Vacuum最新文献

{"title":"An easily overlooked aspect of hydrothermal charcoal: The effect of drying method on structure and properties","authors":"Qingdan Liao ,&nbsp;Dahua Yu ,&nbsp;Xitong Li ,&nbsp;Jingxin Huang","doi":"10.1016/j.vacuum.2025.114471","DOIUrl":"10.1016/j.vacuum.2025.114471","url":null,"abstract":"<div><div>Hydrothermal carbon (HC) demonstrates significant potential in heavy metal removal due to its low production cost and high adsorption efficiency. However, the impact of drying methods on HC performance is often overlooked. This study employed six types of agricultural waste as precursors to prepare HC using four different drying methods and evaluated their performance through Cd²⁺ adsorption experiments. Compared to natural drying, vacuum high temperature oven drying significantly increased the C-O functional group content by 25.29 %, optimized the pore structure, thereby enhancing the specific surface area and promoting mass transfer, diffusion, and adsorption behavior. In contrast, high temperature oven drying had a lesser degree of damage to the pore structure, while vacuum freeze drying led to the collapse of pores due to mechanical forces during ice crystal formation and sublimation, reducing the specific surface area to 2.15 m²/g. Additionally, the study comprehensively investigated other mechanisms such as complexation, co-precipitation, kinetics, and theoretical calculations. The practicality of this HC was assessed through seven cycles of adsorption-desorption. This study provides important scientific basis for the application of hydrothermal carbon in heavy metal removal, emphasizes the key role of drying methods, and points to a more energy-saving and environmentally friendly realization path.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114471"},"PeriodicalIF":3.8,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the quality of MOCVD-Grown α-Ga2O3 by introducing an AGO buffer on m-plane sapphire","authors":"Zhucheng Li ,&nbsp;Xiaodong Zhang ,&nbsp;Li Zhang ,&nbsp;Tiwei Chen ,&nbsp;Gaofu Guo ,&nbsp;Dengrui Zhao ,&nbsp;Yu Hu ,&nbsp;Zhili Zou ,&nbsp;Guangyuan Yu ,&nbsp;Wenxiang Mu ,&nbsp;Zhongming Zeng ,&nbsp;Baoshun Zhang","doi":"10.1016/j.vacuum.2025.114445","DOIUrl":"10.1016/j.vacuum.2025.114445","url":null,"abstract":"<div><div>α-gallium oxide has great potential in the power electronics field due to its high Baliga FOM(BFOM), however, the inferior quality of the epitaxial material limits the development of corresponding applications. This study investigates the morphology and behavior of dislocations in <em>α</em>-Ga₂O₃ films and considerably improves both the surface morphology and crystal quality of the films by inserting an (Al_xGa_1-x)₂O₃ buffer. Results reveal that the dislocations within the buffer lead to an overall tilt (0.5°) of the epitaxial layer relative to the substrate during the relaxation of mismatch stress. Furthermore, high-density screw dislocations propagate to the surface when the film reaches a certain thickness, becoming nucleation sites of <em>β</em>-Ga₂O₃ and formation of hillocks which severely damaged the surface quality of the film. But these hillocks on the buffer layer act as barriers to promote lateral growth of the <em>α</em>-Ga₂O₃ film, making dislocations bend and annihilate. By adjusting the morphology of the buffer, high quality <em>α</em>-Ga₂O₃ film is grown with the full width at half maximum (FWHM) of the (30-30) rocking curve decreased from 0.46° to 0.26°, and the surface roughness <strong>is</strong> reduced from 15.1 nm to 2.45 nm. This work demonstrates the excellent capability of MOCVD in growing high-quality <em>α</em>-Ga₂O₃ films.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114445"},"PeriodicalIF":3.8,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laser processing of lunar regolith simulants for beneficiation and metal extraction","authors":"Lucas-Brian Christen ,&nbsp;Masataka Watanabe ,&nbsp;Hiroto Yamakami ,&nbsp;Hokuto Sekine ,&nbsp;Kimiya Komurasaki ,&nbsp;Ai Momozawa ,&nbsp;Hiroyuki Koizumi","doi":"10.1016/j.vacuum.2025.114417","DOIUrl":"10.1016/j.vacuum.2025.114417","url":null,"abstract":"<div><div>In-situ resource utilization (ISRU) is a key aspect to establish a sustainable station on the Moon. Nevertheless, the extraction of metals from lunar regolith is lacking research often shadowed by the extraction of oxygen. In this study, laser ablation as a method for beneficiation with the potential for direct thermal reduction of regolith for metal extraction is introduced and demonstrated. Sintered samples of simulants EAC-1A, FJS-1, and JSC-2A are irradiated by a continuous-wave fiber laser with an intensity of 76<!