Oxygen Impurities Research Articles

Improvement of superconducting, morphological, and flux pinning ability of YBa2Cu3O7−y matrix with oxygen and Mn2O3 impurity

Abstract In the current work, the influence of oxygen and Mn2O3 impurity levels intervals 0.00 ≤ x ≤ 0.30 on various key properties such as electrical resistivity, superconducting, flux pinning ability, stabilization of ceramic system, and morphological properties of YBa2Cu3O7-y (Y-123) superconductor were examined by electrical resistivity, critical current density, and scanning electron microscopy (SEM), electron dispersive x-ray (EDX) measurements. The EDX test results indicated that all the Y-123 ceramics produced possessed different composition distributions on the sample surface. SEM photomicrographs also confirmed the improvement in the appearance of surface morphology and crystallinity quality of the YBa2Cu3O7-y system. Moreover, the development in the interaction quality between grains, pinning ability and strength quality of 2D coupled vortices was obtained with the oxygen ambient and optimum manganese impurity addition highly dispersing throughout the intra grain and inter-grain boundary couplings due to the increase in the artificial flux pinning nucleation sites in the Y-123 system. Thus, the best sample with the highest Jc value of 98 A/cm2 showed the most resistance to the applied magnetic field and current. Similarly, the same sample exhibited the greatest superconductive offset (98.320 K) and onset (100.504 K) temperatures values based on the development of the Cu-O coordination and stability of the crystal structure. In conclusion, this comprehensive study based on the analysis of oxygen and Mn2O3 impurity addition mechanism through the YBa2Cu3O7-y ceramic matrix may open a new and applicable field for advanced engineering, heavy industry technology and large-scale applications.

Deoxidation of Titanium Utilizing Thulium and Halide Flux

AbstractDevelopment of an efficient deoxidation method for titanium (Ti) is desired to recycle oxygen (O)-contaminated Ti scrap. In this study, the utilization of thulium (Tm) as a deoxidant for Ti in various halide fluxes was investigated. Tm is a rare-earth metal, which is a by-product of other rare-earth metals with high demand and has limited industrial uses. When NaCl or KCl flux was installed in the deoxidation experiments, the impurity oxygen in Ti was removed to the concentrations of 140–590 mass ppm O, which are lower than that achieved under the equilibrium between Tm and Tm2O3 (290–530 mass ppm O). The results show that the nominal activity of the deoxidation product (Tm2O3) was lowered by the presence of halide fluxes in the reaction systems. The combination of Tm and halide fluxes in a new deoxidation technique holds promising potential for both accelerating the Ti recycling and exploring novel applications for Tm. Graphical Abstract

Optimization of chemical engineering control for large-scale alkaline electrolysis systems based on renewable energy sources

In the context of renewable energy, dynamic control is crucial for large-scale alkaline water electrolysis systems. Under traditional Proportional-Integral-Derivative (PID) control, the system's temperature and impurity levels may exceed safe limits during sudden load changes, compromising system safety. Therefore, this study proposes a control strategy based on mathematical models of system temperature and impurities, including Model Predictive Control (MPC) for temperature and Optimal Curve Tracking (OCT) for impurities. The MPC controller offsets the disturbances in temperature caused by current fluctuations through state prediction, while the OCT controller ensures that impurity levels remain within safe limits. Real-time application of these control strategies is achieved through MATLAB-PLC communication, validating controller performance. Experimental results show that the MPC controller exhibits excellent dynamic response and stability in controlling the stack temperature, with a maximum temperature peak deviation of only 2.9 K and a temperature fluctuation range of 5.9 K. This represents a reduction of 1.6 K in peak deviation compared to traditional PID controllers and significantly decreases the temperature fluctuation range. The OCT controller also demonstrates good safety and stability in controlling hydrogen to oxygen (HTO) impurity levels, consistently maintaining the HTO content at the set upper limit of 1.5%, thereby expanding the safe operational range of the system and reducing the need for frequent adjustments to the system setpoints.

