The dissimilar titanium alloys Ti150 and Ti180 were brazed using TiZrCuNi filler metal within 890-940 °C for 10 min. Effective joining has been achieved through systematic parameter optimization. Through systematic optimization of the processing parameters, effective bonding was successfully achieved. At relatively low temperatures, excessive formation of brittle intermetallic compounds, namely (Ti,Zr)2(Cu,Ni), was observed, leading to pronounced hardness mismatch and preferential crack initiation. The diffusion-affected zone was mainly composed of acicular and blocky α/β-Ti phases. Increasing the brazing temperature promotes the fragmentation of coarse intermetallic compounds into finer precipitates, thereby enabling effective regulation of the interfacial microstructure.The maximum shear strength of 432 MPa was achieved at 930 °C, corresponding well with the optimal homogenization of the microstructure. However, when the temperature was further increased to 940 °C, significant grain coarsening occurred in the base material, resulting in a gradual deterioration of the mechanical properties.
{"title":"Microstructure and mechanical properties of Ti150/Ti180 dissimilar brazed joints with titanium-based filler metal","authors":"Xinlei Ding , Yunjia Huang , Wei Guo , Jiapeng Dong , Da Zhang , Yeming Guo","doi":"10.1016/j.vacuum.2026.115164","DOIUrl":"10.1016/j.vacuum.2026.115164","url":null,"abstract":"<div><div>The dissimilar titanium alloys Ti150 and Ti180 were brazed using TiZrCuNi filler metal within 890-940 °C for 10 min. Effective joining has been achieved through systematic parameter optimization. Through systematic optimization of the processing parameters, effective bonding was successfully achieved. At relatively low temperatures, excessive formation of brittle intermetallic compounds, namely (Ti,Zr)<sub>2</sub>(Cu,Ni), was observed, leading to pronounced hardness mismatch and preferential crack initiation. The diffusion-affected zone was mainly composed of acicular and blocky α/β-Ti phases. Increasing the brazing temperature promotes the fragmentation of coarse intermetallic compounds into finer precipitates, thereby enabling effective regulation of the interfacial microstructure.The maximum shear strength of 432 MPa was achieved at 930 °C, corresponding well with the optimal homogenization of the microstructure. However, when the temperature was further increased to 940 °C, significant grain coarsening occurred in the base material, resulting in a gradual deterioration of the mechanical properties.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115164"},"PeriodicalIF":3.9,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174095","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}
Pub Date : 2026-02-07DOI: 10.1016/j.vacuum.2026.115166
Piotr Kałuziak, Jan Raczyński, Semir El-Ahmar, Marta Przychodnia, Marek Nowicki, Ryszard Czajka, Wojciech Koczorowski
In this work, we investigate Flash Evaporation Epitaxy (FEE) as a method for fabricating InSb/GaAs heterostructures exhibiting intrinsic electrical variability while preserving structural and chemical homogeneity. n-InSb/i-GaAs systems were grown using a modified FEE-based high-vacuum setup. The elemental mapping in both the plan view and the cross-section shows a close stoichiometric distribution of the antimony and indium atoms, and a homogeneous incorporation of oxygen with a low content at a level of 1 at.%. SEM and AFM analyses confirm a uniform surface morphology. Electrical characterization of full wafers and progressively structured areas reveals variations in sheet resistance with the range of X-Y exceeding experimental uncertainty. These variations form a statistical distribution of electrical parameters resulting from the properties of the FEE method rather than from significant structural or stoichiometry non-uniformity. This distribution defines the material-based uniqueness of the films. While usually considered a limitation, it is demonstrated here as a functional advantage for generating unique physical signatures applicable to hardware-level authenticity-verification systems.
