Auger Electron Spectroscopy Research Articles

Electrochemical Surface Nanostructuring of Ti47Cu38Fe2.5Zr7.5Sn2Si1Ag2 Metallic Glass for Improved Pitting Corrosion Resistance

Ti‐based bulk metallic glasses are envisioned for human implant applications. Yet, while their elevated Cu content is essential for a high glass‐forming ability, it poses biocompatibility issues, necessitating a reduction in near‐surface regions. To address this, surface treatments that simultaneously generate protective and bioactive states, based on nanostructured Ti and Zr‐oxide layers are proposed. An electrochemical pseudo‐dealloying process using the bulk glass‐forming Ti47Cu38Fe2.5Zr7.5Sn2Si1Ag2 alloy is defined. Melt‐spun ribbons are immersed in hot concentrated nitric acid solution, monitoring the anodic polarization behavior. From the current density transient measurements, together with surface studies (field‐emission scanning electron microscopy, transmission electron microscopy, and Auger electron spectroscopy), the surface reactions are described. This nanostructuring process is divided into three stages: passivation, Cu dissolution, and slow oxide growth, leading to homogenous nanoporous and ligament structures. By tuning the applied potential, the pore and ligament sizes, and thickness values are adjusted. According to X‐ray photoelectron spectroscopy, these nanoporous structures are Ti and Zr‐oxides rich in hydrous and nonhydrous states. In a simulated physiological solution, for those treated glassy alloy samples, complete suppression of chloride‐induced pitting corrosion in the anodic regime of water stability is achieved. This high corrosion resistance is similar to that of clinically used cp‐Ti.

A Novel Method for Preparation of Al–Ni Reactive Coatings by Incorporation of Ni Nanoparticles into an Al Matrix Fabricated by Electrodeposition in AlCl3:1‐Eethyl‐3‐Methylimidazolium Chloride (1.5:1) Ionic Liquid Containing Ni Nanoparticles

Al/Ni reactive coatings are fabricated via electrochemical deposition (ECD) at different applied voltages for reactive bonding application. :1‐ethyl‐3‐methylimidazolium chloride ([EMIm]Cl) (1.5:1) ionic liquid electrolyte is used as source of Al, whereas Ni is in the bath and incorporated into final coatings as nanoparticles (NPs). Scanning electron microscopy and Auger electron spectroscopy reveal a homogeneous Ni particle dispersion, as well as a high amount of particle incorporation into the Al matrix. A maximum of 37 wt% (22 at%) of Ni is detected via atomic absorption spectroscopy in the Al/Ni coating deposited at −0.1 V from an electrolyte containing 20 g L−1 of Ni NPs. Previous literature show that for bonding application an ideal concentration is around 50 at% of Ni and 50 at% Al. However, this is achieved using high vacuum, time‐consuming processes, and costly techniques like evaporation and magnetron sputtering. The ECD used in this work represents a more cost‐efficient approach which is not reported up to date for the aforementioned application. The reactivity of the coatings is confirmed by Differential scanning calorimetry. Herein, an exothermic reaction is detected upon the mixing of Al and Ni occurring at high temperatures.

Failure analysis of heavy ion-irradiated silicon carbide junction barrier Schottky diodes

An analysis of damage, including single event burnout (SEB) and single event leakage current (SELC) caused by heavy ion irradiation in silicon carbide (SiC) junction barrier Schottky diodes (JBSDs), was performed using Auger electron spectroscopy (AES), emission microscope (EMMI), focused ion beam (FIB), transmission electron microscopy (TEM) and other methods. The damage of SEB extending from the Schottky contact through the epitaxial layer to the SiC substrate was observed. The damage causing SELC was related to the micro-burnout of the Schottky contact. It was concluded that the damage of Schottky contact was induced by incident high-energy particles under a large electric field, forming a leakage current path, resulting in SEB and SELC in the SiC device.

