Electron Probe X-ray Analysis Research Articles

Electron Probe X-Ray Analysis of Nanofilms at Off-Normal Incidence of the Electron Beam

The frontier of the electron probe X-ray spectral method in the determination of trace metal quantities on a silicon substrate is studied. The experimental data are acquired for ultrathin chromium films on a silicon substrate. It is shown that the signal-to-noise ratio significantly increases at a noticeable sample inclination (80°), which allows one to determine an extremely low (available by this approach) chromium content. The calibration curve for the inclined sample position is plotted using the Monte Carlo method. The surface concentration of chromium atoms (2.2 ± 0.4) × 1014 cm–2 and the chromium detection limit (5 × 1013 cm–2) are measured under the given experimental conditions. For the electron probe X-ray microanalysis of bulk samples, it is a record value. The equivalent weight of chromium at the aforementioned surface concentration is approximately 4 × 10–18 g. The proposed technique requires no changes in the design of the device to be applied.

STRUCTURAL-PHASE STATE OF COATINGS OF THE SYSTEM OF Ni – Cr – B – Si – Fe/WC AFTER PLASMA-POWDER SURFACING WITH THE USAGE OF NANOPOWDERS

The paper presents the results of the comparative researches of structural-phase states and internal stress fields of plasma-powder surfaces of the system of Ni – Cr – B – Si – Fe/WC with the use of a modifier in the form of nanodisperse particles of Al2O3 and without it. Using the methods of transmission diffraction electron microscopy on thin foils, scanning electron microscopy, X-ray structure and electron probe X-ray analysis, the authors have conducted the researches of powder alloy PS-12NVK-01, welded on a substrate of steel 20. The phase composition has been defined, as well as defect structure and internal stresses. The material structure has been studied before and after the introduction of nanopowder Al2O3 into the melt. It has been established that the introduction of the modifier leads to the decrease of the material grain size, to the formation of tungsten carbide W2C and boride Fe3Ni3B in a carbide subsystem, as well as to the decrease of the internal stress values and dislocation scalar density .

Effect of B2O3 on reduction of FeO in Ti bearing blast furnace primary slag

The effect of B2O3 on reduction of FeO from iron saturated FeO–CaO–SiO2–MgO–Al2O3–TiO2 slags by graphite has been studied under static conditions between 1473 and 1573 K. The compositions of quenched samples were determined by electron probe X-ray analysis (EPMA). The reduction degree (R) of FeO in each sample was obtained by mass balance and compared with the reduction of FeO in the slags without B2O3. The results showed that FeO reduction in the primary slag was effectively improved with only 1 mass-% B2O3 content, but did not continue to increase with the increase in B2O3 content and it reduced slightly at about 3 mass-%B2O3. After reduction B2O3 gathered in the liquid phase where it can restrain the formation of iron–titanium oxide and promote the reduction of FeO, so benefiting blast furnace operation.

Effect of microabsorption heterogeneity in the X-ray fluorescence analysis of ultrafine particles

The dependence of the intensity (I i ) of X-ray fluorescence on the size (D) of finely ground particles was studied for saturated and unsaturated samples. It was found that even at the wet grinding (addition of ethanol) of powders with D < 10 μm, the aggregation and covering of larger grains (α) with smaller grains of different compositions occur, which changes the character of the dependence I i = f(D), particularly, if fluorescence is emitted by the grains α. The nature of the observed effects is proved by the results of granulometric analysis and by electron probe X-ray analysis. In the transition from saturated to unsaturated samples, the discussed effects are enhanced.