{"title":"Material-based uniqueness in InSb thin films: Flash Evaporation Epitaxy as a tool for secure device engineering","authors":"Piotr Kałuziak, Jan Raczyński, Semir El-Ahmar, Marta Przychodnia, Marek Nowicki, Ryszard Czajka, Wojciech Koczorowski","doi":"10.1016/j.vacuum.2026.115166","DOIUrl":"10.1016/j.vacuum.2026.115166","url":null,"abstract":"<div><div>In this work, we investigate Flash Evaporation Epitaxy (FEE) as a method for fabricating InSb/GaAs heterostructures exhibiting intrinsic electrical variability while preserving structural and chemical homogeneity. n-InSb/i-GaAs systems were grown using a modified FEE-based high-vacuum setup. The elemental mapping in both the plan view and the cross-section shows a close stoichiometric distribution of the antimony and indium atoms, and a homogeneous incorporation of oxygen with a low content at a level of 1 at.%. SEM and AFM analyses confirm a uniform surface morphology. Electrical characterization of full wafers and progressively structured areas reveals variations in sheet resistance with the range of X-Y exceeding experimental uncertainty. These variations form a statistical distribution of electrical parameters resulting from the properties of the FEE method rather than from significant structural or stoichiometry non-uniformity. This distribution defines the material-based uniqueness of the films. While usually considered a limitation, it is demonstrated here as a functional advantage for generating unique physical signatures applicable to hardware-level authenticity-verification systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115166"},"PeriodicalIF":3.9,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174105","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}
Pub Date : 2026-02-06DOI: 10.1016/j.vacuum.2026.115165
Qiaoling Wang , Menghao Jiang , Zhikang Yang , Zhipeng Yuan , Yilu Zhang , Datian Cui , Yiyou Tu , Ting Yuan , Fang Liu , Liang Huang , Jin Peng , Zenglei Ni , Wenyi Huo
Galvanic corrosion limits the durability of multi-layered aluminum alloys in automotive heat exchangers, particularly in chloride-containing environments. This study investigated brazing-induced microstructural effects on the corrosion behavior of AA4343/AA3xxx/AA4343 multi-layered aluminum sheets, addressing interlayer and particle/matrix galvanic interactions. Using immersion tests in 3.5 wt% NaCl, electrochemical measurements, and thorough microstructural characterization, the results show that α-Al(Fe,Mn)Si particles act as cathodic sites, initiating pitting at particle/matrix interfaces, while grain boundary Al4Cu2Mg8Si7 (Q phase) precipitates undergo Mg dissolution and Cu enrichment, forming cathodic paths that promote intergranular corrosion. Brazing exacerbates corrosion by enhancing Si diffusion and Cu segregation at the clad/core interface, increasing galvanic coupling and intensifying both pitting and intergranular attack. These findings elucidate the synergistic roles of intermetallic particles, grain boundary phases, and brazing-induced microstructures in localized corrosion. This work provides critical insights for optimizing alloy composition, brazing processes, and service life prediction and advances the design of corrosion-resistant aluminum heat exchangers for new energy vehicles.
{"title":"Brazing-induced microstructural effects on galvanic corrosion of AA4343/AA3xxx multi-layered alloys","authors":"Qiaoling Wang , Menghao Jiang , Zhikang Yang , Zhipeng Yuan , Yilu Zhang , Datian Cui , Yiyou Tu , Ting Yuan , Fang Liu , Liang Huang , Jin Peng , Zenglei Ni , Wenyi Huo","doi":"10.1016/j.vacuum.2026.115165","DOIUrl":"10.1016/j.vacuum.2026.115165","url":null,"abstract":"<div><div>Galvanic corrosion limits the durability of multi-layered aluminum alloys in automotive heat exchangers, particularly in chloride-containing environments. This study investigated brazing-induced microstructural effects on the corrosion behavior of AA4343/AA3xxx/AA4343 multi-layered aluminum sheets, addressing interlayer and particle/matrix galvanic interactions. Using immersion tests in 3.5 wt% NaCl, electrochemical measurements, and thorough microstructural characterization, the results show that α-Al(Fe,Mn)Si particles act as cathodic sites, initiating pitting at particle/matrix interfaces, while grain boundary Al<sub>4</sub>Cu<sub>2</sub>Mg<sub>8</sub>Si<sub>7</sub> (Q phase) precipitates undergo Mg dissolution and Cu enrichment, forming cathodic paths that promote intergranular corrosion. Brazing exacerbates corrosion by enhancing Si diffusion and Cu segregation at the clad/core interface, increasing galvanic coupling and intensifying both pitting and intergranular attack. These findings elucidate the synergistic roles of intermetallic particles, grain boundary phases, and brazing-induced microstructures in localized corrosion. This work provides critical insights for optimizing alloy composition, brazing processes, and service life prediction and advances the design of corrosion-resistant aluminum heat exchangers for new energy vehicles.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"248 ","pages":"Article 115165"},"PeriodicalIF":3.9,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146193213","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}
This study numerically investigates a 915 MHz iplas-type MPCVD reactor. Electromagnetic analysis identified the TE10 mode in the annular waveguide and the TM012 mode in the resonant cavity, clarifying the slot antenna's magnetic coupling mechanism. Subsequently, multi-dimensional simulations were conducted on the iplas cavity. Firstly, a plasma simulation was carried out based on the phenomenological method, and it was found that there were limitations in characterizing the spatial variations. To more accurately simulate plasma spatial distribution, an innovative approach was adopted, which reasonably simplified the non-axisymmetric three-dimensional (3D) cavity into a two-dimensional (2D) axisymmetric structure, and a self-consistent pure hydrogen plasma simulation was then carried out. The results showed that, at a fixed power, an increase in pressure led to plasma contraction and an increase in electron number density; at a fixed pressure, an increase in power caused plasma expansion, and when exceeding the critical value, the central electron number density decreased. Three sets of process parameters were selected for simulation and experiment validation, verifying the accuracy of the simulation prediction results using this simplified structure. Under the simulated process conditions (30 kW-10.5 kPa), high-quality 6-inch polycrystalline diamond films were successfully deposited.
