Probe X-ray Microanalysis Research Articles

Physicochemical Properties of Yttria-Stabilized-Zirconia In-Flight Particles during Supersonic Atmospheric Plasma Spray

In order to achieve better knowledge of the thermal barrier coatings (TBCs) by supersonic atmospheric plasma spraying (SAPS) process, an experimental study was carried out to elaborate the physicochemical properties of particles in-flight during the SAPS process. One type of commercially available agglomerated and sintered yttria-stabilized-zirconia (YSZ) powder was injected into the SAPS plasma jet and collected by the shock chilling method. The YSZ particles’ in-flight physicochemical properties during the SAPS process, including melting state, morphology, microstructure, particle size distribution, element composition changes, and phase transformation, have been systematically analyzed. The melting state, morphology, and microstructure of the collected particles were determined by scanning electron microscopy (SEM). The particle size distribution was measured by a laser diffraction particle size analyzer (LDPSA). Element compositions were quantitatively analyzed by an electron probe X-ray microanalyzer (EPMA). Additionally, the X-ray diffraction (XRD) method was used to analyze the phase transformation. The results showed that the original YSZ powder injected into the SAPS plasma jet was quickly heated and melted from the outer layer companied with breakup and collision-coalescence. The outer layer of the collected particles containing roughly hexagonal shaped grains exhibited a surface texture with high sphericity and the inside was dense with a hollow structure. The median particle size had decreased from 45.65 to 42.04 μm. In addition to this, phase transformation took place, and the content of the zirconium (Zr) and yttrium (Y) elements had decreased with the evaporation of ZrO2 and Y2O3.

Complex Phosphates M0.5 + xM′x Zr2 − x(PO4)3 (M = Cd, Sr, Pb; M′ = Ni, Cu; 0 ≤ x ≤ 2) with an-NZP Type Structure

M0.5 + xM′x Zr2 − x(PO4)3 phosphates (M = Cd, Sr, Pb; M′ = Ni, Cu; 0 ≤ x ≤ 2) were synthesized by the sol-gel method with followed by heat treatment. The samples were studied by X-ray diffraction, electron microscopy, microprobe analysis, and IR spectroscopy. The formation of limited solid solutions with an NaZr2(PO4)3 (NZP) structure was established in the studied series. Some tendencies in their crystallographic characteristics depending on the chemical composition were elucidated. The crystal structures of Sr0.9M′0.4Zr1.6(PO4)3 phosphates (M′ = Ni, Cu; space group $$R\bar{3}$$ , Z = 6) were refined using X-ray powder diffraction data by the Rietveld method. The effect of the size factor on the formation of phosphate structures was demonstrated.

Interfacial reactions of 68In–32Bi, 50In–50Bi and 33In–67Bi low melting alloys on Cu substrates

In this study, the interfacial reactions, microstructures, and intermetallic compounds (IMCs) of 68In–32Bi, 50In–50Bi, and 33In–67Bi (in weight percent) low melting alloys reacted with Cu substrates were investigated. CuIn2, Cu11In9, and Cu2In IMCs formed at the interface in different In–Bi/Cu systems and were characterized by grazing incidence X-ray diffraction (GIXRD) and electron probe X-ray microanalyzer (EPMA). The CuIn2 and Cu11In9 IMCs formed at the interface phase transfer to Cu11In9 when annealing temperature was greater than 70 °C. CALPHAD-type thermodynamic calculations were performed to illustrate the corresponding diffusion paths. Moreover, shear tests were conducted and indicated that 50In–50Bi solder joint provide the highest shear strength among the three alloys.