Behavior of Two Titanium Alloys in Simulated Body Fluid

ABSTRACTTitanium possesses an excellent corrosion resistance in biological environments because the titanium dioxide formed on its surface is extremely stable. When aluminium and vanadium are added to titanium in small quantities, the alloy achieves considerably higher tensile properties than of pure titanium and this alloy is used in high stress-bearing situations. But these metals may also influence the chemostatic mechanisms that are involved in the attraction of biocells. V presence can be associated with potential cytotoxic effects and adverse tissue reactions. The alloys with aluminium and iron or with aluminium and niobium occur to be more suitable for implant applications: it possesses similar corrosion resistance and mechanical properties to those of titanium-aluminium-vanadium alloy; moreover, these alloys have no toxicity.In this paper, pure Ti, Ti-6Al-7Nb and Ti-6Al-4Fe with a nanostructured surface were studied. Data about mechanical behavior are presented. The mechanical behavior was determined using optical metallography, tensile strength and Vickers microhardness.For the electrochemical measurements a conventional three-electrode cell with a Pt grid as counter electrode and saturated calomel (SCE) as reference electrode was used. AC impedance data were obtained at open circuit potential using a PAR 263A potentiostat connected with a PAR 5210 lock-in amplifier. The ESEM and EDAX observation were carried out with an environmental scanning electronic microscope Fei XL30 ESEM with LaB6-cathode attached with an energy-dispersive electron probe X-ray analyzer (EDAX Sapphire). After 3 days of immersion in simulated body fluid the nucleation of the bone growth was observed on the implant surface.It resulted that the tested oxide films presented passivation tendency and a very good stability and no form of local corrosion was detected. The mechanical data confirm the presence of an outer porous passive layer and an inner compact and protective passive layer. EIS confirms the mechanical results. The thicknesses of these layers were measured. SEM photographs of the surface and EDX profiles for the samples illustrate the appearance of a microporous layer made up of an alkaline titanate hydrogel. The apatite-forming ability of the metal is attributed to the amorphous sodium titanate that is formed on the metal during the surface treatment.The results emphasized that the surface treatment increases the passive layer adhesion to the metal surface and improves the biocompatibility of the biomedical devices inducing the bone growth on the implant surface.

In vitro and in vivo studies of alkali‐ and heat‐treated Ti‐6Al‐7Nb and Ti‐5Al‐2Nb‐1Ta alloys for orthopedic implants

In vitro studies of Ti-6Al-7Nb and Ti-5Al-2Nb-1Ta alloys were carried out by treating the specimens with 10 M NaOH at 60 degrees C for 24 h and subsequently heat-treated at 600 degrees C for 1 h. After the alkali and heat treatments, and on subsequent soaking in simulated body fluid (SBF), the morphological and compositional changes on the surface of the specimens were examined using scanning electron microscope attached with an energy-dispersive electron probe X-ray analyzer. The results revealed a dense and uniform bonelike apatite layer on the surface of treated substrates immersed in SBF solution. In vivo studies were carried out in rats to evaluate osteoconduction of Ti-6Al-7Nb and Ti-5Al-2Nb-1Ta alloys surface after alkali and heat treatments compared with untreated titanium alloys as the control. The following titanium implants were prepared from these species: (1) control without implant; (2) untreated titanium implant; (3) alkali- and heat-treated implant--the implants were immersed in 10 M NaOH solution at 60 degrees C for 24 h and subsequently heated at 600 degrees C for 1 h. The specimens were inserted into the medial side of each tibia of rats. Histologically, direct bone contact with the implant surface was significantly higher in the alkali heat-treated implants than the untreated titanium implants.

Elemental fractionation and stoichiometric sampling in femtosecond laser ablation

Elemental fractionation in femtosecond laser ablation is studied by ICP-MS by applying successive single laser shots to binary metallic and semiconductor samples as well as to multi-component glasses. Fractionation can be observed in the first laser shots in particular if the laser fluence is near the ablation threshold of the sample. However, the element ratio in the laser-sampled masses changes from shot to shot until it reaches an asymptotic fluence-independent value representing stoichiometric sampling. The asymptotic stoichiometric ratios can be obtained with fewer shots if higher laser fluences are applied. It is shown by electron probe X-ray analysis that different elemental ablation probabilities modify the element compositions in the surface layers of the laser craters until equilibrium conditions are obtained. These conditions can be reached by applying many shots of low laser fluence or with one high-fluence laser shot only. The experimental data reveal that in most cases the elemental ablation probability can be correlated with the respective ionization energies of the elements, i.e., the elements with lower first ionization energy have higher ablation probability. No or only very weak fractionation was observed when elements with nearly the same ionization energies were sampled.