{"title":"Numerical simulation of plasma in a 915 MHz MPCVD reactor using a simplified 2D structure","authors":"Xue Liu, Cuiting Zhang, Xianyi Lv, Qiliang Wang, Liuan Li, Guangtian Zou","doi":"10.1016/j.vacuum.2026.115159","DOIUrl":"10.1016/j.vacuum.2026.115159","url":null,"abstract":"<div><div>This study numerically investigates a 915 MHz iplas-type MPCVD reactor. Electromagnetic analysis identified the TE<sub>10</sub> mode in the annular waveguide and the TM<sub>012</sub> mode in the resonant cavity, clarifying the slot antenna's magnetic coupling mechanism. Subsequently, multi-dimensional simulations were conducted on the iplas cavity. Firstly, a plasma simulation was carried out based on the phenomenological method, and it was found that there were limitations in characterizing the spatial variations. To more accurately simulate plasma spatial distribution, an innovative approach was adopted, which reasonably simplified the non-axisymmetric three-dimensional (3D) cavity into a two-dimensional (2D) axisymmetric structure, and a self-consistent pure hydrogen plasma simulation was then carried out. The results showed that, at a fixed power, an increase in pressure led to plasma contraction and an increase in electron number density; at a fixed pressure, an increase in power caused plasma expansion, and when exceeding the critical value, the central electron number density decreased. Three sets of process parameters were selected for simulation and experiment validation, verifying the accuracy of the simulation prediction results using this simplified structure. Under the simulated process conditions (30 kW-10.5 kPa), high-quality 6-inch polycrystalline diamond films were successfully deposited.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115159"},"PeriodicalIF":3.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174108","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}
Herein, an interface-engineered strategy was developed to enhance the structural and electrical properties of tin monoxide (SnO) thin films by using tellurium (Te) as a surface capping layer and controlling the annealing atmosphere via rapid thermal annealing (RTA). The Te layer effectively stabilized the SnO surface and suppressed Sn valence drift. X-ray photoelectron spectroscopy depth profiling revealed that RTA under the N2 atmosphere significantly promoted Te0 diffusion into SnO. X-ray diffraction confirmed improved crystallinity and grain coarsening in the N2-annealed sample, attributed to interfacial atomic rearrangement. These findings highlight the synergistic role of Te coating and inert-atmosphere annealing in tuning interfacial defect chemistry and enhancing the physical properties of p-type oxide semiconductors.