Study of spectral features and depth distributions of boron layers on tungsten substrates by ps-LIBS in a vacuum environment

Boronization is used in present-devices as wall condition technique due to its effectiveness in reducing oxygen and other impurities in the vessel as well as improving plasma performance. The technique is also currently under consideration as wall conditioning method for the proposed full-tungsten (W) wall of the International Thermonuclear Experimental Reactor (ITER). However, the impact of the deposited Boron (B) layer thickness, and its homogeneity after the boronization process is uncertain as well as knowledge about the layer lifetime and improved conditions. In this study, an approach of the picosecond-laser-induced breakdown spectroscopy (ps-LIBS) is investigated to analyze the depth distribution of B-films on W-substrates by using three optical spectrometers in a vacuum environment. The depth distribution of two types of B-films on W-substrates with the thicknesses of 130 nm and 260 nm were sequentially measured under different laser spot sizes (varying the laser fluence). The B-films on the W-substrates were made by magnetron sputtering to simulate the thin B layers during the boronization. The measured average ablation rate of ps-LIBS shows a notable decrease with increasing laser spot size. Additionally, the spectral lines of B and W exhibit distinct intensity distributions under different spot sizes due to the different excitation thresholds of the B-films and the W-substrates. The interface between B-films and W-substrates, as well as the thickness of the B-films, were determined using the normalized intensity and intensity ratio method, respectively. The results from ps-LIBS measurements regarding the depth are in good agreement with those obtained through the Focused Ion Beam combined with Scanning Electron Microscopy (FIB-SEM) and Energy Dispersive X-ray Spectroscopy (EDS). These initial findings verify the feasibility to characterize the thickness and uniformity of thin B films in the order of 100 nm and below on W-substrates using ps-LIBS.

Influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr

We report the influence of oxygen impurities in generating ferromagnetism in GaN doped with Mn, Fe, and Cr through superexchange involving Mn–O–Mn, Fe–O–Fe, and Cr–N–Cr atomic configurations. Density Functional Theory (DFT) calculations demonstrated that these configurations originate within VGa-ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}-{O}_{\ ext{N}}$$\\end{document} complex defects by incorporating Mn2+, Fe2+, and Cr3+ ions into gallium vacancies (VGa\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}$$\\end{document}) sites promoted by the presence of oxygen as a substitutional impurity (ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${O}_{\ ext{N}}$$\\end{document}). These co-doped GaN microstructures were synthesized using the thermal evaporation method. Cathodoluminescence (CL) and photoluminescence (PL) measurements confirmed the presence of VGa-ON\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${V}_{\ ext{Ga}}-{O}_{\ ext{N}}$$\\end{document} complex defects in all GaN-grown samples. X-ray photoelectron spectroscopy (XPS) measurements confirmed the successful incorporation of Mn2+, Fe2+, and Cr3+ ions in GaN samples. SQUID measurements demonstrated room-temperature ferromagnetism with respective saturation magnetization (Ms) and coercive field (Hc) values of ± 1.5 × 10−5 emu and 4 mT for GaN:O,Mn, ± 4.4 × 10−5 emu and 2.6 mT for GaN:O,Fe, and ± 1.7 × 10−5 emu and 2.6 mT for GaN:O,Cr.

Towards High-Quality Investment Casting of Ti-6Al-4V with Novel Calcium Zirconate Crucibles and Optimized Process Control

The investment casting of titanium and its alloys relies on a high resistance of the crucibles and shell molds in terms of temperature and reactivity. The availability of ceramic crucibles that offer sufficient resistance to the titanium melt enables vacuum induction melting (VIM). CaZrO3 prepared from a mixture of CaO and ZrO2 as a raw material for refractory ceramics shows a high corrosion resistance against metallic melts even under very high temperatures up to 1800 °C. Crucibles and shell molds of CaZrO3 were successfully produced and used in subsequent casting trials. This study is focused on the refractory crucibles suitable for casting Ti-6Al-4V (Ti-64) using a tilt casting machine. In order to evaluate the crucible reaction and, therefore, the quality of the castings, chemical analyses, investigations of the microstructures and hardness measurements were carried out. Careful control of the melting duration is mandatory to avoid crucible reactions that otherwise result in contamination of the cast with oxygen and zirconium. This was achieved by modified coil geometries. Under optimized casting conditions, the oxygen and zirconium impurity limits of ASTM B367-09 for titanium castings were met. Based on the correlations found, optimized casting parameters with regard to material quantity, coil geometry and heating power could be determined in order to provide guidance for a high-quality casting process with VIM.