Phosphates of Zirconium and Metals (Ni, Cu, Co, and Mn) in the Oxidation State of +2: Synthesis and Structure

The formation of phases and the structure of phosphates in the M0.5 + xM′xZr2 − x(PO4)3 systems (M = Co, Mn; M′ = Ni, Cu; 0 ≤x ≤ 2) were studied. The formation of complex phosphate phases synthesized by the sol-gel method was investigated by X-ray diffraction, electron microscopy, microprobe analysis, and IR spectroscopy. The formation of limited solid solution crystallizing in the Sc2(WO4)3 structural type was established in the studied systems. The regularities of changes in their crystallographic characteristics depending on the chemical composition were elucidated. The crystal structure of Mn1.2Ni0.7Zr1.3(PO4)3 was refined by the Rietveld method using powder X-ray diffraction data (space group P21/n, Z = 4, a = 8.8317(13) A, b = 8.9350(11) A, c = 12.4893(17) A, β = 90.027(26)°, V = 985.55(23) A3). The obtained data on the formation of M0.5 + xM′xZr2 − x(PO4)3 solid solutions (M = Co, Mn; M′ = Ni, Cu) broadened the phase formation picture for the known phosphates with octahedral-tetrahedral {[L2(PO4)3]p−}3∞ type frameworks and characterized the general trends in the size dependence of the structure of phosphates and the limits of solid solutions.

Visualization of the Sorption of Nickel within Exopolymer Microdomains of Bacterial Microcolonies Using Confocal and Scanning Electron Microscopy.

The sorption and distribution of nickel, a common metal contaminant in aquatic systems, were assessed in bacterial microcolonies using a combination of fluorescent staining with Newport Green and confocal laser scanning microscopy (CLSM) with confirmation by scanning electron microscopy (SEM) and X-ray microprobe analyses. CLSM with Newport Green, selected fluor-conjugated lectins, and DNA staining allowed for the discrimination of the microdomains present in the microcolony exopolymeric matrix and detection of bound nickel. This approach avoided the artefacts associated with drying and fixation required by analytical electron microscopy. The results obtained indicated that specific microcolonies within river biofilms sorbed nickel within limited microdomains present in the complex tripartite exopolymeric matrix surrounding bacterial cells. Sorption occurred such that nickel was concentrated within the exopolymeric matrix, but not directly associated with cells. These microdomains appeared to have neutral pH and be dominated by negatively charged residues favoring the sorption of nickel and other cations. These results also suggest an important role for specific community members in the sorption and concentration of metals in aquatic biofilm communities.

Emeritus Professor Reinhard Ferdinand Mathias Van Steveninck (1928-2017) and Dr Margaret Elva Van Steveninck (1931-2017) - plant physiologists and electron microscope X-ray microprobe specialists.

This obituary highlights the careers and contributions of two eminent plant physiologists. Emeritus Professor Reinhard Van Steveninck (1928-2017) was educated at Wageningen and London University. He joined the Department of Scientific and Industrial Research (DSIR), New Zealand, and achieved early recognition for his publications on abscission and mechanisms of salt uptake of plants. He was appointed Professor of Agriculture (Plant/Soil Science) at La Trobe University in 1976. He expanded his research into salinity tolerance of lupins and the ultrastructural localisation of ions using X-ray microprobe analysis. He was a good teacher and nurtured and trained many researchers in this area. He was a recognised expert in using a combination of ultrastructural techniques to study the movement of ions within plant cells and across tissues. His publications include book chapters on plant physiology, as well as a major review on the 'washing' or 'ageing' phenomenon in plant tissues. He was an active member and President of the Australian Society of Plant Physiologists. Margaret Van Steveninck (1931-2017) worked as a Research Assistant at Adelaide University and subsequently as a Demonstrator and Senior Demonstrator in Botany at Queensland and La Trobe University. Her plant physiology research with her husband resulted in numerous joint publications including a chapter on microanalysis in 'Electron microscopy of plant cells'.