{"title":"Investigating the impact of rapid thermal annealing atmosphere on the properties of sputtered SnO thin films with a tellurium capping layer","authors":"Bojun Zhang , Kai-Jhih Gan , Zefu Zhao , Jialong Xiang , Zhibo Zeng , Kuei-Shu Chang-Liao , Chao-Yi Fang , Dun-Bao Ruan","doi":"10.1016/j.vacuum.2026.115148","DOIUrl":"10.1016/j.vacuum.2026.115148","url":null,"abstract":"<div><div>Herein, an interface-engineered strategy was developed to enhance the structural and electrical properties of tin monoxide (SnO) thin films by using tellurium (Te) as a surface capping layer and controlling the annealing atmosphere via rapid thermal annealing (RTA). The Te layer effectively stabilized the SnO surface and suppressed Sn valence drift. X-ray photoelectron spectroscopy depth profiling revealed that RTA under the N<sub>2</sub> atmosphere significantly promoted Te<sup>0</sup> diffusion into SnO. X-ray diffraction confirmed improved crystallinity and grain coarsening in the N<sub>2</sub>-annealed sample, attributed to interfacial atomic rearrangement. These findings highlight the synergistic role of Te coating and inert-atmosphere annealing in tuning interfacial defect chemistry and enhancing the physical properties of p-type oxide semiconductors.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115148"},"PeriodicalIF":3.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174096","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}
Pub Date : 2026-02-05DOI: 10.1016/j.vacuum.2026.115163
Bin Li , Qianxu Wang , Jianglong Wei , Fang Wang , Lunhuan Xia , Yue Yun , Wei Yi , Yuanlai Xie
Neutral beam injectors (NBIs) are widely employed in fusion devices, where the background gas distribution inside the beamline vessel strongly influences both neutralization efficiency and reionization loss. The mainstream calculation methods are Monte Carlo or angular coefficient methods. However, the large size and intricate internal structure of cryopumps make whole-vessel computations difficult. This paper presents a two-step approach. First, the effective capture coefficient of each cryopump unit is obtained with a detailed Test Particle Monte Carlo (TPMC) model. Second, a reduced geometry of the beamline vessel and components-especially the cryopumps-is used to build the background gas distribution. Line integrals of this distribution evaluate neutralization efficiency and reionization loss. Comparisons between measured and computed pressures in the operational EAST (Experimental Advanced Superconducting Tokamak) NBI and the CRAFT (Comprehensive Research Facility for Fusion Technology) NBI testbed verify the method's generality, and the same procedure is applied to upgrade EAST NBI and BEST (Burning plasma Experimental Superconducting Tokamak) NBI to predict its gas profile and the beam performance.
中性束注入器广泛应用于核聚变装置中，其中束线容器内的背景气体分布对中和效率和再电离损失有很大影响。主流的计算方法是蒙特卡罗法或角系数法。然而，低温泵体积大，内部结构复杂，给整个容器的计算带来了困难。本文提出了一种两步法。首先，利用详细的测试粒子蒙特卡罗（TPMC）模型获得了各低温泵单元的有效捕获系数。其次，利用简化的光束线容器和组件（尤其是低温泵）的几何形状来构建背景气体分布。这种分布的线积分评价中和效率和再电离损失。在EAST (Experimental Advanced Superconducting Tokamak) NBI和CRAFT (Comprehensive Research Facility for Fusion Technology) NBI试验台运行的实测压力和计算压力的比较验证了该方法的通用性，并将同样的方法应用于EAST NBI和BEST (Burning plasma Experimental Superconducting Tokamak) NBI的升级，以预测其气体分布和光束性能。
{"title":"A simplified method for calculating background gas distribution of large-scale neutral beam injector","authors":"Bin Li , Qianxu Wang , Jianglong Wei , Fang Wang , Lunhuan Xia , Yue Yun , Wei Yi , Yuanlai Xie","doi":"10.1016/j.vacuum.2026.115163","DOIUrl":"10.1016/j.vacuum.2026.115163","url":null,"abstract":"<div><div>Neutral beam injectors (NBIs) are widely employed in fusion devices, where the background gas distribution inside the beamline vessel strongly influences both neutralization efficiency and reionization loss. The mainstream calculation methods are Monte Carlo or angular coefficient methods. However, the large size and intricate internal structure of cryopumps make whole-vessel computations difficult. This paper presents a two-step approach. First, the effective capture coefficient of each cryopump unit is obtained with a detailed Test Particle Monte Carlo (TPMC) model. Second, a reduced geometry of the beamline vessel and components-especially the cryopumps-is used to build the background gas distribution. Line integrals of this distribution evaluate neutralization efficiency and reionization loss. Comparisons between measured and computed pressures in the operational EAST (Experimental Advanced Superconducting Tokamak) NBI and the CRAFT (Comprehensive Research Facility for Fusion Technology) NBI testbed verify the method's generality, and the same procedure is applied to upgrade EAST NBI and BEST (Burning plasma Experimental Superconducting Tokamak) NBI to predict its gas profile and the beam performance.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115163"},"PeriodicalIF":3.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174107","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}