Calculation of oxygen distribution coefficients of RF3 (R = La, Gd) fluorides with the tysonite structure during their crystallization from a melt

Using the method of modified cryoscopy, the thermodynamic distribution coefficients of oxygen k0 in LaF3 and α-GdF3 with a tysonite structure (sp. gr. )were calculated from the fusibility diagrams of condensed systems RF3–R2O3 (R = La, Gd). The calculated coefficients k0 are 1.02 and 1.12 for lanthanum and gadolinium trifluorides, respectively. The values of the coefficients k0 satisfy the condition k0 1, which confirms the formation of maxima in the fusibility curves of tysonite solid solutions tys- RF3–2xOx. For LaF3, the proximity of the distribution coefficient to k0 = 1 corresponds to an almost uniform distribution of oxygen in the volume of the crystallized fluoride melt. Knowledge of oxygen distribution coefficients during crystallization from a melt is important for choosing a strategy for crystallophysical purification of trifluorides RF3 from oxygen impurities and obtaining oxofluorides tys-RF3–2xOx with a given impurity distribution.

Observation of terahertz nonlinear absorption activity in Al2O3

We investigate the terahertz (THz) nonlinear absorption characteristics in a thin Al2O3 crystal using nonlinear THz spectroscopy. A THz saturable absorption performance with a high modulation depth (27.5%) and a relatively low saturable intensity (6.99 µJ/cm2) of Al2O3 is revealed, covering the THz spectrum from 0.1 to 8 THz. The inevitable presence of oxygen vacancies and impurities in Al2O3 single crystal results in the existence of free electrons within the conduction band. The transmission enhancement can be described by the change of the mobility of electrons due to intervalley scattering induced by THz pulses, based on first-principles calculations. Therefore, Al2O3 crystals have promising application potential in mode-locked devices for directly delivering broadband ultrashort THz pulses.

Laser powder bed fusion in-situ alloying of W-Y alloy: Microstructure, mechanical properties and cracking suppression

The microcracks caused by impurity oxygen are recognized as one of the main challenges in additive manufacturing of tungsten. In this study, yttrium was incorporated into the tungsten matrix to suppress crack formation, and W-Y alloys with minimal cracks were successfully obtained by laser powder bed fusion (LPBF). It is found that during the LPBF process, yttrium combines with impurity oxygen to generate intergranular and intragranular precipitated particles in situ, which effectively suppress cracking behavior due to impurity oxygen. Furthermore, these intracrystalline nanoprecipitate are cubic Y2O3 particles that have formed a semi-coherent interface with the tungsten matrix. These dispersed particles significantly improved the mechanical properties of W-Y alloy. The results offer a corresponding strategy for crack suppression of tungsten alloys in laser additive manufacturing processes, and would provide a benificial additive manufacturing strategy to other refractory alloys.

Development of an automated system for the purification of alkanolamine solutions

The alkanolamine solutions used in natural gas purification processes are inevitably degraded over time. This occurs due to accumulation of reaction products from the reactions with carbon dioxide, hydrogen sulphide, oxygen and other impurities present in the gas streams, as well as from thermal degradation. The degradation of solutions leads to the formation of thermostable compounds that not only reduce absorption efficiency, but also increase corrosive activity. Furthermore, part of the amine turns into a bound state and becomes ballast. The necessity of purification of alkanolamine solutions is becoming more and more urgent since the cost of maintaining efficient operation of gas treatment plants grows, and environmental safety requirements increase. Purification of solutions makes it possible to prolong their service life, reduce the cost of purchasing new reagents and reduce the negative impact on the equipment. In this work the method of anion-exchange technology of purification is used. Unlike vacuum distillation and electrodialysis, the considered technology does not require significant energy costs for generation and maintenance of vacuum, and heating of solutions, it can be easily integrated into the existing production process without any significant changes in the infrastructure. The described problem is relevant for Kazakhstan oil refineries, two of which use methyldiethanolamine, and one of which uses diethanolamine, and the existing practice of maintaining the operability of the systems is based on periodic replacement of part of the solution with pure amine. The development of automated systems for purification of such solutions makes it possible to significantly improve process control, minimise manual labour, and improve the overall economic efficiency of production.

