Pub Date : 2026-04-01Epub Date: 2026-01-07DOI: 10.1016/j.vacuum.2026.115076
Mengmeng Shen , Yulu Yang , Min Wei , Yiwei Liang , Lingwei Wu , Jiahao Ye , Hongyu Chen , Wei Hang
Single-crystal silicon carbide (4H-SiC) is widely recognized for its exceptional physical and chemical properties, which make it an essential material in high-end electronic devices and optoelectronics; however, the challenges posed by its high hardness and chemical inertness complicate the processing of its surface. This study sought to enhance the material removal rate during 4H-SiC surface processing using microwave plasma modification-assisted shear-thickening polishing by focusing on the surface modification rate. The impacts of the microwave irradiation parameters on the surface modification of 4H-SiC were investigated using simulations, orthogonal experiments, and single-factor experiments. The temperature and velocity distributions of the microwave plasma torch were simulated using the COMSOL Multiphysics software, providing valuable theoretical insights. An orthogonal experiment was subsequently conducted to analyze the effects of the microwave power level, Ar flow rate, O2 flow rate, and scanning speed on the surface modification process and inform the determination of the optimal processing conditions. Finally, the results of the orthogonal experiments were validated through single-factor experiments determining that a processing power of 160 W, Ar flow rate of 5500 sccm, O2 flow rate of 8 sccm, scanning speed of 65 mm/min, and scanning grid spacing of 1 mm provided a uniform modified layer with a thickness of 139.59 ± 3.08 nm generated at a remarkable 453.67 ± 10 nm/h. The results of this study offer a theoretical foundation and experimental guidance for improving the microwave plasma modification of 4H-SiC, which is crucial for advancing the application of this material.
{"title":"Optimization of factors influencing microwave plasma modification of single-crystal SiC (0001)","authors":"Mengmeng Shen , Yulu Yang , Min Wei , Yiwei Liang , Lingwei Wu , Jiahao Ye , Hongyu Chen , Wei Hang","doi":"10.1016/j.vacuum.2026.115076","DOIUrl":"10.1016/j.vacuum.2026.115076","url":null,"abstract":"<div><div>Single-crystal silicon carbide (4H-SiC) is widely recognized for its exceptional physical and chemical properties, which make it an essential material in high-end electronic devices and optoelectronics; however, the challenges posed by its high hardness and chemical inertness complicate the processing of its surface. This study sought to enhance the material removal rate during 4H-SiC surface processing using microwave plasma modification-assisted shear-thickening polishing by focusing on the surface modification rate. The impacts of the microwave irradiation parameters on the surface modification of 4H-SiC were investigated using simulations, orthogonal experiments, and single-factor experiments. The temperature and velocity distributions of the microwave plasma torch were simulated using the COMSOL Multiphysics software, providing valuable theoretical insights. An orthogonal experiment was subsequently conducted to analyze the effects of the microwave power level, Ar flow rate, O<sub>2</sub> flow rate, and scanning speed on the surface modification process and inform the determination of the optimal processing conditions. Finally, the results of the orthogonal experiments were validated through single-factor experiments determining that a processing power of 160 W, Ar flow rate of 5500 sccm, O<sub>2</sub> flow rate of 8 sccm, scanning speed of 65 mm/min, and scanning grid spacing of 1 mm provided a uniform modified layer with a thickness of 139.59 ± 3.08 nm generated at a remarkable 453.67 ± 10 nm/h. The results of this study offer a theoretical foundation and experimental guidance for improving the microwave plasma modification of 4H-SiC, which is crucial for advancing the application of this material.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115076"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026004","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 : 2026-04-01Epub Date: 2026-01-16DOI: 10.1016/j.vacuum.2026.115100
George Tzvetkov, Nina Kaneva, Evelina Vassileva, Tony Spassov
Novel hierarchically-structured ZnO microflowers (<5 μm) have been successfully prepared via rapid drop-by-drop precipitation method. The as-prepared microstructures possess high crystallinity, surface area of 24 m2g-1 and optical band gap of 3.29 ± 0.03 eV. Also, they demonstrated intense yellow-green photoluminescence emission at room temperature, due to the abundant oxygen vacancy defects (VO, VO+ and VO++). The tribocatalytic properties of the microflowers were evaluated through degradation of Ciprofloxacin antibiotic at dark conditions. The as-prepared material showed very favorable catalytic activity, which led to 91.6 ± 1.1 % degradation of the pollutant within 480 min in typical pseudo-first-order kinetics. Scavenger tests identified superoxide radicals as the main active species in the catalytic process. Finally, ZnO microflowers displayed good recyclability, maintaining 90.2 ± 1.9 % drug degradation over three cycles. The ZnO microarchitectures observed in this work are considered as a promising cost-effective and environmentally benign material for future optoelectronic and tribocatalytic applications.