--> <!-->MW<!--> <!-->m^-2 at an output power of 1.5<!--> <!-->kW in an Ar atmosphere at 1<!--> <!-->bar. The emission spectrum shows the presence of atomic K and Na, hence proving successful thermal reduction and metal extraction. Furthermore, an SEM/EDX analysis of the collection plate to which the extracted species adhered proves the extraction of P, K, Fe, Na, Si, and O. During laser ablation, the surface temperature was measured and a maximum of 2823<!--> <!-->K was identified. The surface temperature is in accordance with the boiling points of the oxides P₂O₅, K₂O, Na₂O, and SiO₂, suggesting the selective extraction of oxides from regolith according to their boiling points. Hence a multi-stage laser process for selective oxide extraction and beneficiation is suggested.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114417"},"PeriodicalIF":3.8,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144262214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of sputtering power on low concentration impurities in binary oxides: A ToF-ERDA characterization study","authors":"Filip Ferenčík ,&nbsp;Jozef Dobrovodský ,&nbsp;Edmund Dobročka ,&nbsp;Pavol Noga","doi":"10.1016/j.vacuum.2025.114418","DOIUrl":"10.1016/j.vacuum.2025.114418","url":null,"abstract":"","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114418"},"PeriodicalIF":3.8,"publicationDate":"2025-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined plasma diagnostic approaches for characterization of pulsed-DC driven hollow cathode discharge in a metal tube based on current-voltage characteristics, Langmuir probe, and optical emission spectroscopy","authors":"Dezhi Xiao ,&nbsp;Xinyu Wang ,&nbsp;Pengli Jin ,&nbsp;Cheng Cheng ,&nbsp;Xiubo Tian","doi":"10.1016/j.vacuum.2025.114472","DOIUrl":"10.1016/j.vacuum.2025.114472","url":null,"abstract":"<div><div>Pulsed vacuum discharge is widely used in the deposition of films on the inner walls of tubes for lubrication and corrosion prevention. However, the mechanisms by which plasma impacts this process keep ambiguous due to the limited knowledge about plasma characteristics such as spatial-temporal evolution and discharge in tubes of various diameter and length. In this study, high-voltage pulsed-DC driven hollow cathode discharge (HCD) is performed on a metal tube system for the deposition of anti-corrosive films on the inner surface. The current-voltage (CV) characteristics are analyzed in addition to Langmuir probe diagnostics and optical emission spectroscopy (OES). A brief voltage breakdown occurs at the beginning of the discharge, lasting approximately 3–4 μs, but the discharge quickly stabilizes, followed by a steady voltage state. The voltage cathode drop (Uc) is sufficiently high to sustain the discharge, thereby generating secondary electrons (γ-electrons) for excitation and ionization. And, a full HCD is established with a sufficient quantity of γ-electrons at higher discharge voltages (e.g., magnitude lager than 4000 V in our case), indicating that substantial voltage levels are necessary to develop adhesive, high-quality films. The discharge persists even after reaching the peak discharge current, as indicated by the temporal distribution of electron density and emission line ratios obtained from the Langmuir probe and OES measurements, respectively. In conjunction with the Langmuir probe measurements, the effective prediction of electron density and temperature using OES, based on the collision radiative (CR) model, reveals a more suitable method for evaluating plasma properties within tubes, enhancing the understanding of plasma-assisted film growth. Overall, the discharge characteristics, especially the pulse-driven evolution, can be better characterized by CV and Langmuir probe measurements. These reveal the evolution mechanisms of discharge voltage, density, and γ-electrons, which impact film properties such as brittleness induced by insufficient HCD. OES-CR provides a convenient, non-intrusive means to determine plasma radicals and densities, evaluating their effects on film formation, despite limitations in small-diameter tubes which are difficult for intrusive measurements. This comparative investigation thus elucidates the discharge characteristics and feasible methods for revealing the underlying mechanisms associated with pulse-driven discharges and film deposition in diverse tube configurations.