Uncovering the Intrinsic High Fracture Toughness of Titanium via Lowered Oxygen Impurity Content.

Titanium (Ti) and its alloys are known to exhibit room-temperature fracture toughness below 130 MPa m1/2, only about one half of the best austenitic stainless steels. It is purported that this is not the best possible fracture resistance of Ti, but a result of oxygen impurities that sensitively retard the activities of plasticity carriers in this hexagonal close-packed metal. By a reduction of oxygen content from the 0.14wt% in commercial purity Ti to 0.02wt%, the mode-Ι fracture toughness of the low-oxygen Ti is measured to be as high as KJ Ic ≈ 255 MPa m1/2, corresponding to J-integral-based crack-initiation toughness of up to JIc ≈ 537kJ m-2. This extraordinary toughness, reported here for the first time for pure Ti, places Ti among the toughest known materials. The intrinsic high fracture resistance is attributed to the profuse plastic deformation in a significantly enlarged plastic zone, rendered by the pronounced deformation twinning ahead of the crack tip along with ample twin-stimulated 〈c+a〉 dislocation activities, in the absence of impeding oxygen. Controlling the content of a property-controlling impurity thus holds the promise to be a readily applicable strategy to reach for unprecedented damage tolerance in some other structural alloys.

Preparation, characterization and biological activity of Co-doped ZnO nanostructured thin film: A comprehensive study on its photo-physical properties and antimicrobial efficacy against food-borne pathogen

The Co@ZnO thin film deposited on glass substrate with dopant contents of cobalt ranging from 0 to 10 % were fabricated using spray pyrolysis coating method. The prepared nanocomposite thin film was characterized by scanning electron microscopy, X-ray diffraction, UV–vis and Raman spectroscopy. Some surfaces structural probing of the deposited samples confirmed nanolamination of hexagonal wurtzite phase of ZnO with no other impurity phases and high adherence on the soda lime glass substrate. Average grain sizes (56–43 nm) and lattice strain of the films were found to be tailored with the variation of Co-dopant content, signifying phonon confinement or defect/disorder caused by the Co-dopant impurity on the ZnO host particle owing to the impurity levels and oxygen vacancy states. The film demonstrated high optical transmittance with enhanced photoabsorbtion and narrow optical band gap (3.24–2.64 eV) with increasing Co-dopant content. In evaluating its antibacterial efficacy, the Co@ZnO thin film was tested at different dopant concentration against Bacillus cereus (foodborne pathogen). The result revealed that the films exhibits excellent inhibitory effect on the pathogen, with highest activity obtained at 10 % Co@ZnO. Furthermore, a more improved inhibitory activity was recorded when at 10 % Co@ZnO dopant was exposed to UV irradiation.

Phase formation, microstructure and mechanical properties of TaB2–SiC composites synthesized by reaction hot pressing: Effects of SiC contents and oxygen impurity

TaB2–SiC composites with 0–20 wt% SiC contents were prepared by reaction hot pressing using Ta, B and SiC powders as starting materials. Densification, constituent phases, microstructure and mechanical properties, namely Vickers hardness, fracture toughness and flexure strength, were evaluated by means of inspection of sintering shrinkage, density measurement, XRD, SEM, TEM, HRTEM, EDS, SAED, indentation and three-point bending tests. Phase formation, including dominant (TaB2, SiC) and minor (TaC, glassy SiO2) phases, was checked by thermodynamic assessment relevant with Ta2O5 and B2O3 impurities introduced into the reaction system by the starting powders. The results showed that mixtures of Ta, B and SiC powders would initiate self-propagating combustion synthesis (SPCS) at about 900 °C; a transient hold at 800 °C for 1 h could suppress this reaction. Volatilization of B2O3 impurity in association with local high temperature due to SPCS helped reduce the TaC and glassy SiO2 minor phase formation. TaB2–SiC composites could reach 99 % relative densities with 3 wt% SiC addition and above. Compositions with <7.5 wt% SiC additions showed uniform dispersion of SiC particles at multi-TaB2 grain junctions while compositions with higher SiC content revealed SiC segregation. Bending strength of 503 MPa and fracture toughness of 6.69 MPa⋅m1/2 could be reached with 7.5–20 wt% SiC addition.