{"title":"Polygons-assembled ZnO flower-like microparticles: easy fabrication, photoluminescence and tribocatalytic properties","authors":"George Tzvetkov, Nina Kaneva, Evelina Vassileva, Tony Spassov","doi":"10.1016/j.vacuum.2026.115100","DOIUrl":"10.1016/j.vacuum.2026.115100","url":null,"abstract":"<div><div>Novel hierarchically-structured ZnO microflowers (<5 μm) have been successfully prepared via rapid drop-by-drop precipitation method. The as-prepared microstructures possess high crystallinity, surface area of 24 m<sup>2</sup>g<sup>-1</sup> and optical band gap of 3.29 ± 0.03 eV. Also, they demonstrated intense yellow-green photoluminescence emission at room temperature, due to the abundant oxygen vacancy defects (V<sub>O</sub>, V<sub>O</sub><sup>+</sup> and V<sub>O</sub><sup>++</sup>). The tribocatalytic properties of the microflowers were evaluated through degradation of Ciprofloxacin antibiotic at dark conditions. The as-prepared material showed very favorable catalytic activity, which led to 91.6 ± 1.1 % degradation of the pollutant within 480 min in typical pseudo-first-order kinetics. Scavenger tests identified superoxide radicals as the main active species in the catalytic process. Finally, ZnO microflowers displayed good recyclability, maintaining 90.2 ± 1.9 % drug degradation over three cycles. The ZnO microarchitectures observed in this work are considered as a promising cost-effective and environmentally benign material for future optoelectronic and tribocatalytic applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115100"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026002","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 : 2026-04-01Epub Date: 2026-01-28DOI: 10.1016/j.vacuum.2026.115141
Yue Wang , Chaofeng Sang , Jintao Wu , Nami Li , Yu Bian , Changjiang Sun , Mingzhou Zhang , Chen Zhang , Yao Peng , Chongyang Jin , Yue Tian , Dezhen Wang
Linear plasma devices (LPDs) are important experimental platforms for investigating plasma–material interactions (PMI). In PMI experiments, it has been found that applying a target bias not only effectively modifies the incident ion energy, but also induces significant changes in the electron density and electron temperature, whereby the evolution of these plasma parameters is primarily governed by plasma transport processes. However, at present, the physical process and mechanism underlying such bias-induced variations remain unclear. In this work, biasing experiments under argon plasma discharge conditions were first carried out on the MPS-LD device. For the corresponding experiments, an electric potential model was newly developed based on the BOUT++ LPD module, enabling self-consistent simulations of plasma transport under biased conditions. Numerical simulations were then performed to reproduce the experimental results and to validate the accuracy of the proposed model. Finally, by combining experimental measurements with numerical simulations, a bias-voltage scan was performed to investigate how the electron density and electron temperature vary with the bias voltage (Ubias). The results show that applying negative bias decreases the target electron density (ne,T) while increasing the target electron temperature (Te,T). In contrast, positive bias increases both ne,T and Te,T; however, at high positive bias, ne,T first reaches a maximum and subsequently decreases with further increases in Ubias. The underlying physical mechanisms are analyzed using particle flux, momentum, and energy conservation. It indicates that the applied bias regulates the parallel electric field, thereby changing ion and electron velocities, and consequently affecting the electron density. At high positive bias, the ion velocity is further influenced by ion viscosity, leading to the reversal in ne,T. Meanwhile, the enhanced parallel electric field drives stronger currents, significantly increasing ion–electron frictional work and converting the input bias power into electron energy, which raises the electron temperature. These results contribute to a deeper understanding of the effects and mechanisms of biasing on plasma transport in the MPS-LD device.