Serpentines as the indicators of mesozoic peridotites metamorphic and geodynamic transformations in the Internal Ukrainian Carpathians

Formulation of the problem. Peridotites of ophiolite complexes,being the fragments of the oceanic upper mantle that have undergone several stages of partial melting, brought to the surface by tectonic movements, also have undergone metamorphic transformations almost immediately after its formation. Because of serpentinization, the mineral composition of the rocks became more complicated. The analysis of the final structure and composition of apoperidotites allows obtaining data for geodynamic reconstructions regarding the stage of their formation. Review of previous publications. It has been determined that serpentines are the most common secondary minerals of peridotites of the Uholskyi complex in the Ukrainian Carpathians, and the processes of serpentinization took place at a depth of 40–50 to 100 km (?) at T = 450–600 °C and P = 13–16 kbar (Stupka O., 2013). The study of serpentinites of the Main Ural Fault (Panas'yan L. et al., 2014) revealed that high alumina and high chromium serpentinites have ultrabasic protoliths formed in the mantle, and medium alumina and low chromium varieties – the protoliths of the basic composition which were born in the conditions of the crust. Based on the study of serpentinites in the orogenic Qinling belt (China), researchers (Wu K. et al., 2018) determined their mantle origin: magnetite-enriched antigorite serpentinites were formed as a result of the interaction of serpentinized apoperidotites of mantle protoliths with molten rock in the subduction channel. Purpose. We have investigated secondary serpentines in order to reconstruct the geodynamic conditions of the formation and transformations of the peridotites (Uholskyi complex), localized in the Marmarosh rocky zone in the Internal Ukrainian Carpathians, and are most widely spread in the interfluve of Velyka and Mala Uholka-rivers. Methods. The work is based on the results of geological observations of the Uholskyi complex rocks in natural outcrops, as well as petrographic, mineralogical (including X-ray diffraction, thermal and microprobe analysis), and geochemical studies. Results. The paper presents the study results of serpentinized apoperidotites of the ophiolite Uholskyi complex in the Internal Ukrainian Carpathians. Serpentinized apoperidotites (T2–K1?) form olistoliths in the Soimulska olistostrome-conglomerate strata of the Lower Cretaceous age. The investigated serpentines are the rock-forming minerals of lizardite and antigorite serpentinites. Lizardite serpentinites are characterized by lenticular-looped textures formed by α-lizardite and non-altered chrome-spinellids. Antigorite serpentinites, recognized by striped-shale textures, contain antigorite, β-lizardite and magnetite. Lizardite serpentinites are characteristic of the regressive metamorphism of the greenschist facies upper part, and antigorite serpentinites are a typical formation of the progressive metamorphism of the lower greenschist – upperlower epidote-amphibolite facies. Regressive metamorphism occurred under geodynamic conditions of spreading and the progressive ones – under subduction conditions between the terrains of Dacia and Tisza, which led to the closure of the Transylvanian-Mureş Paleocean. It has been concluded, that the protoliths of lizardite serpentinites were the primary mantle rocks of the ultrabasic (restitic) composition, and the protoliths of the antigorite serpentinites were the lithospheric rocks of the basic composition. Conclusions. The complex study of serpentinized apoperidotites of the Uholskyi complex makes it possible to reconstruct the metamorphic transformations of the primary mantle protoliths and to determine the stages of lithosphere formation within the fold-nappe structures. The obtained results can be used for prediction of serpentinite mineralization.

Synthesis, phase formation, crystal structure of M0.5(1+x)FexZr2-x(PO4)3 phosphates, M – transition metals in +2 oxidation state

Phosphates M0.5(1+x)FexZr2-x(PO4)3 (M – Ni, Cu, Zn, Mn) of scandium tungstate related structure were synthesized via sol-gel method (including Pechini technique). The samples were characterized by X-ray diffraction, IR spectroscopy, electron microscopy and microprobe analysis. Composition and temperature regions of solid solutions existence in the studied systems were revealed. The Rietveld refinement was implemented for crystal structure of Mn0.65Fe0.3Zr1.7(PO4)3 to be characterized.

Characterization of Selenium Accumulation, Localization and Speciation in Buckwheat-Implications for Biofortification.