Effects of YH2 dopant on densification behavior, microstructure and mechanical properties of Ti–6Al–4V alloys

Ti6Al4V-xYH2 (x = 0, 0.1, 0.2, and 0.3 wt%) was produced in this research employing conventional powder metallurgy methods (cold pressing and sintering). The densification behavior, microstructure and mechanical properties of Ti6Al4V alloy caused by the addition of YH2 were systematically studied. The outcomes indicated that the Ti6Al4V containing 0.1 wt% YH2 has received a synergistic increase in ductility and strength (Ultimate tensile strength: 976.4 MPa; Elongation: 9.3 %), which is mainly attributable to the combined effect of grain refinement and purification of impurity oxygen. The study provides an economical approach for employing low-cost, high-oxygen HDH Ti powder to produce high-performance Ti material.

Microstructure, Mechanical and Tribological Properties of Cu40Zn-Ti3AlC2 Composites by Powder Metallurgy

The exploration of unleaded free-cutting Cu40Zn brass with excellent mechanical and tribological properties has always drawn the attention of researchers. Due to its attractive properties combining metals and ceramics, Ti3AlC2 was added to Cu40Zn brass using high-energy milling and hot-pressing sintering. The effects of Ti3AlC2 on the microstructure, mechanical and tribological properties of Cu40Zn-Ti3AlC2 composites were studied. The results showed that Ti3AlC2 could suppress the formation of ZnO by adsorbing oxygen impurity and promote the formation of the β phase by releasing the β-forming element Al to the substrate. The hardness and wear resistance of Cu40Zn-Ti3AlC2 composites increased with increasing Ti3AlC2 content from 0 to 5 wt.%. The proper Ti3AlC2 additive was beneficial to both the strength and plasticity of the composites. The underlying mechanisms were discussed.

Characterization of Growth Sectors in Gallium Nitride Substrate Wafers

During crystal growth processes, growth sectors are formed due to growth along different crystallographic directions. Although the crystal structure in the different growth sectors is unchanged, strain induced topography contrast is observed by synchrotron X-ray topography. In this study, synchrotron monochromatic beam X-ray topography (SMBXT), synchrotron X-ray plane wave topography (SXPWT), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and secondary ion mass spectrometry (SIMS) are used to characterize growth sectors in gallium nitride (GaN) substrate wafers grown by patterned hydride vapor phase epitaxy (HVPE). The SMBXT images reveal the boundaries of {0001} and {1122} type growth sectors. Strain maps generated from SXPWT shows that the out-of-plane strains in different growth sectors have a difference of the order of 10-5. SEM images from SE2 signal shows no contrast of growth sector boundaries while images from Robinson detector (RBSD) show different growth sectors as different grey scale contrast, indicating a strain effect. SIMS analysis shows that the different oxygen impurity levels in the growth sectors, which is the origin of the strain. A formation mechanism of growth sectors in patterned HVPE grown GaN wafers is proposed.

Spark plasma sintering of TiC with TiAly as sintering aid: Mechanisms and microstructures

TiC features an interesting combination of mechanical properties, high-temperature resistance, and lightness, making it an excellent candidate for several applications in harsh environments. However, its sintering to obtain bulk components is extremely challenging. Herein, we show that titanium aluminide is a promising sintering aid for TiC (5, 10, and 20 vol% were investigated). The aluminide allows the formation of a nearly fully dense component at 1350 °C by spark plasma sintering under 80 MPa. The aluminide forms a grain boundary secondary phase that promotes the Ti diffusion: Ti from TiC can be dissolved within the TiAly at the neck center and precipitate at the neck surface, while C can easily diffuse through the TiC lattice. Higher temperatures cause the extrusion of the aluminide out of the SPS die and its reaction with oxygen impurities. The final microstructure is constituted by nearly pure TiC with isolated alumina pockets at the triple points.