Effects of Spectrum Loading and break in period using molybdenum disulphide (MoS2) and zinc dialkyl dithiophosphate (ZDDP) as EP additives in lithium based grease

PurposeThe purpose of variable loading conditions (392 N-785N-392N-785N) with break-in period were used to study interactions between zinc dialkyl dithiophosphate (ZDDP) 0.1 P% (phosphorus) and fine-grade molybdenum disulfide (MoS2) 3%, in different mixtures of NLGI 2 lithium stearate grease. Four-ball wear tests were used to evaluate the tribological properties of different grease mixtures such as coefficient of friction and wear. ASTM 2266 as reported by earlier studies is useful, but it is not representative of real-life applications where variable loads and speeds and different break-in periods play a role and could change the results and the nature of tribofilms.Design/methodology/approachIn this study, chemical and mechanical properties of tribofilms were examined. Moreover, design of experiment was used to examine the data and shorten experimentation time. Research described here is investigating variable loading conditions for real-life applications by using a break-in period of 2 min at the start to minimize asperities and establish a clean surface. Design expert (DOE) analyzes responses to reveal those variables that are single factor and those that are multifactor whether synergistically or antagonistically.FindingsThe results indicated that spectrum loading with break-in period showed reduction in wear when tested in greases with ZDDP/MoS2 combinations. Ramping up or down the load every 7.5 min for a rotational speed of 1,200 rpm and a total of 36,000 revolutions or 30-min time slowed the wear properties of lithium-based grease under different MoS2 and ZDDP concentrations. Experiments indicated that wear was largely dependent on the loading condition and ZDDP additives during specific break-in period at 1,200 rotational speed. It is believed that MoS2 greases perform better under spectrum loading and under constant loading when mixed with ZDDP phosphorus.Originality/valueThis research indicates that there is a synergistic interaction between ZDDP, MoS2 and variable loading especially when a break-in period is applied. The results indicated that wear was largely dependent on the specific speed used with spectrum loading as presented in the energy dispersive spectroscopy and the Auger electron spectroscopy analysis, and thus a 3% MoS2 grease with ZDDP (phosphorus: 0.1 Wt.%) are needed to improve the wear resistance and improve the friction characteristics.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2024-0016/

Si(111) islands on β-phase Si(111)√3 × √3R30°-Bi

β-phase √3 × √3R30°-bismuth (Bi) on silicon (Si)(111)7 × 7 surface has been exploited as a template for growing Si films. Two-dimensional Si islands with √3 × √3 reconstruction, parallel to that of Si(111)√3 × √3R30°-Bi, have been resolved by means of scanning tunneling microscopy, grazing-incidence X-ray diffraction (XRD) and low electron energy diffraction. Auger electron spectroscopy and scanning tunneling spectroscopy gave interesting electronic features on two-dimensional Si islands, with the evidence of a reduced band gap to ~0.55 eV, related to the presence of the underneath Bi layer, and atomic structural properties typical of Si(111). These experimental findings fully confirm the recently reported calculation based on the first-principles density functional theory, on the prediction of Si(111) growth on top of β-phase √3 × √3R30°-Bi/Si(111)7 × 7 reconstruction, shedding new light on silicon structures.

Phase transformation sequence of amorphous nickel-molybdenum electrodeposit

In this paper, the amorphous Ni-Mo alloy with cauliflower-like morphology is successfully prepared by electrodeposition, and the effects of heat treatment on its morphology, element content and structure are studied. The results of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) show that, when the temperature is higher than 600 ℃, the fine grains gradually appear and then cover the entire surface of Ni-Mo alloy. The Ni-Mo alloy occurs simultaneously the segregation phenomenon and the Mo content increases on the surface. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis illustrate that the Ni-Mo alloy gradually transfers from amorphous into crystalline structure, and the first phase MoNi4 and the second phase MoNi precipitate near 633℃ and 707℃ respectively. The apparent activation energy is 234.1 kJ/mol (ΔEa1) for the first phase crystallization and 819.9 kJ/mol (ΔEa2) for the second phase crystallization. The HER catalytic activity of Ni-Mo alloy increases first and then decreases with the increase of heat treatment temperature.