Buckwheat is an important crop species in areas of selenium (Se) deficiency. To obtain better insight into their Se metabolic properties, common buckwheat (Fagopyrum esculentum) and tartary buckwheat (F. tataricum) were supplied with different concentrations of Se, supplied as selenate, selenite, or Astragalus bisulcatus plant extract (methyl-selenocysteine). Se was supplied at different developmental stages, with different durations, and in the presence or absence of potentially competing ions, sulfate, and phosphate. The plants were analyzed for growth, Se uptake, translocation, accumulation, as well as for Se localization and chemical speciation in the seed. Plants of both buckwheat species were supplied with 20 μM of either of the three forms of Se twice over their growth period. Both species accumulated 15–40 mg Se kg−1 DW in seeds, leaves and stems, from all three selenocompounds. X-ray microprobe analysis showed that the Se in seeds was localized in the embryo, in organic C-Se-C form(s) resembling selenomethionine, methyl-selenocysteine, and γ-glutamyl-methylselenocysteine standards. In short-term (2 and 24 h) Se uptake studies, both buckwheat species showed higher Se uptake rate and shoot Se accumulation when supplied with plant extract (methyl-selenocysteine), compared to selenite or selenate. In long-term (7 days) uptake studies, both species were resistant to selenite up to 50 μM. Tartary buckwheat was also resistant to selenate up to 75 μM Se, but >30 μM selenate inhibited common buckwheat growth. Selenium accumulation was similar in both species. When selenite was supplied, Se levels were 10–20-fold higher in root (up to 900 mg Se kg−1 DW) than shoot, but 4-fold higher in shoot (up to 1,200 mg Se kg−1 DW) than root for selenate-supplied plants. Additionally, sulfate and phosphate supply affected Se uptake, and conversely selenate enhanced S and P accumulation in both species. These findings have relevance for crop Se biofortification applications.

Lightweight ceramics based on aluminum dodecaboride, boron carbide and self-bonded silicon carbide

The correlations between structures and mechanical characteristics of α-AlB12-, AlB12C2-, B4C-based lightweight ceramics and composites synthesized or sintered by hot pressing (at 30 MPa) and SiC-based ceramics obtained by reactive sintering are compared. The effect of C, TiC and SiC additions on the properties of the resultant composites and the particularities of the ceramics destruction under shock loading are discussed. Ballistic tests performed on 10 mm thick plates fabricated from the developed ceramics (2.63 g/cm3 density; 78 wt% B4C and 22 wt% SiC composition according to X-ray diffraction analysis; B3.64CSi0.01 and SiC1.07 stoichiometry according to SEM microprobe X-ray analysis), showed that the material could withstand a 10 m distance shot using a bullet with initial kinetic energy of 3.7 kJ.

Evidence of a shallow magma reservoir below Los Humeros volcanic complex: Insights from the geochemistry of silicate melt inclusions

Los Humeros volcanic complex (Eastern Trans Mexican Volcanic belt) is one of the three most important geothermal fields in Mexico and is currently producing electricity (ca. 90 MW). It is therefore pertinent to constrain the magma chamber characteristics, such as its depth, and the magmatic evolution of the complex in order to better define the superficial geothermal activity. In this paper we present the first geochemical data (major and trace elements) for 15 silicate melt inclusions and their five host rocks from Los Humeros volcanic complex.We constrained the evolution of the volcanic complex by coupling X-ray spectrometry, ICP-MS, microprobe, X-ray microtomography and NanoSIMS analyses together with thermodynamical modeling on both whole rocks and silicate melt inclusions.A ponding reservoir located within an interval betwwen 5 and 13 km at depth is evidenced by silicate melt inclusions entrapment pressures. This ponding depth's interval is in agreement with previous studies by thermal modeling, resistivity and geobaromatry done in the same area. The geothermal activity of Los Humeros volcanic area is expected to be the result of the cooling of the magma in the shallow chamber. A large geochemical variability, in less than 1 Ma, is demonstrated by trace and volatile element compositions evolution through time. Subduction contamination is expected into the mantle source with the highest contamination event at 69 Ka, during the second caldera event of Los Humeros volcanic complex.

Fungal Endophyte Alternaria tenuissima Can Affect Growth and Selenium Accumulation in Its Hyperaccumulator Host Astragalus bisulcatus.