Pub Date : 2026-02-05DOI: 10.1016/j.vacuum.2026.115162
J. Meng , J.C. Yang , C. Luo , W.S. Yang , W.J. Xie , Z. Chai , G.D. Shen , J.X. Wu , C.C. Li , J.L. Liu , J.Q. Jiao , X.J. Lin , N.F. Wei , Y.P. Wan , Y.M. Gao , X.R. Zhu , X.L. Ma , K.X. Zhong , R.P. Zhang , X.P. Zhang
The High Intensity heavy ion Accelerator Facility (HIAF) is the world's first heavy ion research device that integrates superconducting linear, synchronous acceleration, and storage rings. Its vacuum system is critical for the stable transport of high intensity beams and long-term reliable operation. This paper systematically presents the technical challenges, key innovations, and engineering achievements of the nearly 2-km-long HIAF vacuum system. To reduce the eddy current effect caused by rapidly changing magnetic fields, the Booster Ring (BRing) magnetic vacuum chamber innovatively adopts a titanium alloy-lined ultra-thin-walled (wall thickness 0.3 mm) structure based on the combination of 3D printing and Non-Evaporable Getter (NEG) coating technology. This type of vacuum chamber accounts for 60% of the BRing. In addition, by optimizing the outgassing process and chamber structure of the built-in components, an average pressure of 4.7 × 10−10 Pa was achieved, representing the world's largest room temperature ultra-thin-walled vacuum system; Faced with the challenge of limited installation space for the Spectrometer Ring (SRing) electronic-cooling system, an integrated solution combining sputter ion pumps, built-in titanium wire evaporation, and NEG coating was implemented. The system ultimately achieved an average pressure of 1.0 × 10−9 Pa; For the high radiation area of the High energy Fragment Separator (HFRS), a self-developed split type sealing flange is used to achieve remote disassembly and reliable sealing of pipelines, maintaining a pressure of 2.5 × 10−6 Pa; In addition, a 3 mm ultra-thin integrated baking jacket has been developed, achieving precise high-temperature baking of complex vacuum systems. The design of the HIAF vacuum system was initiated in 2018, following multiple iterations and process validations, its large-scale installation was launched in March 2024. Full integration of the system was achieved by September of the same year, completed the entire installation and commissioning process within a six-month period. The vacuum performance of each subsystem ultimately exceeded the design specifications, providing a new technological path and engineering paradigm for the design and construction of future large-scale accelerator vacuum systems.
高强度重离子加速器设施（HIAF）是世界上第一个重离子研究设备，集成了超导线性、同步加速和存储环。它的真空系统对高强度光束的稳定传输和长期可靠运行至关重要。本文系统地介绍了近2公里长的HIAF真空系统的技术挑战、关键创新和工程成果。为了减少磁场快速变化带来的涡流效应，助推环（BRing）磁真空室创新性地采用了基于3D打印和非蒸发吸气剂（NEG）涂层技术相结合的钛合金衬里超薄壁（壁厚0.3 mm）结构。这种类型的真空室占整个真空室的60%。此外，通过优化出气工艺和内置组件的腔室结构，实现了4.7 × 10−10 Pa的平均压力，代表了世界上最大的室温超薄壁真空系统；针对spectrum Ring （string）电子冷却系统安装空间有限的问题，采用了溅射离子泵、内置钛丝蒸发和NEG涂层相结合的集成解决方案。该系统最终实现了平均压力为1.0 × 10−9 Pa；高能碎片分离器（high energy Fragment Separator， HFRS）的高辐射区采用自主研发的分体式密封法兰，实现管道的远程拆卸和可靠密封，压力保持在2.5 × 10−6 Pa；此外，还开发了3mm超薄集成烘烤套，实现了复杂真空系统的精确高温烘烤。HIAF真空系统的设计始于2018年，经过多次迭代和工艺验证，其大规模安装于2024年3月启动。同年9月实现了系统的全面集成，在6个月内完成了整个安装和调试过程。各分系统的真空性能最终都超过了设计指标，为未来大型加速器真空系统的设计和建造提供了新的技术路径和工程范式。