Dimethyl adipate hydrogenation at presence of Pt based catalysts

Dimethyl adipate hydrogenations catalyzed by Pt/Al 2O 3 and Pt/TiO 2 have been studied. Catalysts were prepared with the conventional impregnation method. Physical–chemical characterization of the catalytic systems was made with the use of different techniques: N 2 and H 2 sorption, scanning electron microscopy (SEM), energy-dispersive electron (EDS) probe X-ray analysis, temperature programmed reduction (TPR) and inductively coupled plasma optics emission spectrometry (ICP-OES). Metals dispersion in the catalysts is directly related to the superficial area of the supports, and partially covered particles (in the case of the TiO 2) can be present. Support modifies the behavior of metals in its surface for different ways: SMSI effect (TiO 2) or acidity (Al 2O 3). The catalyst supported on Al 2O 3 is more active, reaching 52.91% conversion after 10 h of reaction, while at the same period of time, the catalyst supported on TiO 2 converted only 15.56% of the substrate. Methyl caproate, adipic acid mono-methyl ester and caprolactone were obtained as main products by Pt/Al 2O 3 catalyst. These products indicate that carboxylic groups have not been activated enough, leading to formation of significant amount of hydrogenation products different from 1,6-hexanediol (diol). Pt/TiO 2 catalyst obtained methyl caproate, caprolactone, hexane and diol, where hexane formation occurred from methyl caproate. Diol formation occurred after 5 h of reaction and it indicates participation of platinum and TiO 2 as active catalytic sites.

Isothermal Section of the Phase Diagram of the Ce—Pt—Si Ternary System at 600 °C.

Abstract The interaction of the components in the Ce–Pt–Si system at 600 °C was investigated over the whole concentration range by X-ray powder and single crystal diffraction, DTA, and electron probe X-ray analysis. There are nine ternary compounds in the Ce–Pt–Si system. The crystal structures of eight of them were determined.

Ce—Ti—Ge System at 1170 K.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Isothermal section of the phase diagram of the Ce–Pt–Si ternary system at 600 °C

The interaction of the components in the Ce–Pt–Si system at 600°C was investigated over the whole concentration range by X-ray powder and single crystal diffraction, DTA, and electron probe X-ray analysis. There are nine ternary compounds in the Ce–Pt–Si system. The crystal structures of eight of them were determined.

Microstructure and Strength of Sn-Bi Coated Sn-3.5 mass%Ag Solder Alloy

Sn-Bi coated Sn-3.5 mass%Ag solder alloy was investigated as a possible low melting temperature solder. Electroplating method was used to form Sn-Bi coated solder alloy on the Sn-3.5 mass%Ag alloy. Sn-Bi coated solders were bumped on the FR-4 substrate and Cu plates by a reflow machine at different temperatures. The die shear strength and microstructure were evaluated with scanning electron microscope (SEM). The compositions of Sn-Bi coated solder, and Bi distribution of solder were studied by electron probe X-ray analyzer (EPMA). The Sn-Bi coated Sn-Ag solder was possible to be bonded at low temperature such as 473-523 K and it is comparable to Sn-37%Pb solder. Intermetallic compounds (IMC’s) along the bonded interface were well formed in the coated solder composed of high Bi and the compositions consisted of 59.49 at%Sn-37.20 at%Cu-3.31 at%Ag. Cu6Sn5 and Ag3Sn intermetallics were observed at the interface as well as inside of the solder. Bi segregation in the solder and at the IMC was not observed. The die shear strength was 3.6384 N and increased as coated Sn-Bi thickness increases.

Dy—Sb—Si System at 1100 K and Ternary Intermetallic Phases in the Dy—Sb—Si and Gd—Sb—Si Systems.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Observation of Strong Absorption of the Yttrium Lα Line in Sialon Ceramics