Endophytes can enhance plant stress tolerance by promoting growth and affecting elemental accumulation, which may be useful in phytoremediation. In earlier studies, up to 35% elemental selenium (Se0) was found in Se hyperaccumulator Astragalus bisulcatus. Since Se0 can be produced by microbes, the plant Se0 was hypothesized to be microbe-derived. Here we characterize a fungal endophyte of A. bisulcatus named A2. It is common in seeds from natural seleniferous habitat containing 1,000–10,000 mg kg-1 Se. We identified A2 as Alternaria tenuissima via 18S rRNA sequence analysis and morphological characterization. X-ray microprobe analysis of A. bisulcatus seeds that did or did not harbor Alternaria, showed that both contained >90% organic seleno-compounds with C-Se-C configuration, likely methylselenocysteine and glutamyl-methylselenocysteine. The seed Se was concentrated in the embryo, not the seed coat. X-ray microprobe analysis of A2 in pure culture showed the fungus produced Se0 when supplied with selenite, but accumulated mainly organic C-Se-C compounds when supplied with selenate. A2 was completely resistant to selenate up to 300 mg L-1, moderately resistant to selenite (50% inhibition at ∼50 mg Se L-1), but relatively sensitive to methylselenocysteine and to Se extracted from A. bisulcatus (50% inhibition at 25 mg Se L-1). Four-week old A. bisulcatus seedlings derived from surface-sterilized seeds containing endophytic Alternaria were up to threefold larger than seeds obtained from seeds not showing evidence of fungal colonization. When supplied with Se, the Alternaria-colonized seedlings had lower shoot Se and sulfur levels than seedlings from uncolonized seeds. In conclusion, A. tenuissima may contribute to the Se0 observed earlier in A. bisulcatus, and affect host growth and Se accumulation. A2 is sensitive to the Se levels found in its host’s tissues, but may avoid Se toxicity by occupying low-Se areas (seed coat, apoplast) and converting plant Se to non-toxic Se0. These findings illustrate the potential for hyperaccumulator endophytes to affect plant properties relevant for phytoremediation. Facultative endophytes may also be applicable in bioremediation and biofortification, owing to their capacity to turn toxic inorganic forms of Se into non-toxic or even beneficial, organic forms with anticarcinogenic properties.

From unweathered core to regolith in a single weathering andesitic clast: Rates and trends of in situ chemical weathering on a tropical volcanic island (Basse Terre Island, French Guadeloupe)

We conduct X-ray microprobe, chemical and U-series isotope analyses on an oriented weathering clast collected from the regolith of a weathered Quaternary volcanoclastic debris flow on Basse Terre Island, French Guadeloupe. The sample consists of an unweathered basaltic andesite core surrounded by a weathering rind, and an indurated crust that separates the rind from the overlying soil matrix. U/Th disequilibria dating indicates that rind age increases away from the core-rind boundary to a maximum of 66 ka. This translates to a rind-advance rate of ~0.2 mm kyr−1, broadly consistent with rind advance rates calculated elsewhere on Basse Terre Island. The overlying indurated crust is 72 ka, indicating a possible minimum duration of the rind formation. Elemental variations are constrained by a bulk chemical analysis along a vertical transects from the core to the overlying soil matrix and parallel electron microprobe analyses. The hierarchy of elemental loss across the core-rind boundary varies in the order Ca > Na ≈ Mg > K > Mn > Si > Al > Ti = 0 > P > Fe, consistent with the relative loss of phases in the clast from plagioclase ≈ glass ≈ pyroxene > apatite > ilmenite. The abrupt, <900 μm wide, Ca, Na and porosity reaction fronts at the core-rind boundary approximately equal the length of the long dimension of plagioclase phenocrysts observed in the unweathered core. The <1000 μm wide reaction front at the rind-soil interface is marked by an indurated horizon with Fe and Mn enrichment that spans into enrichment of Mn, Ba, Al, Mg and K in the soil matrix. Unlike previously studied clasts, the preservation of the rind-soil interface permits characterization of weathering reactions and material exchanges between the weathering core, the rind, and the surrounding soil matrix, shedding insights into communication between the enveloping weathering rind and host regolith. The lack of an enrichment signal of Mn within the weathered rind suggests that weathering processes active within clasts are distinct from surrounding soil formation processes.