{"title":"Requirements, design, and challenges of the HIAF vacuum system","authors":"J. Meng , J.C. Yang , C. Luo , W.S. Yang , W.J. Xie , Z. Chai , G.D. Shen , J.X. Wu , C.C. Li , J.L. Liu , J.Q. Jiao , X.J. Lin , N.F. Wei , Y.P. Wan , Y.M. Gao , X.R. Zhu , X.L. Ma , K.X. Zhong , R.P. Zhang , X.P. Zhang","doi":"10.1016/j.vacuum.2026.115162","DOIUrl":"10.1016/j.vacuum.2026.115162","url":null,"abstract":"<div><div>The High Intensity heavy ion Accelerator Facility (HIAF) is the world's first heavy ion research device that integrates superconducting linear, synchronous acceleration, and storage rings. Its vacuum system is critical for the stable transport of high intensity beams and long-term reliable operation. This paper systematically presents the technical challenges, key innovations, and engineering achievements of the nearly 2-km-long HIAF vacuum system. To reduce the eddy current effect caused by rapidly changing magnetic fields, the Booster Ring (BRing) magnetic vacuum chamber innovatively adopts a titanium alloy-lined ultra-thin-walled (wall thickness 0.3 mm) structure based on the combination of 3D printing and Non-Evaporable Getter (NEG) coating technology. This type of vacuum chamber accounts for 60% of the BRing. In addition, by optimizing the outgassing process and chamber structure of the built-in components, an average pressure of 4.7 × 10<sup>−10</sup> Pa was achieved, representing the world's largest room temperature ultra-thin-walled vacuum system; Faced with the challenge of limited installation space for the Spectrometer Ring (SRing) electronic-cooling system, an integrated solution combining sputter ion pumps, built-in titanium wire evaporation, and NEG coating was implemented. The system ultimately achieved an average pressure of 1.0 × 10<sup>−9</sup> Pa; For the high radiation area of the High energy Fragment Separator (HFRS), a self-developed split type sealing flange is used to achieve remote disassembly and reliable sealing of pipelines, maintaining a pressure of 2.5 × 10<sup>−6</sup> Pa; In addition, a 3 mm ultra-thin integrated baking jacket has been developed, achieving precise high-temperature baking of complex vacuum systems. The design of the HIAF vacuum system was initiated in 2018, following multiple iterations and process validations, its large-scale installation was launched in March 2024. Full integration of the system was achieved by September of the same year, completed the entire installation and commissioning process within a six-month period. The vacuum performance of each subsystem ultimately exceeded the design specifications, providing a new technological path and engineering paradigm for the design and construction of future large-scale accelerator vacuum systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"248 ","pages":"Article 115162"},"PeriodicalIF":3.9,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146161661","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}
Pub Date : 2026-02-04DOI: 10.1016/j.vacuum.2026.115161
Bilal Ahmed , Muhammad Bilal Tahir , Arafa A. Yagob , Mohja Jaouadi , Solima I. Yagoob
Acquiring hydride materials that are structurally stable, have good hydrogen absorption thermodynamics, and have several useful physical properties is still a major challenge for next-generation hydrogen storage methods. This study presents the inaugural full first-principles analysis of hitherto unexamined cubic CaX3H9 (X = Cr, Mn, Fe) hydrides, employing density functional theory inside the CASTEP framework. Structural optimization, negative formation enthalpies (−0.081 to −0.078 eV/atom), phonon dispersion without imaginary modes, and ab initio molecular dynamics simulations up to 800 K all show that they are thermodynamically, dynamically, and thermally stable. Calculations of the electronic structure show that substantial transition-metal 3d–H-1s hybridization causes inherent metallic behavior. This is also related to how hydrogen moves and how it can be reversed. Spin-polarized computations reveal unique magnetic ground states: CaCr3H9 and CaFe3H9 display ferromagnetism, but CaMn3H9 stabilizes in an antiferromagnetic arrangement. The elastic constant analysis shows that all of the compounds are mechanically stable. However, CaMn3H9 and CaFe3H9 are ductile (B/G > 2.2), whereas CaCr3H9 is brittle. Optical spectra show that the material absorbs a lot of light in the visible to UV range, mostly because of interband transitions between transition-metal d-states. This shows that the material has more optoelectronic functions. Most crucially, CaX3H9 hydrides store hydrogen well, with gravimetric capacities of 4.35, 4.24, and 4.19 wt% and volumetric capacities of 176.8–183.0 gH2 L−1 for CaX3H9 (X = Cr, Mn, Fe), respectively. They also have moderate desorption temperatures (521–538 K). These findings identify CaX3H9 as an innovative and adjustable category of perovskite-like hydrides that integrate structural stability, metallic conductivity, magnetic ordering, and effective hydrogen storage capabilities, presenting a viable foundation for enhanced solid-state hydrogen energy systems.