{"title":"Experimental and simulation study of target biasing effects on plasma transport in linear plasma device MPS-LD","authors":"Yue Wang , Chaofeng Sang , Jintao Wu , Nami Li , Yu Bian , Changjiang Sun , Mingzhou Zhang , Chen Zhang , Yao Peng , Chongyang Jin , Yue Tian , Dezhen Wang","doi":"10.1016/j.vacuum.2026.115141","DOIUrl":"10.1016/j.vacuum.2026.115141","url":null,"abstract":"<div><div>Linear plasma devices (LPDs) are important experimental platforms for investigating plasma–material interactions (PMI). In PMI experiments, it has been found that applying a target bias not only effectively modifies the incident ion energy, but also induces significant changes in the electron density and electron temperature, whereby the evolution of these plasma parameters is primarily governed by plasma transport processes. However, at present, the physical process and mechanism underlying such bias-induced variations remain unclear. In this work, biasing experiments under argon plasma discharge conditions were first carried out on the MPS-LD device. For the corresponding experiments, an electric potential model was newly developed based on the BOUT++ LPD module, enabling self-consistent simulations of plasma transport under biased conditions. Numerical simulations were then performed to reproduce the experimental results and to validate the accuracy of the proposed model. Finally, by combining experimental measurements with numerical simulations, a bias-voltage scan was performed to investigate how the electron density and electron temperature vary with the bias voltage (<em>U</em><sub><em>bias</em></sub>). The results show that applying negative bias decreases the target electron density (<em>n</em><sub><em>e,T</em></sub>) while increasing the target electron temperature (<em>T</em><sub><em>e,T</em></sub>). In contrast, positive bias increases both <em>n</em><sub><em>e,T</em></sub> and <em>T</em><sub><em>e,T</em></sub>; however, at high positive bias, <em>n</em><sub><em>e,T</em></sub> first reaches a maximum and subsequently decreases with further increases in <em>U</em><sub><em>bias</em></sub>. The underlying physical mechanisms are analyzed using particle flux, momentum, and energy conservation. It indicates that the applied bias regulates the parallel electric field, thereby changing ion and electron velocities, and consequently affecting the electron density. At high positive bias, the ion velocity is further influenced by ion viscosity, leading to the reversal in <em>n</em><sub><em>e,T</em></sub>. Meanwhile, the enhanced parallel electric field drives stronger currents, significantly increasing ion–electron frictional work and converting the input bias power into electron energy, which raises the electron temperature. These results contribute to a deeper understanding of the effects and mechanisms of biasing on plasma transport in the MPS-LD device.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115141"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174070","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 : 2026-04-01Epub Date: 2026-02-09DOI: 10.1016/j.vacuum.2026.115168
Wen-Rui Li , Hao-Yan Liu , Guang-Yu Sun , Yu-Cheng Zhang , Chang-Chun Qi , Xiao-Gang Qin , Bai-Peng Song , Guan-Jun Zhang
In vacuum-dielectric insulation systems, the interface where dielectric is in contact with vacuum is a weak point of insulation, and the frequent occurrence of surface flashover poses a threat to the safe operation of the system. This study proposes a novel approach to mitigate flashover by constructing micron-scale pores on polyimide (PI) surfaces, fabricating films with surface pore diameters of 3.8 ± 0.9 μm, 6.0 ± 1.3 μm, 9.8 ± 2.8 μm, and 11.0 ± 3.6 μm. Experimental results demonstrate PI films with surface micron pores exhibit significantly improved flashover thresholds and a notable reduction in secondary electron yield (SEY). When the pore diameter is 11.0 ± 3.6 μm, the DC and impulse flashover thresholds increase by up to ∼79% and ∼187%, respectively, while the maximum SEY (δmax) decreases to 1.32. Particle-in-cell (PIC) simulations further validate the inhibitory effect on multipactor. It is observed that electrons are guided into pores during movement and ultimately trapped, significantly slowing down the electron avalanche development, reducing the rate of increase in average surface charge density. The electric field configuration within the pores and pore geometry facilitates the capture of electrons. This study provides an in-depth understanding of the mechanism by which surface micron-scale pores suppress multipactor and alleviate flashover, offering valuable guidance for addressing flashover problems.