Deuterium permeation of low-activation vanadium alloys possible for reuse in a short time in fusion reactors

Low-activation vanadium (V) alloys are alternative to reduced-activation ferritic/martensitic steels for the blanket structural material. To make the reusage of the alloys possible in a short time, new-design concepts of V alloy have been suggested in National Institute for Fusion Science. In the present study, the deuterium permeation properties of the new-designed V alloys were investigated.The new-designed V-4Cr-4Ti alloy samples with high and low purity, named H44 and L44, respectively, were used. For comparison, the NIFS-HEAT-2 V alloy samples, named NH2 were also used.It was found from the permeation experiments that deuterium permeability coefficient of L44 was smaller than that of NH2, while the permeability coefficient of H44 was comparable with NH2. These results suggest the permeation coefficient of D of the new-designed V alloy was similar to those of the conventional V alloy, if Ti and O content was the same. Estimated activation energies of diffusion and permeation indicated that the permeation behaviors significantly depended on titanium oxides at the surface and in the bulk. Data obtained by a microscope with Auger electron spectroscopy indicated that the concentration and the composition of the oxide must change with air exposure during the maintenance and with hydrogen isotope exposure during the reactor operation. The obtained results suggest these changes of the concentration and the composition result in the change in the permeation characteristics of hydrogen isotopes.

Dynamical evolution of CO2 and H2O on garnet electrolyte elucidated by ambient pressure X-ray spectroscopies

Garnet-type Li6.5La3Zr1.5Ta0.5O12 (LLZO) is considered a promising solid electrolyte, but the surface degradation in air hinders its application for all-solid-state battery. Recent studies have mainly focused on the final products of the LLZO surface reactions due to lacking of powerful in situ characterization methods. Here, we use ambient pressure X-ray spectroscopies to in situ investigate the dynamical evolution of LLZO surface in different gas environments. The newly developed ambient pressure mapping of resonant Auger spectroscopy clearly distinguishes the lithium containing species, including LiOH, Li2O, Li2CO3 and lattice oxygen. The reaction of CO2 with LLZO to form Li2CO3 is found to be a thermodynamically favored self-limiting reaction. On the contrary, the reaction of H2O with LLZO lags behind that of CO2, but intensifies at high pressure. More interestingly, the results provide direct spectroscopic evidence for the existence of Li+/H+ exchange and reveal the importance of the initial layer formed on clean electrolyte surface in determining their air stability. This work demonstrates that the newly developed in situ technologies pave a new way to investigate the oxygen evolution and surface degradation mechanism in energy materials.

Comparative study of titanium and chromium transition layers on quartz substrates

As an important functional material, quartz needs to be firmly welded with electrodes through a transition layer—such as a Ti or Cr film—for practical applications. It is important to understand the microstructure of the transition layer and its interfacial structure with quartz to improve the reliability of corresponding devices. The present authors conducted a systematic comparative study on Ti and Cr thin films deposited on the surface of quartz. The distribution and valence of elements on the film–substrate interface were analyzed by X-ray photoelectron spectroscopy. The grain size and defect distribution in the films, as well as the morphology and composition distribution at the film–substrate interface, were characterized by transmission electron microscopy in combination with energy-dispersive spectrometry. The phase and preferred orientation of the films were measured by X-ray diffraction. The bonding force between the Ti and Cr films and quartz was investigated through nanoscratch experiments. Fracture analysis of the delaminated films was carried out by Auger electron spectrometry. Substantial chemical bonding was generated at the Ti–quartz interface, and there were no detectable micro-defects, resulting in high bonding strength. During deposition of the Cr film, there was substantial atomic peening, resulting in a nanoscale damage layer on the surface of quartz, facilitating delamination in scratch experiments.

Stability investigation of Eu3+ doped CaF2 thin film with ZnO coating under electron beam irradiation

Eu3+ ion doped CaF2 thin film was successfully prepared using the hydrothermal method and coated by a spin coating technique. A thin layer of ZnO was deposited on the Eu3+ doped CaF2 thin film by pulsed laser technique. Incorporation of the dopant into the CaF2 crystal was confirmed by x-ray powder diffraction and x-ray photoelectron spectroscopy (XPS). Excitation of the film at 227 nm produced the characteristic emissions of Eu3+ ions. The stability of the film under electron beam bombard was studied using Auger electron spectroscopy, cathodoluminescence (CL), and XPS. The CL and Auger peak-to-peak heights (APPHs) data were collected concurrently using the same electron beam. The APPH of Ca and O increased, while that of F decreased, which indicated the conversion of CaF2 to CaO. The CL emission decreased initially during degradation and stabilized beyond 48 C/cm2 for the film with the ZnO coating. XPS analysis also indicated the dissociation of the fluoride compounds and subsequent formation of oxide compounds such as CaO and EuO after electron beam degradation.