{"title":"Probing the structural, electronic, optical, magnetic and mechanical properties of CaX3H9 (X = Cr, Mn, Fe) hydrides towards next-generation hydrogen storage applications","authors":"Bilal Ahmed , Muhammad Bilal Tahir , Arafa A. Yagob , Mohja Jaouadi , Solima I. Yagoob","doi":"10.1016/j.vacuum.2026.115161","DOIUrl":"10.1016/j.vacuum.2026.115161","url":null,"abstract":"<div><div>Acquiring hydride materials that are structurally stable, have good hydrogen absorption thermodynamics, and have several useful physical properties is still a major challenge for next-generation hydrogen storage methods. This study presents the inaugural full first-principles analysis of hitherto unexamined cubic CaX<sub>3</sub>H<sub>9</sub> (X = Cr, Mn, Fe) hydrides, employing density functional theory inside the CASTEP framework. Structural optimization, negative formation enthalpies (−0.081 to −0.078 eV/atom), phonon dispersion without imaginary modes, and ab initio molecular dynamics simulations up to 800 K all show that they are thermodynamically, dynamically, and thermally stable. Calculations of the electronic structure show that substantial transition-metal 3d–H-1s hybridization causes inherent metallic behavior. This is also related to how hydrogen moves and how it can be reversed. Spin-polarized computations reveal unique magnetic ground states: CaCr<sub>3</sub>H<sub>9</sub> and CaFe<sub>3</sub>H<sub>9</sub> display ferromagnetism, but CaMn<sub>3</sub>H<sub>9</sub> stabilizes in an antiferromagnetic arrangement. The elastic constant analysis shows that all of the compounds are mechanically stable. However, CaMn<sub>3</sub>H<sub>9</sub> and CaFe<sub>3</sub>H<sub>9</sub> are ductile (B/G > 2.2), whereas CaCr<sub>3</sub>H<sub>9</sub> is brittle. Optical spectra show that the material absorbs a lot of light in the visible to UV range, mostly because of interband transitions between transition-metal d-states. This shows that the material has more optoelectronic functions. Most crucially, CaX<sub>3</sub>H<sub>9</sub> hydrides store hydrogen well, with gravimetric capacities of 4.35, 4.24, and 4.19 wt% and volumetric capacities of 176.8–183.0 gH<sub>2</sub> L<sup>−1</sup> for CaX<sub>3</sub>H<sub>9</sub> (X = Cr, Mn, Fe), respectively. They also have moderate desorption temperatures (521–538 K). These findings identify CaX<sub>3</sub>H<sub>9</sub> as an innovative and adjustable category of perovskite-like hydrides that integrate structural stability, metallic conductivity, magnetic ordering, and effective hydrogen storage capabilities, presenting a viable foundation for enhanced solid-state hydrogen energy systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115161"},"PeriodicalIF":3.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174097","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}
Pub Date : 2026-02-04DOI: 10.1016/j.vacuum.2026.115158
Dezhi Xiao , Chuyang Lin , Xinyu Wang , Xiubo Tian
Silicon-based anodes are promising for high-energy-density lithium-ion batteries (LIB) but suffer from severe volume changes. Silicon-carbon (Si-C) composites mitigate these issues and chemical vapor deposition (CVD) enhances carbon adhesion though conventional CVD has low efficiency. Plasma-enhanced CVD (PECVD) improves this yet fundamental plasma-silicon interactions remain underexplored. To address this, a high-voltage pulse-DC plasma CVD system integrated with ultrasonic dispersion is developed, enabling Si powder transport into the plasma zone. Plasma simulations uncover temporal-spatial discharge evolution and cathode sheath electron heating while optical emission spectroscopy (OES) validates Ar-facilitated C2H2 dissociation. These findings reveal regulated energy transfer to Si surfaces and clarify interactions between plasma and silicon powders during carbon film formation. Material characterizations confirm amorphous carbon coverage, robust Si-C bonding, silicon-carbon crystallization and a promoted graphite phase with reduced disorders. According to the plasma properties, the characterization results are reasonably interpreted such as sputtering-induced crystallization and energy transfer/heating-driven graphite promotion. Electrochemical measurements show the carbon film initially fail to form a stable solid electrolyte interphase (SEI) layer due to silicon expansion and internal voids generated by plasma effects, however, the SEI layer stabilizes with lithiation/delithiation cycling and acceptable performance is achieved. This work fills the knowledge gap in plasma-silicon interactions, providing a low-temperature viable route for fabricating Si-C LIB anodes.
