrylamide (HPAM) can contribute toward an understanding of the action of SP flood. In this paper, the characteristic interaction parameter (CAC and PSP) was determined by tensiometry, the microstructure of HPAM and SP solution was observed with electron probe microscope, then the distribution of SDBS in the mixtures of HPAM and SDBS was determined based on the characteristic of Sulfur. Results show HPAM and SDBS begin to aggregate after the CAC and HPAM is saturated by SDBS above the PSP. HPAM molecules in aqueous solution have a multilayer three-dimensional network structure in the form of aggregates. Most structures are hexahedral, in which there are solid backbones attached with thin branches, the mesh is from 10 μm to 100 μm. Compared with HPAM, the size of the mesh in the sample of SP solution has no noticeable change, but the network layer is reduced, the density of mesh is decreased, the rough skeleton becomes more substantial, and the branch is less. The thin films occasionally scattered in the mixtures of HPAM and SDBS. Approximate 50% of the SDBS in the solution formed aggregates with HPAM molecules by hydrophobic interaction.

Specific Features of Wear of Oil-Scraper Piston Rings with Tin Coatings in Bench Tests for Friction and Wear

We study the process of wear of commercial oil-scraper piston rings of a D100 locomotive diesel generator in a reciprocating friction machine simulating their operating conditions. The degree of wear of these rings is determined by their weight and the increase in the working surface of a ring for different sliding speeds. We also evaluate the changes in their microhardness prior to and after tests. The character of structural changes of the friction surface for different parameters of testing is established by the method of electron-probe microanalysis. It is shown that the run-in tin coating is absent on the leading edges of the rings, where the characteristic friction bands are formed with the appearance of a graphite network of the substrate. A specific feature of structuring of the inclined surface is established in the area, where this surface is adjacent to the working collar. In order to increase the durability of these rings in operation, it is recommended to deposit ion-plasma nanocoatings with additional quality control and guarantee the relaxation of residual stresses.

Decay of Impurity Nano-inclusions of Cobalt in Silicon under the Influence of Thermal Annealing

The influence of a thermoannealing on electrical conduction of silicon monocrystals doped by cobalt has been studied. Also, analysis of sequence of the impurity nanoinclusion’s disinteration under influence of thermoannealing has been carried out by the method of electron-probe microanalysis.

Chemical U–Th–total Pb dating and structural disorder of monazite-(Ce) from granitoids of the Aduiskii massif, Middle Urals

Using the methods of electron probe microanalysis and Raman spectroscopy, the zoning, chemical composition, and disorder in the matrix of accessory monazite extracted from a synplutonic quartz dioritic dyke intruding migmatite, diorite, and fine-granular granite of the Aduiskii massif were studied. It was established that monazite grains contained inner and outer zones. The contributions of chemical and radiation factors to mineral disorder were estimated. The results of chemical U-Th-total Pb dating of mineral are reported. The age 252 ± 4 Ma corresponds to the second maximum of granite formation.