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114472"},"PeriodicalIF":3.8,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"First-principles calculations and theoretical analysis of π plasmon in graphene and graphite: From 2D to 3D","authors":"Pengfei Li ,&nbsp;Ningju Hui","doi":"10.1016/j.vacuum.2025.114424","DOIUrl":"10.1016/j.vacuum.2025.114424","url":null,"abstract":"<div><div>Plasmon excitations in graphite, graphene, and their intermediate states have been investigated using first-principles linear response time-dependent density functional theory (LR-TDDFT) within the random phase approximation (RPA) framework, as well as through theoretical analysis based on the tight-binding model. Our findings reveal that in three-dimensional graphite, the dispersion relation of <span><math><mi>π</mi></math></span> plasmons follows the pattern <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>π</mi></mrow></msub><mrow><mo>(</mo><mi>q</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mi>ω</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>0</mn></mrow></msub><mo>+</mo><mi>α</mi><msup><mrow><mi>q</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> as q approaches zero, where <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>0</mn></mrow></msub></math></span> represents the exact excitation energy at q=0 and <span><math><mi>α</mi></math></span> is a fitting parameter. In contrast, in two-dimensional graphene, the dispersion relation exhibits a distinct characteristic given by <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>π</mi></mrow></msub><mrow><mo>(</mo><mi>q</mi><mo>)</mo></mrow><mo>=</mo><msqrt><mrow><msubsup><mrow><mi>E</mi></mrow><mrow><mi>g</mi><mo>,</mo><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>+</mo><mi>β</mi><mi>q</mi></mrow></msqrt></mrow></math></span>, where <span><math><msub><mrow><mi>E</mi></mrow><mrow><mi>g</mi><mo>,</mo><mi>M</mi></mrow></msub></math></span> is the band gap at the M point in the Brillouin zone and <span><math><mi>β</mi></math></span> is another fitting parameter. This significant difference can be attributed to the presence or absence of interlayer Coulomb interactions. Furthermore, we conducted an in-depth analysis of how the excitation energies of <span><math><mi>π</mi></math></span> plasmons vary with interlayer spacing. The results indicate that the excitation energy follows the form <span><math><mrow><msub><mrow><mi>ω</mi></mrow><mrow><mi>p</mi><mo>,</mo><mn>0</mn></mrow></msub><mo>=</mo><msqrt><mrow><msubsup><mrow><mi>E</mi></mrow><mrow><mi>g</mi><mo>,</mo><mi>M</mi></mrow><mrow><mn>2</mn></mrow></msubsup><mo>+</mo><mi>γ</mi><mo>/</mo><mi>d</mi></mrow></msqrt></mrow></math></span>, where d is the distance between two layers and <span><math><mi>γ</mi></math></span> is a fitting constant. Specifically, as the interlayer spacing in graphite gradually increases, the excitation energy of plasmons progressively decreases, eventually converging towards the value observed in graphene.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114424"},"PeriodicalIF":3.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144196227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of heat load on tungsten material by hydrogen plasma stream of PPA","authors":"A. Ahmed,&nbsp;S. Singha,&nbsp;P. Baruah,&nbsp;P.P. Kalita,&nbsp;N.K. Neog,&nbsp;T.K. Borthakur","doi":"10.1016/j.vacuum.2025.114473","DOIUrl":"10.1016/j.vacuum.2025.114473","url":null,"abstract":"<div><div>Interaction of pulsed hydrogen plasma, with an energy density ∼ 0.22 MJ/m², that is below the melting threshold of tungsten, on fusion-relevant tungsten material has a significant importance. This plasma is produced in a pulsed plasma accelerator, developed at CPP-IPR as a test-bed facility for fusion-relevant material interaction study. The impact of this relatively low energy density plasma on W material shows different surface modifications depending on the number of shots. The influence of an external longitudinal magnetic field on these surface modifications has been observed. Appearance of blisters, formation and propagation of cracks ∼ μm size are studied under different number of shots as they contribute to W dust generation. Re-deposition of impurity is observed along with W dust forming W₂C layer on plasma irradiated W surface. The plasma impact causes strain in the material and the lattice strain penetrates deeper into the material with increase in number of plasma shots. Accumulation of tensile residual stress after plasma impact makes the W material prone to crack formation. This residual stress is estimated using d-sin²ѱ method and has a value ∼ (23.51 ± 2.22) GPa in absence of magnetic field and the stress is relieved with the crack formation on material surface.