{"title":"Polyimide films featuring surface micron-scale pores for superior multipactor inhibition","authors":"Wen-Rui Li , Hao-Yan Liu , Guang-Yu Sun , Yu-Cheng Zhang , Chang-Chun Qi , Xiao-Gang Qin , Bai-Peng Song , Guan-Jun Zhang","doi":"10.1016/j.vacuum.2026.115168","DOIUrl":"10.1016/j.vacuum.2026.115168","url":null,"abstract":"<div><div>In vacuum-dielectric insulation systems, the interface where dielectric is in contact with vacuum is a weak point of insulation, and the frequent occurrence of surface flashover poses a threat to the safe operation of the system. This study proposes a novel approach to mitigate flashover by constructing micron-scale pores on polyimide (PI) surfaces, fabricating films with surface pore diameters of 3.8 ± 0.9 μm, 6.0 ± 1.3 μm, 9.8 ± 2.8 μm, and 11.0 ± 3.6 μm. Experimental results demonstrate PI films with surface micron pores exhibit significantly improved flashover thresholds and a notable reduction in secondary electron yield (SEY). When the pore diameter is 11.0 ± 3.6 μm, the DC and impulse flashover thresholds increase by up to ∼79% and ∼187%, respectively, while the maximum SEY (<em>δ</em><sub><em>max</em></sub>) decreases to 1.32. Particle-in-cell (PIC) simulations further validate the inhibitory effect on multipactor. It is observed that electrons are guided into pores during movement and ultimately trapped, significantly slowing down the electron avalanche development, reducing the rate of increase in average surface charge density. The electric field configuration within the pores and pore geometry facilitates the capture of electrons. This study provides an in-depth understanding of the mechanism by which surface micron-scale pores suppress multipactor and alleviate flashover, offering valuable guidance for addressing flashover problems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115168"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174110","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 : 2026-04-01Epub 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":"2026-04-01","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}
The dielectric strength of high-voltage vacuum gaps is a critical issue in the development and operation of high-power electrophysical devices. It is well known that the onset of a significant field-emission current from the vacuum gap cathode precedes vacuum breakdown. In this study, we investigate the correlation between the static vacuum breakdown voltage and the cathode's field emission properties. We examined a pure copper cathode with dimensions on the order of tens of micrometers. A series of sequential field-emission current-voltage measurements and vacuum breakdown tests were conducted. Additionally, the field-emission orthodoxy factor was calculated. For different cathode surface states, we obtained sets of local electric field enhancement factors, β, emission orthodoxy factors, and breakdown voltages. Assuming a specific breakdown electric field strength and using the determined β values, we estimated breakdown voltage values and compared these with experimentally measured ones. Our analysis revealed that within a particular range of the field-emission orthodoxy factor, the corresponding β values allowed the estimation of the breakdown voltage with approximately 10 % error. These results suggest that it is possible to develop an approach for predicting static vacuum breakdown voltage based solely on the field emission properties of the cathode.
{"title":"The dependence of vacuum gap breakdown voltage on field emission properties","authors":"S.A. Barengolts , Yu.I. Mamontov , I.V. Uimanov , Yu.A. Zemskov","doi":"10.1016/j.vacuum.2026.115107","DOIUrl":"10.1016/j.vacuum.2026.115107","url":null,"abstract":"<div><div>The dielectric strength of high-voltage vacuum gaps is a critical issue in the development and operation of high-power electrophysical devices. It is well known that the onset of a significant field-emission current from the vacuum gap cathode precedes vacuum breakdown. In this study, we investigate the correlation between the static vacuum breakdown voltage and the cathode's field emission properties. We examined a pure copper cathode with dimensions on the order of tens of micrometers. A series of sequential field-emission current-voltage measurements and vacuum breakdown tests were conducted. Additionally, the field-emission orthodoxy factor was calculated. For different cathode surface states, we obtained sets of local electric field enhancement factors, <em>β</em>, emission orthodoxy factors, and breakdown voltages. Assuming a specific breakdown electric field strength and using the determined <em>β</em> values, we estimated breakdown voltage values and compared these with experimentally measured ones. Our analysis revealed that within a particular range of the field-emission orthodoxy factor, the corresponding <em>β</em> values allowed the estimation of the breakdown voltage with approximately 10 % error. These results suggest that it is possible to develop an approach for predicting static vacuum breakdown voltage based solely on the field emission properties of the cathode.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115107"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080121","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 : 2026-04-01Epub Date: 2026-01-20DOI: 10.1016/j.vacuum.2026.115116
Yuhang Chen , Jie Li , Chao Pan , Ruili Ma , Jidong Long , Xiaozhong He , Jinshui Shi , Kefu Liu
High-power, compact, built-in Penning negative hydrogen ion source has been widely used in particle accelerator applications. But the problem of its short operating life has been an issue, with cathode mass loss being the main factor affecting its life. The material lost from the cathode will condense on the anode wall and will flake off under alternating heat and cold. The flaking material is directed from the cathode to the anode under the action of an electric field, and when the debris is too large it will short-circuit the cathode and anode directly. To solve this key problem, it is necessary to study the specific causes of cathode mass loss, and optimize the operation methods and design ideas of the ion source through these causes. In this paper, the cathode mass loss mechanism was investigated. It is considered that the cathode mass of this ion source is mainly lost through the evaporation process during the large arc current operation under the high purity gas environment. And several optimization measures are proposed in the operation and design of the equipment.