{"title":"High-voltage pulsed-DC driven low-pressure hollow-cathode plasma CVD synthesis of carbon-coated silicon for lithium-ion batteries","authors":"Dezhi Xiao , Chuyang Lin , Xinyu Wang , Xiubo Tian","doi":"10.1016/j.vacuum.2026.115158","DOIUrl":"10.1016/j.vacuum.2026.115158","url":null,"abstract":"<div><div>Silicon-based anodes are promising for high-energy-density lithium-ion batteries (LIB) but suffer from severe volume changes. Silicon-carbon (Si-C) composites mitigate these issues and chemical vapor deposition (CVD) enhances carbon adhesion though conventional CVD has low efficiency. Plasma-enhanced CVD (PECVD) improves this yet fundamental plasma-silicon interactions remain underexplored. To address this, a high-voltage pulse-DC plasma CVD system integrated with ultrasonic dispersion is developed, enabling Si powder transport into the plasma zone. Plasma simulations uncover temporal-spatial discharge evolution and cathode sheath electron heating while optical emission spectroscopy (OES) validates Ar-facilitated C<sub>2</sub>H<sub>2</sub> dissociation. These findings reveal regulated energy transfer to Si surfaces and clarify interactions between plasma and silicon powders during carbon film formation. Material characterizations confirm amorphous carbon coverage, robust Si-C bonding, silicon-carbon crystallization and a promoted graphite phase with reduced disorders. According to the plasma properties, the characterization results are reasonably interpreted such as sputtering-induced crystallization and energy transfer/heating-driven graphite promotion. Electrochemical measurements show the carbon film initially fail to form a stable solid electrolyte interphase (SEI) layer due to silicon expansion and internal voids generated by plasma effects, however, the SEI layer stabilizes with lithiation/delithiation cycling and acceptable performance is achieved. This work fills the knowledge gap in plasma-silicon interactions, providing a low-temperature viable route for fabricating Si-C LIB anodes.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115158"},"PeriodicalIF":3.9,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174100","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}
In this study, the tensile properties of SiCf/Ti60 composites under hot isostatic pressing (HIP) and 600 °C/100h states were investigated. The properties of thermal exposure SiCf/Ti60 composites were reduced by about 34 MPa compared to the properties of HIP composites with good thermal stability. The results show that SiCf/Ti60 composites have good matrix and interfacial thermal stability. The average grain size of matrix α-Ti in both states was 3.4-3.6 μm, the texture of α-Ti was <0001>//AD and <10-10>//AD, and the polar densities ranged from 6.9 to 7.4 to 2.7-3.1, respectively. The thickness of the interfacial reaction layer in both states was about 0.38-0.43 μm, the interfacial thickness increased slowly, and the silicon content fraction at the interface remains virtually unchanged. The interfacial silicide volume fraction is similar. About 58.2 MPa reduced the residual compressive stress of SiC fibers after thermal exposure. In summary, SiCf/Ti60 composites exhibit excellent microstructure, mechanical properties, and thermal stability, enabling long-term operation in a 600 °C vacuum environment.
{"title":"Effect of long-term thermal exposure at 600°C on the tensile properties of SiCf/Ti60 composites","authors":"Zhicong Gan, Yumin Wang, Lina Yang, Qiuyue Jia, Mushi Li, Yuming Zhang, Xu Kong, Rui Yang","doi":"10.1016/j.vacuum.2026.115157","DOIUrl":"10.1016/j.vacuum.2026.115157","url":null,"abstract":"<div><div>In this study, the tensile properties of SiC<sub>f</sub>/Ti60 composites under hot isostatic pressing (HIP) and 600 °C/100h states were investigated. The properties of thermal exposure SiC<sub>f</sub>/Ti60 composites were reduced by about 34 MPa compared to the properties of HIP composites with good thermal stability. The results show that SiC<sub>f</sub>/Ti60 composites have good matrix and interfacial thermal stability. The average grain size of matrix α-Ti in both states was 3.4-3.6 μm, the texture of α-Ti was <0001>//AD and <10-10>//AD, and the polar densities ranged from 6.9 to 7.4 to 2.7-3.1, respectively. The thickness of the interfacial reaction layer in both states was about 0.38-0.43 μm, the interfacial thickness increased slowly, and the silicon content fraction at the interface remains virtually unchanged. The interfacial silicide volume fraction is similar. About 58.2 MPa reduced the residual compressive stress of SiC fibers after thermal exposure. In summary, SiC<sub>f</sub>/Ti60 composites exhibit excellent microstructure, mechanical properties, and thermal stability, enabling long-term operation in a 600 °C vacuum environment.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115157"},"PeriodicalIF":3.9,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174089","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}
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