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114473"},"PeriodicalIF":3.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144231438","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial Board and Vacuum units","authors":"","doi":"10.1016/S0042-207X(25)00451-8","DOIUrl":"10.1016/S0042-207X(25)00451-8","url":null,"abstract":"","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"238 ","pages":"Article 114461"},"PeriodicalIF":3.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144189938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Operational features of a wide-aperture forevacuum-pressure plasma-cathode pulsed electron beam source based on a planar magnetron (sputtering) discharge","authors":"Andrey V. Kazakov,&nbsp;Valery E. Arkatov,&nbsp;Yuriy A. Burachevsky,&nbsp;Efim M. Oks,&nbsp;Nikolay A. Panchenko","doi":"10.1016/j.vacuum.2025.114470","DOIUrl":"10.1016/j.vacuum.2025.114470","url":null,"abstract":"<div><div>We describe our investigations of the operational features of a wide-aperture forevacuum-pressure plasma-cathode pulsed (0.5–1.5 ms) electron beam source utilizing a planar magnetron plasma discharge system. The accelerating voltage (up to 10 kV), which is used to extract, form, and accelerate the electron beam, influences the magnetron discharge initiation; increased acceleration voltage leads to a decrease in the initiation voltage and delay time of the magnetron discharge. This is due to a “parasitic” high-voltage glow discharge that occurs when high voltage is applied to the accelerating gap of the source. For gas pressure greater than 4 Pa, the magnetron discharge voltage is lower with electron beam generation. The magnetron discharge voltage decreases with increasing gas pressure (4–16 Pa) and accelerating voltage, and when argon is used rather than nitrogen. The electron emission current and hence e-beam current increases with increasing gas pressure. The observed decrease in magnetron discharge voltage and the change in emission properties of the magnetron discharge plasma are due to the “back-streaming” ion flux from the beam-produced plasma. The use of a planar magnetron discharge in the source ensures the formation of a wide-aperture (radius of up to 40 mm) electron beam with good homogeneity.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114470"},"PeriodicalIF":3.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on antibacterial efficiency of ZnO functionalized plasma-treated PMMA and PS polymer films for Bio-medical applications","authors":"Nandhu Varshini Gnanasekar,&nbsp;Shanmugavelayutham Gurusamy","doi":"10.1016/j.vacuum.2025.114469","DOIUrl":"10.1016/j.vacuum.2025.114469","url":null,"abstract":"<div><div>The utilization of polymer films in medical and food applications is often hindered by issues such as poor adhesion, inadequate antibacterial properties, and hydrophobic surfaces. Non-thermal plasma treatment has emerged as an effective technique to address these limitations and enhance film performance. This study investigates the effects of Zinc oxide(ZnO) functionalization on plasma-treated Polymethyl methacrylate(PMMA) and Polystyrene(PS) films. ZnO nanoparticles, synthesized through transferred arc plasma system, are characterized by UV–visible spectroscopy and X-ray diffraction analysis(XRD), revealing band gap energy of 3.29eV and crystalline size of 44.73 nm. Surface modifications of polymer films are achieved using Dielectric Barrier Discharge (DBD) plasma at 30 kV with argon gas for various exposure durations, followed by dip-coating in ZnO solution. Characterization results shows substantial improvements in hydrophilicity, chemical structure and surface roughness. Optical Emission Spectroscopy(OES) analysis reveals that argon plasma exhibits an electron temperature of 0.8 eV and electron density of 1.6 × 10¹⁶ cm⁻³. Antibacterial studies reveal that ZnO-functionalized plasma-treated PMMA films for 15 min exhibit superior antibacterial performance, showing a 12.5 ± 0.3 mm inhibition zone, while ZnO-functionalized plasma-treated PS films display a 9.3 ± 0.3 mm inhibition zone. This study highlights the potential of DBD plasma and ZnO coating to address existing challenges, enhancing polymer films for its use in bio-medical applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"240 ","pages":"Article 114469"},"PeriodicalIF":3.8,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144204508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}