{"title":"Study on the principle of mass loss of Penning Negative ion source cathode","authors":"Yuhang Chen , Jie Li , Chao Pan , Ruili Ma , Jidong Long , Xiaozhong He , Jinshui Shi , Kefu Liu","doi":"10.1016/j.vacuum.2026.115116","DOIUrl":"10.1016/j.vacuum.2026.115116","url":null,"abstract":"<div><div>High-power, compact, built-in Penning negative hydrogen ion source has been widely used in particle accelerator applications. But the problem of its short operating life has been an issue, with cathode mass loss being the main factor affecting its life. The material lost from the cathode will condense on the anode wall and will flake off under alternating heat and cold. The flaking material is directed from the cathode to the anode under the action of an electric field, and when the debris is too large it will short-circuit the cathode and anode directly. To solve this key problem, it is necessary to study the specific causes of cathode mass loss, and optimize the operation methods and design ideas of the ion source through these causes. In this paper, the cathode mass loss mechanism was investigated. It is considered that the cathode mass of this ion source is mainly lost through the evaporation process during the large arc current operation under the high purity gas environment. And several optimization measures are proposed in the operation and design of the equipment.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115116"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080216","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 : 2026-04-01Epub Date: 2026-01-19DOI: 10.1016/j.vacuum.2026.115101
Ruyin Deng , Yanshu Huang , Shisong Liu , Jichuan Huo , Yong Cao
In this study, to our knowledge, this is the first systematic demonstration of a room-temperature to 200 °C PTCR window in La-doped LiTaO3 with grain-boundary-dominated barriers. The results show that the solubility of La in LiTaO3 was less than 15 wt%, and the La contents would affect the microstructure as well the electrical conductivity of LiTaO3. For the LiTaO3-based materials with/without La doping, the materials exhibit the PTCR jump (log (Rmax/Rmin)) of 2.6–3.6 between room temperature and ∼200 °C, and varied with La contents. By combining impedance spectroscopy and time relaxation techniques, the complex impedance response of LiTaO3-based ceramic materials was analyzed, revealing multiple grain boundary resistances corresponding to relaxation processes with distinct time constants (τ) were the origin of the PTC effect.
{"title":"Grain boundary engineering and positive temperature coefficient of resistance behavior in La3+-doped LiTaO3 lead-free ceramics","authors":"Ruyin Deng , Yanshu Huang , Shisong Liu , Jichuan Huo , Yong Cao","doi":"10.1016/j.vacuum.2026.115101","DOIUrl":"10.1016/j.vacuum.2026.115101","url":null,"abstract":"<div><div>In this study, to our knowledge, this is the first systematic demonstration of a room-temperature to 200 °C PTCR window in La-doped LiTaO<sub>3</sub> with grain-boundary-dominated barriers. The results show that the solubility of La in LiTaO<sub>3</sub> was less than 15 wt%, and the La contents would affect the microstructure as well the electrical conductivity of LiTaO<sub>3</sub>. For the LiTaO<sub>3</sub>-based materials with/without La doping, the materials exhibit the PTCR jump (log (R<sub>max</sub>/R<sub>min</sub>)) of 2.6–3.6 between room temperature and ∼200 °C, and varied with La contents. By combining impedance spectroscopy and time relaxation techniques, the complex impedance response of LiTaO<sub>3</sub>-based ceramic materials was analyzed, revealing multiple grain boundary resistances corresponding to relaxation processes with distinct time constants (τ) were the origin of the PTC effect.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115101"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025499","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 : 2026-04-01Epub Date: 2026-01-20DOI: 10.1016/j.vacuum.2026.115105
Zhan-Xing Li, Wen-Qian Wang, Peng Dou
FeCrAl oxide dispersion strengthened (ODS) steel is a promising candidate cladding material for Generation IV nuclear reactors due to its excellent resistance to creep, irradiation, oxidation, and corrosion. The thermal stability of matrix grains and, moreover, the phase, dispersion morphology and metal/oxide interface structure of nanoparticles in 16Cr–2Al–0.1Ti–0.35Ce–0.35Y2O3 (wt. %) ODS steel aged at 700 °C for 10,000 h was investigated using S/TEM and HRTEM. After aging, the matrix grain size increased from 1.0 μm to 1.1 μm. For the nanoparticles, the mean diameter changed from 8.9 nm to 9.3 nm; the number density decreased from 5.9 × 1021 m−3 to 5.5 × 1021 m−3, and the inter-particle spacing increased from 139.5 nm to 140.7 nm. The proportion of Y–Ce–O oxides changed slightly from 52.2 % to 55.3 %, while that of Y–Ti–O changed from 22.1 % to 21.3 %. The proportion of coherent/semi-coherent particles changed from 88.6 % to 90.7 %. The nano-mesoscopic structure exhibited no significant changes, demonstrating its excellent thermal stability. Owing to the stable nano-mesoscopic structure, the Vickers hardness decreased only slightly from 275 HV to 263 HV. The origins of the thermal stability of the nano-mesoscopic structure were discussed in terms of Ostwald ripening, diffusion behavior, Zener pinning, and strengthening mechanisms.