Preferential intergranular oxidation as a potential degradation mechanism for Alloy X-750 CANDU spacers

Oxidation experiments on Alloy X-750 were performed in reducing CO-CO2 mixtures to assess the possibility of preferential intergranular oxidation (PIO) in relation to CANDU garter-spring spacers. The testing environments simulate hypothetical off-chemistry scenarios, promoting the oxidation of the alloying elements, but not Ni. Surface and cross-section microscopy corroborated by Auger electron spectroscopy confirmed the occurrence of internal and intergranular oxidation in Alloy X-750, accompanied by Ni nodule expulsion to the surface. Results are qualitatively similar to observations in Alloy 600 exposed to 480°C hydrogenated steam, used as an accelerated environment for primary water stress corrosion cracking (PWSCC) testing.

Sol-gel derived SiOx:TiOy films for integrated optics: HR S/TEM and AES/XPS insight to structure and chemical composition

Comprehensive studies on SiOx:TiOy composite waveguide layers with a high refractive index (n = 1.8), synthesized through sol–gel and dip-coating techniques are presented. The layers' structural and microchemical properties are determined using methods with different spatial resolutions (nm/μm/mm) and information depths (surface/bulk): optical transmittance, ellipsometry, transmission electron microscopy, Raman spectroscopy, Auger electron spectroscopy combined with ion profiling, and X-ray photoelectron spectroscopy. In the SiOx:TiOy films, 5 nm). Different Si- and Ti-rich phase formation mechanisms linked to alkoxide oxidation rates are found. The film composition (x = 1.1, y = 2.1) and homogenous in-depth O, Ti, and Si concentration profiles were determined. The Si/(Ti + Si) = 0.5 matching the synthesis procedure, oxygen deficiency (O/(Ti + Si) = 1.66), and oxygen vacancies in the silica phase are observed, with AES/XPS chemical shifts providing insights into bonding configurations. The SiOx:TiOy structural/chemical properties correlate well with exceptional optical film features.

Laser temperature programmed desorption: A flexible technique to study ion-surface interaction.

Understanding the physical-chemical processes ruling the interaction of particles (atoms, molecules, and ions) with surfaces is fundamental in several research fields, such as heterogeneous catalysis, astrochemistry, and nuclear fusion. In particular, the interaction of hydrogen isotopes with plasma facing materials represents a high-priority research task in the fusion community. Such studies are essential to ensure the successful operation of experimental fusion reactors, such as the tokamak ITER. In this work, we present a surface science apparatus developed to study ion-surface interaction in fusion relevant systems. It combines laser-based techniques with contaminant-free ion/molecular beams, mass spectrometry, and surface science tools such as low-energy electron diffraction and Auger electron spectroscopy. It allows to cover a wide range of sample temperatures, from 130 to 2300K, by changing the heating rate of samples from 0.1 to 135 K/s and maintaining the linearity of the heating ramps, a powerful feature to gain insight on adsorption, absorption, and desorption mechanisms. Experimental calibration and performance are presented in detail. Moreover, to provide a factual overview of the experimental capabilities, we focus on two different applications: the protocol used to clean a W(110) single crystal sample and the development of laser temperature programmed desorption to study helium retention in tungsten.