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.

Durability Test of Anode-Supported Solid Oxide Fuel Cell Under Diverse Load Conditions

Solid oxide fuel cells (SOFCs) provide an appealing electrochemical devices to convert chemical energy into electrical power with high efficiency and negligible carbon emissions. For utilizing in a wide spectrum of applications, SOFCs need to prove the operational stability over 40,000 h with less than 10% of power decay [1]. The performance deteriorations of SOFCs are induced by complex factors such as redox cycle [2], carbon deposition [3], S poisoning [4], and Cr poisoning. Therefore, understanding of fundamental degradation mechanisms under various operating conditions are important to improve the lifetime of SOFCs. For past few decades, the durability study of SOFCs has carried out under prolonged periods of time in mainly ‘laboratory conditions’, i.e. constant current operations, well controlled fuel composition, and low level of impurities [5,6]. However, the real operating conditions normally include harsh conditions such as temperature fluctuations, current fluctuations, and fuel and air stop. Especially, the different load conditions can result in accelerating the degradation of cell components because of the local potential and temperature changing. In this research, systematic durability investigations of anode-supported SOFCs are performed under a wide range of operating conditions including load cycle and load trip. In order to understand degradation mechanisms of the cell, various electrochemical investigations are performed such as the current-voltage polarization and electrochemical impedance spectroscopy. The morphology and microstructure of anode-supported cell are examined using field emission scanning electron microscoy and electron probe X-ray microanalyzer. References Y.-S. Chou, J.W. Stevenson, J.-P. Choi, J. Power Sources 250 (2014) 166–173.T. Klemensø, C. Chung, P.H. Larsen, M.Mogensen, J. Electrochem. Soc. 152 (2005) A2186–A2192.Mai, M. Becker, W. Assenmacher, F. Tietz, D. Hathiramani, E. Ivers-Tiffee, D. Stöver, W. Mader, Solid State Ionics 177 (2006) 1965–196H. Yokokawa, T. Horita, K. Yamaji, H. Kishimoto, T. Yamamoto, M. Yoshikawa, Y. Mugikura, K. Tomida, Fuel Cells 13 (2013) 526–535.Hagen, J.V.T. Høgh, R. Barfod, J. Power Sources 300 (2015) 223–228.H. Yokokawa, ECS Trans. 35 (2011) 207–216.T.-H. Lee, K.-Y. Park, J.-T. Kim, Y. Seo, K.B. Kim, S.-J. Song, B. Park, J.-Y. Park, J. Power Sources 276 (2015) 120–132.

Effect of co-site dilution on the magnetism of RCo5 (R = Gd, Y) compounds

The magnetic and magnetocaloric properties of the RCo5−xGax (R = Gd, Y; x = 1, 1.5, 1.6, 1.7) compounds have been studied. X-ray and electron microprobe analysis show that the samples are single phase and crystallize in the hexagonal CaCu5 - type structure (space group P6/mmm, N 191, hP6). The magnetic properties have been studied from 2 to 400 K under magnetic fields in the region of 1 to 140 kOe. With increasing Ga amount the magnetic ordering temperature decreases rapidly. The increase in Ga concentration leads to the reduction of the magnetic moment of Co sublattice and the Curie temperature. It has been found that the paramagnetic susceptibility follows the Néel-type law for GdCo5−xGax (x = 1.5, 1.6, 1.7) and the Curie-Weiss law for YCo3.3Ga1.7. The molecular field coefficients and sublattice magnetizations were determined on a basis of the Néel theory and experimental data. The magnetocaloric effect and refrigerant capacity have been estimated over a wide temperature range of 10–350 K.