Enhanced broadband infrared radiation from rare earth orthochromites for High-Temperature radiative heat transfer

The development of broadband, high-performance infrared radiation materials is crucial for energy conservation and applications in aerospace and industrial sectors. Rare earth orthochromites, such as PrCrO3, exhibit good thermal stability and high infrared emissivity beyond the 6 μm wavelength range. However, their large bandgap limits their infrared emissivity before 6 μm, significantly impacting their potential applications. Herein, we have successfully enhanced the thermal emissivity of PrCrO3 by manipulating oxygen vacancies (OV) and accompanying impurity levels, leading to the synthesis of five rare earth orthochromites. Compared with pristine PrCrO3, co-doping of Ca, Co, and Mn introduced oxygen vacancies (OV) and impurity energy levels, effectively reducing the band gap and improving emissivity in the wavelengths below 6 μm. In particular, the infrared emissivity of (Pr0.3Y0.3Ca0.4)CrO3 in the wavelengths of 0.78–2.5 μm reaches 0.89, which is double than that of pristine PrCrO3. Furthermore, its thermal stability is excellent, as demonstrated by thermal shock experiments at 1500 ℃ for five cycles. More importantly, the developed orthochromites can be applied as a coating on substrates such as alumina ceramic sheets, exhibiting an average infrared emissivity of 0.95 and remarkable radiative heat transfer capability. This research contributes to the advancement of high-performance infrared radiation materials by vacancy engineering.

Control polarity of gallium nitride on Si (1 1 1) using atomic layer annealing and thermal atomic layer deposition

Ga-polar GaN thin films and N-polar GaN thin films were fabricated by using thermal ALD and plasma assisted ALA processes, respectively. The polarity of GaN wurtzite thin films was determined by cross-sectional STEM analysis of as-deposited films and top-view SEM images after KOH wet-etching. The crystallinity and grain size of thermal ALD GaN were drastically increased with the GaN ALA buffer layer. The ALA Ar plasma pulse in each ALD cycle decreased the oxygen and carbon impurity content and improved the crystallinity of GaN thin films by removing organic ligands. High purity GaN thin films were successfully deposited on oxide-free Si (111) substrate by using the ALA process with 100 ms of TDMAGa with push gas, 3 × 800 ms of N2H4, and 15 s of 25 W ALA plasma pulse with −25 V stage DC bias at 275 °C. The lowest FWHM value (0.59°), smooth surface morphology (RMS=1.0 nm), and 10–20 nm grain size of columnar GaN thin films were obtained by tuning process parameters.

Multi-physics modeling of tungsten collector probe samples during the WEST C4 He campaign

We describe the results of a multi-scale, multi-physics modeling assessment of SOLPS-ITER, hPIC2, RustBCA and Xolotl, in which five single-crystal tungsten (W) samples were placed in a reciprocating collector probe and exposed to helium (He) plasma in the WEST fusion device. In our models, we considered a pure (100 %) He plasma, as well as one with oxygen (O) present (95% He 5% O) corresponding to the impurity concentration estimated during the C4 He campaign in WEST. Our SOLPS simulations approximately match experimental reciprocating Langmuir probe plasma measurements of plasma density and temperature. Using these plasma parameters as input, hPIC2 and RustBCA predict that the presence of oxygen impurities lead to a 15%–20% decrease in ion and heat fluxes to the surface, and an order of magnitude higher sputtering yields (compared with a pure He plasma). Xolotl predictions for the response of tungsten to plasma surface interactions (PSIs) agree with experimental LAMS analysis, and indicate large near-surface He concentrations, which quickly decay with depth. Our model also shows an increasing role of erosion—in removing the near-surface He—with time. Overall, slightly higher retention is predicted for tungsten exposed to a pure He plasma, with the largest differences in the near-surface gas content caused by the large oxygen-induced erosion. This highlights the important role that impurities play in PSI. Therefore, future work will focus on providing a fully self-consistent description of oxygen (and oxides, etc.) in our models, through multi-species implementation in GITR and inclusion of oxygen and tungsten oxide formation in Xolotl.