β-sialon ceramics sintered with yttria additives have been studied with the use of an electron probe X-ray analysis (EPMA). Sialon ceramics were prepared from a carbothermally derived β-sialon powder and then sintered in a nitrogen atmosphere with yttria admixture. The above process was followed by annealing in flowing nitrogen. Scanning electron microscope (SEM) observations have shown that the sintered material contains a glassy phase (Y-Si-Al-O-N) on the grain boundaries. X-ray diffraction (XRD) after annealing in nitrogen revealed the presence of a considerable amount of yttrium aluminium garnet (YAG). The higher voltage of 30 kV was used in order to excite the yttrium Kα radiation (14.96 keV) at an appropriate overvoltage ratio because in some phases of the material, the disappearance of the yttrium Lα line has been observed during EPMA examination at an accelerating voltage of 15 kV in energy dispersive spectra (EDS). The intensity of the yttrium Kα line was sufficiently high, while the Y Lα line was not seen in the ED spectrum. Because the position of the yttrium Lα line (1.922 keV) is very close to the Si (K) absorption edge (1.84 keV), the strong absorption at this edge is probably responsible for the effect. This result should be considered as a serious warning in the case of EPMA (EDS) studies on compounds or mixtures suspected to contain both silicon and yttrium, because at electrons energies lower than 15 keV, the presence of yttrium in materials can go unnoticed. In wavelength dispersive spectra (WDS) obtained at 15 keV the intensity of the yttrium Lα line was also very low but measurable.

Thin film analysis of chromium-phosphate conversion coatings on aluminium probed by ToF-SIMS and electron probe x-ray analysis

Time-of-flight SIMS was used to study chromium phosphate conversion layers on Al. During coating formation, fluorine is buried under a layer of CrPxOy as the layer thickens, yielding a duplex layer structure. Electron probe x-ray microanalysis was used to assess the variation in elemental composition of the coating. Preliminary results demonstrate a number of problems related to quantitative analysis of the coatings studied. Copyright @ 2000 John Wiley & Sons, Ltd.

Phase equilibria in the Tb–Ti–Ge system at 1070 K

Physico-chemical analysis techniques, including X-ray phase analysis, electron probe X-ray analysis, differential thermal analysis and metallographic analysis were employed in constructing the isothermal section of the Tb–Ti–Ge system at 1070 K. The formation of the following ternary intermetallic compounds were detected in the Tb–Ti–Ge system at 1070 K: TbTiGe (high-temperature modification of CeFeSi structure type, space group P4/ nmm, a=0.4050(2) nm, c=0.7652(3) nm: low-temperature modification of La 2Sb structure type, space group I4/ mmm, a=0.4053(2) nm, c=1.5293(3) nm) and Tb 22...15Ti 34...41Ge 44 (Sm 5Ge 4 structure type, space group Pnma, a=0.7019(1)...0.6889(5) nm, b=1.3457(2)...1.332(1) nm, c=0.7156(1)...0.755(1) nm). The TbGe 3.5 compound belongs to the ThGe 2 structure type (space group Cmmm, a=2.0738(4) nm, b=0.4043(1) nm, c=0.3914(1) nm). The high-temperature modification of the Th 2Ge 3 compounds belongs to the ThSi 2 structure type (space group I4 1/ amd, a=0.4061(2) nm, c=1.372(1) nm).

Phase equilibria in the {Sm,Tb,Tm}–Mn–Si systems at 870/1070 K: Structural data and melting temperatures of some ternary compounds in the R–Mn–Si systems (R=Y, La–Lu)

Physico-chemical analysis techniques, including X-ray phase analysis, electron probe X-ray analysis, differential thermal analysis and metallographic analysis were employed in investigations of phase diagram of the {Sm,Tb,Tm}–Mn–Si systems at 870/1070 K and some RMnSi, RMn2Si2, R2Mn3Si5 compounds of the R–Mn–Si systems (R=Y, La–Lu).The isothermal sections of the {Sm,Tb,Tm}–Mn–Si systems at 870/1070 K are constructed.TbMnSi (a=0.6977(1) nm, b=0.4082(1), c=0.7957(2) nm), DyMnSi (a=0.6944(1) nm, b=0.4060(1) nm, c=0.7939(2) nm), HoMnSi (a=0.6885(2) nm, b=0.4026(2) nm, c=0.7884(3) nm) and ErMnSi (a=0.6881(1) nm, b=0.4016(1) nm, c=0.7900(2) nm) belong to the TiNiSi-type structure (space group Pnma).The melting temperatures of the some ternary compounds of the R–Mn–Si systems have been measured.