Embreyite: structure determination, chemical formula and comparative crystal chemistry

ABSTRACTEmbreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of microprobe analysis is Pb1.29Cu0.07Cr0.52P0.43O4(without taking into account the presence of H2O). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic,C2/m,a= 9.802(16),b= 5.603(9),c= 7.649(12) Å, β = 114.85(3)oandV= 381.2(11) Å3) has been solved by direct methods and refined toR1= 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in bothdvalues and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were re-calculated for the holotype sample using a new cell setting and correspondinghklindices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6distorted octahedra. The interlayer space is filled by disordered Pb2+and Cu2+cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O4]2]} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (Pbx$M_y^{2 +} $□1–x–y)2{Pb[(Cr,P)O4]2}(H2O)n, whereM2+= Cu and Zn and 0.5 ≤x+y≤ 1, or, in the simplified form: (Pb,Cu,□)2{Pb[(Cr,P)O4]2}(H2O)n. The simplified formula of embreyite is similar in stoichiometry to vauquelinite and may explain the existence of the solid-solution series. The determination of the crystal structure of embreyite may also help to resolve the crystal chemical nature of cassedanneite. The XRD pattern of cassedanneite contains a distinct reflection withd= 13.9 Å, forbidden for the embreyite unit cell. This feature may indicate the doubling of thecunit-cell parameter of cassedanneite in comparison with embreyite. We assume that cassedanneite has structural similarity to embreyite with, presumably, a disordered distribution of Cr and V.

Synthesis and crystal structure of phosphates Zn0.5(1+x)FexM2-x(PO4)3 (M = Zr, Hf)

New phosphates Zn0.5(1+x)FexM2-x(PO4)3 (M = Zr, Hf; 0 ≤ x ≤ 2.0) were synthesized via sol-gel and solid-state methods. The obtained solid solutions were characterized by X-ray diffraction, IR spectroscopy, electron microscopy and microprobe analysis. It was established that the phosphates crystallize in the structural types of Sc2(WO4)3 (SW) and NaZr2(PO4)3 (NZP). Rietveld refinement was implemented for structure of the phosphates Zn0.7Fe0.4Zr1.6(PO4)3 and Zn0.85Fe0.7Hf1.3(PO4)3 to be characterized. The formation regions of the solid solutions were revealed, and the temperature stability of the samples was also determined. Different limits of solid solutions were defined for the zirconium phosphates which had been synthesized via sol-gel and solid-state methods, and the reason for that is the low thermal stability of the SW-phosphates with high x values.

Ways to Improve the Quality of Die Steel 5KhNM

There was performed an analysis of influence of the deoxidation technology, hydrogen content and high concentration of titanium in steel 5KhNM (Rus. “5XHM”) on quality of die blanks, evaluated based on the results of the ultrasonic test.The fractographic examinations of fractures and the X-ray microprobe analysis of chemical composition of non-metallic inclusions were conducted, the evaluation of macro- and micro-structure of a die blank with high titanium content was performed.It is demonstrated that defects of dies from steel 5KhNM (Rus. “5XHM”) are cracks from merged flakes and micro-flakes; in most cases large concentrations of sulphides appeared to be hydrogen collectors for formation of flakes and micro-flakes.

Chemical Metallization and Morphology of the Surface of a Copper-Plated Poly(Ethylene Terephthalate) Fiber

The possibility of chemical metallization of the surface of poly(ethylene terephthalate) (lavsan) fibers in solutions using hydrazine sulfate as a reducing agent is shown. As a result, a conductive material is obtained. The surface of lavsan fibers is activated by treating the fibers in caustic ammonia with ultrasound treatment and processed in alkaline solutions. The elemental composition and surface morphology of the metalized fibers are characterized using X-ray diffraction, microprobe analysis, and scanning electron microscopy. The surfaces of metallized fibers treated with various copper-plating solutions are shown to be coated by copper layers of 4 μm thickness, having good adhesion. The coating is uniform and defect-free over the entire length of the fibers. The fiber electrical resistivity is 0.4–0.9 Ω/cm.