Low power silicon evaporation source—Construction, performances, and applications

The construction of a low power silicon evaporation source for thin film deposition applications is proposed in this article. A few differently shaped tungsten filaments were mounted inside a quartz glass crucible, which assured an effective heating of silicon wafer pieces. The sublimation process was monitored at filament powers in the range of 8–22 W, which corresponds to temperatures far below the melting point of Si. The operation of the evaporation source requires only the use of a low voltage power supply. All considered models of evaporation sources are characterized by an easy construction. The measurements carried out with the use of a quartz crystal microbalance sensor enabled to determine the deposition rate at different filament powers for all constructed Si sources and confirm the long-term stability of the silicon flux. The experimental data exhibit the Polany–Wigner dependence of the deposition rate as a function of inverse of power at higher filament powers. Auger electron spectroscopy was used to monitor the deposition of Si on Ag(100) under constant silicon flux. The Auger signal recorded from Si and Ag reflects the growth of subsequent silicon layers. This enabled the determination of the Frank–van der Merwe growth mode of Si on Ag(100) at early stages of growth, the formation time of one Si monolayer, and, thus, the deposition rate. The presented designs of the Si source exhibit long time stable evaporation fully controlled by the applied filament power, which is crucial in the precise adsorption of ultrathin Si layers.

Quantification in high-energy resolution Auger electron spectroscopy; Proposal of a reference target convolution technique for direct spectra

Currently, high-energy resolution Auger electron spectroscopy (AES) is utilized for chemical-state qualitative analysis, such as x-ray photoelectron spectroscopy. It is highly desirable to perform quantitative analysis using the high-energy resolution direct spectra used for qualitative analysis. However, AES analysis parameters, such as relative sensitivity factors (RSFs), derived from conventional-energy resolution differentiated spectra cannot be adopted for high-energy resolution direct spectra. Furthermore, for quantification by high-energy resolution direct spectra, there is no established method for determining peak intensity, and no database of RSFs is available in surface analysis communities. Therefore, we tasked ourselves with investigating the use of the analysis parameters obtained from conventional-energy resolution-differentiated spectra obtained with a cylindrical mirror analyzer (CMA)-type AES instrument for high-energy resolution direct spectra measured with a spherical capacitor analyzer (SCA)-type AES instrument. The convolution technique proposed here is achieved by using a conventional-energy resolution spectral dataset obtained with CMA-AES as a target. By applying the convolution with the window function of the convoluted function of the Gaussian function and rectangular function, high-energy resolution direct spectra containing the inherent nature of fine structures are converted to the similar shapes of conventional-energy resolution direct spectra after the Shirley type background subtraction [Watanabe et al., J. Vac. Sci. Technol. A 41, 043209 (2023)]. Results revealed that for all spectra of conventional-energy resolution spectra taken with CMA-AES, as well as high-energy resolution spectra taken with SCA-AES with various energy resolutions, the ratios of the background-subtracted direct peak areas and the differentiated peak-to-peak intensities were well-aligned along the identical parabolic curve as a function of the kinetic energy (KE). Experimental results also revealed that the generalized conversion function f(KE;ΔE)=IareacmaIareaconv.sca(KE;ΔE), which is the ratio of the conventional-energy resolution spectral area (Iareacma) and the convoluted high-energy resolution spectral area (Iareaconv.sca), which can transform differentiated intensities of convoluted high-energy resolution spectra, such that they are similar to those of conventional-energy resolution spectra obtained using the CMA-AES instrument, being a function of KE and the energy resolution ΔE. By applying the conversion function, the historically accumulated AES analysis parameters for conventional-energy resolution differentiated spectra can be adopted to differentiated high-energy resolution spectra. Finally, the results revealed the sufficiency of the conversion function obtained by the actual measurements of the four reference specimens for the practical quantification of high-energy resolution AES direct spectra.

Electrochemical degradation of the hydrogen-absorption-induced passive film on an Ni–Ti superelastic alloy in an NaCl solution

This study was conducted to investigate the effects of electrochemically generated hydrogen on the passivation behaviour of Ni–Ti alloy surfaces. Hydrogen charging via galvanostatic polarisation increased the passive current density during cyclic potentiodynamic polarisation experiments. Electrochemical impedance spectroscopy and Mott–Schottky analyses revealed an increase in the electrochemical conductivity of the film, indicating that hydrogen charging increased the donor density. Changes in the compositions were detected by Auger electron spectroscopy and X-ray photoelectron spectroscopy. Scanning transmission electron microscopy revealed film degradation after hydrogen charging. These results demonstrate that the electrochemical conductivity of the passive film increased owing to hydrogen absorption.