A layer growth mechanism proposed on studies on a gas nitrided AISI 316 L austenitic stainless steel

In this work an austenitic stainless steel AISI 316 L (1.4404) was gas nitrided at 540°C. The nitride layer was characterised by means of X-ray analysis, SEM, TEM and electron probe X-ray analysis. A fine lamellar structure comprising ∊ and γ' nitrides was formed. Nickel paritioned into γ'-Fe4N type nitride while chromium partitioned into the ∊-Fe2–3N type nitride. A layer formation mechanism was proposed considering a local partition of the alloying elements Cr and Ni. In der vorliegenden Arbeit wurde ein austenitischer nichtrostender Stahl 1.4404 (AISI 316 L) bei 540°C gasnitriert. Die Verbindungsschicht wurde durch Röntgen-phasenanalyse, Rasterelektronenmikroskopie (REM), Transmissionselektronenmikroskopie (TEM) und Elektronenstrahlmikroanalyse untersucht. Es bildet sich ein feinlamellares Gefüge mit ∊ und γ' Nitriden, die durch eine höhere Aufnahme von Chrom im ∊-Fe2–3N und eine höhere Aufnahme von Nickel im γ'-Fe4N wuchsen. Ausgehend von der örtlichen Verteilung der Legierungselemente Cr und Ni wird ein Schichtwachstumsmechanismus vorgeschlagen.

The preparation of (BEDO-TTF) 2Cl·3H 2O salt in Bu 4NHgX 3 + Bu 4NX + 1,2-dichloroethane system. Shubnikov-de Haas oscillations

Electrochemical oxidation of BEDO-TTF (bis(ethylenedioxo)tetrathiafulvalene) in 1,2-dichloroethane in the presence of Bu 4NHgX 3 + Bu 4NX (X = I, Br, Cl) as a supporting electrolyte at low current density results in the isolation of (BEDO-TTF) 2Cl · 3H 2O salt. Its composition has been established by a chemical analysis (Cl, C, H), electron probe microanalysis and X-ray analysis. The temperature dependence of the resistance has been studied down to 1.5 K at a pressure up to 30 kbar and at room temperature up to 80 kbar. Field and angular dependences of magnetoresistance have been investigated.

Phase equilibria in the Sm{{Ru,Rh}}{{Si,Ge}} systems at 870 K

Physico-chemical analysis techniques, including X-ray phase analysis and electron probe X-ray analysis were employed in constructing the isothermal cross-section of the phase diagrams Sm{{Ru,Rh}}{{Si,Ge}} systems at 870 K. The formation of the new ternary intermetallic compounds, Sm 2RuGe 2, Sm 2RhGe 2 (structure type Zr 2CoSi 2); Sm 3Ru 2Si 2, Sm 3Rh 2Si 2, Sm 3Rh 2Ge 2 (structure type La 3Ni 2Ga 2); SmRh 5Si 3, SmRh 5Ge 3 (structure type UCo 5Si 3); Sm 2Ru 3Si 5 (structure type Sc 2Fe 3Si 5); SmRu 3Si 2 (structure type LaRu 3Si 2); SmRuSi 3 (structure type BaAl 4); Sm 33Rh 20Ge 47 (structure type AlB 2); Sm 25Rh 19Ge 56 (structure type CeRh 1 − x Ge 2 + x ); Sm 2RhGe 6 (structure type Ce 2CuGe 6) and Sm 62Ru 28Ge 10, SmRu 3Si, Sm 2RuSi 2. Sm 62Ru 10Si 28, Sm 33Rh 50Si 17, Sm 16Rh 68Si 16, SmRh 3Si 6, Sm 37Rh 35Si 28, Sm 2RhSi 2, Sm 4Rh 4Si, Sm 33Rh 53Ge 14, SmRh 2Ge, Sm 18Rh 64Ge 18, SmRh 3Ge 6, were detected in Sm(Ru,Rh)(Si,Ge) systems. It was found that compound SmRuSi does not belong to the structure type PbFCl. Ternary compound SmRuGe was not found in SmRuGe system at 870 K.