Acid Treatments of Ti-Based Metallic Glasses for Improving Corrosion Resistance in Implant Applications

Ti-based bulk metallic glasses are promising materials for metallic bone implants, mainly due to their mechanical biofunctionality. A major drawback is their limited corrosion resistance, with high sensitivity to pitting. Thus, effective surface treatments for these alloys must be developed. This work investigates the electrochemical treatment feasibility of nitric acid (HNO3) solution for two bulk glass-forming alloys. The surface states obtained at different anodic potentials are characterized with electron microscopy and Auger electron spectroscopy. The corrosion behavior of the treated glassy alloys is analyzed via comparison to non-treated states in phosphate-buffered saline solution (PBS) at 37 °C. For the glassy Ti47Zr7.5Cu38Fe2.5Sn2Si1Ag2 alloy, the pre-treatment causes pseudo-dealloying, with a transformation from naturally passivated surfaces to Ti- and Zr-oxide nanoporous layers and Cu-species removal from the near-surface regions. This results in effective suppression of chloride-induced pitting in PBS. The glassy Ti40Zr10Cu34Pd14Sn2 alloy shows lower free corrosion activity in HNO3 and PBS due to Pd stabilizing its strong passivity. However, this alloy undergoes pitting under anodic conditions. Surface pre-treatment results in Cu depletion but causes enrichment of Pd species and non-homogeneous surface oxidation. Therefore, for this glassy alloy, pitting cannot be completely inhibited in PBS. Concluding, anodic treatments in HNO3 are more suitable for Pd-free glassy Ti-based alloys.

Growth of MnxAu1−x Films on Cu(001) and Ag(001) Single‐Crystal Substrates

The growth, morphology, and structure of films on Cu(001) and Ag(001) are studied by means of low‐energy electron diffraction (LEED), medium‐energy electron diffraction, Auger electron spectroscopy, and scanning tunnelling microscopy. Different concentrations x from about 0.5 to 1 and thicknesses from 0.2 to 12.9 ML of are examined. For several values of x, exhibits a c(2 2) superstructure pattern on Cu(001) when the total thickness is around or above 0.5 ML. Above 1 ML, LEED patterns of can be only observed on Ag(001), but not on Cu(001). LEED‐I(V) is employed to deduce the vertical interlayer distance for as‐grown and post‐annealed films on Ag(001). Above 500 K, Ag from the substrate segregates into the films.

Passive Film Formed on Si-Mn Steel in Boric Acid-Borate Buffer at 6.5

Passivity-maintaining current of high-strength (Si-Mn) steel in boric acid-borate buffer at pH 6.5 was larger than that of ferrite/pearlite (F/P) steel. Charge transfer resistance of the Si-Mn steel surface passivated at 1.10 V vs SHE in pH 6.5 buffer was smaller than that of F/P steel surface. Nano-analyses using AES and STEM revealed the details of the structure and components of the passive film on the Si-Mn steel. The inferiorities of passivity of Si-Mn steel were suggested to be due to the alloying components and metallurgical structure to increase the strength of the steel.

Co-deposition of bismuth-nitrogen films on MgO (001) by molecular beam epitaxy

We attempted to grow a thin film of BiN by co-deposition of bismuth and nitrogen on rock-salt structure MgO (001) substrates. Furthermore, we studied the effect of variation of the growth temperature and the nitrogen to bismuth flux ratios on sample growth. For the samples grown and conditions used, we do not find strong evidence for the formation of a bulk Bi-N alloy. Even for very high nitrogen to bismuth flux ratio, we observed only bismuth and no nitrogen using bulk Rutherford back-scattering spectroscopy measurements, and only 1%–2% nitrogen was seen through surface Auger electron spectroscopy measurements. The in-plane lattice measurements show that the resulting Bi (110) samples are strained, which is presumably caused by lattice mismatch between the sample and the substrate when grown without any buffer layer. The use of a high-temperature buffer layer helps to release strain in the sample but only along one axis. Measurements of the atomic layer spacing using x-ray diffraction and also scanning tunneling microscopy confirm the Bi (110) thin film sample structure.