{"title":"Thermal stability of nano-mesoscopic structure in Ce-Added FeCrAl ODS steel aged at 700 °C for 10,000 h","authors":"Zhan-Xing Li, Wen-Qian Wang, Peng Dou","doi":"10.1016/j.vacuum.2026.115105","DOIUrl":"10.1016/j.vacuum.2026.115105","url":null,"abstract":"<div><div>FeCrAl oxide dispersion strengthened (ODS) steel is a promising candidate cladding material for Generation IV nuclear reactors due to its excellent resistance to creep, irradiation, oxidation, and corrosion. The thermal stability of matrix grains and, moreover, the phase, dispersion morphology and metal/oxide interface structure of nanoparticles in 16Cr–2Al–0.1Ti–0.35Ce–0.35Y<sub>2</sub>O<sub>3</sub> (wt. %) ODS steel aged at 700 °C for 10,000 h was investigated using S/TEM and HRTEM. After aging, the matrix grain size increased from 1.0 μm to 1.1 μm. For the nanoparticles, the mean diameter changed from 8.9 nm to 9.3 nm; the number density decreased from 5.9 × 10<sup>21</sup> m<sup>−3</sup> to 5.5 × 10<sup>21</sup> m<sup>−3</sup>, and the inter-particle spacing increased from 139.5 nm to 140.7 nm. The proportion of Y–Ce–O oxides changed slightly from 52.2 % to 55.3 %, while that of Y–Ti–O changed from 22.1 % to 21.3 %. The proportion of coherent/semi-coherent particles changed from 88.6 % to 90.7 %. The nano-mesoscopic structure exhibited no significant changes, demonstrating its excellent thermal stability. Owing to the stable nano-mesoscopic structure, the Vickers hardness decreased only slightly from 275 HV to 263 HV. The origins of the thermal stability of the nano-mesoscopic structure were discussed in terms of Ostwald ripening, diffusion behavior, Zener pinning, and strengthening mechanisms.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115105"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146025497","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}
Si-doped WO3 films with Pd surface decoration were deposited by RF magnetron sputtering for isoprene sensing. A few decoration processes were attempted to achieve best sensing performance. Although Pd decoration induced a negligible change in X-ray diffraction patterns, a variation in band gap was observed, due to an increased number of oxygen vacancies in the films as revealed by X-ray photoelectron spectroscopy, which also indicated that Pd was partially oxidized. Transmission electron microscopy confirmed that the film surface was covered by a layer of Pd nanoparticles, which had the Pd/PdO core-shell nanostructure with a size of 5-10 nm. Si-doped WO3 films with 0.64/1 Pd decoration exhibited excellent isoprene response, measuring 43.8 for 5 ppm isoprene and 8.03 for 0.7 ppm isoprene at a working temperature of 350 °C. The films showed an extremely short isoprene response time of about 0.4 s. Moreover, the films showed a good selectivity, with the sensor response of isoprene being 2.3, 7.0, 7.4, 16.9, and 20.6 times higher than that of ethanol, methanol, acetone, CO2, and CO, respectively.
{"title":"Greatly increased isoprene sensitivity by Pd surface decoration of Si-doped tungsten oxide films","authors":"Yue-Chi Chen , Hai-Yun Chuang , You-Peng Chen , Xiaoding Qi , Liji Huang","doi":"10.1016/j.vacuum.2026.115177","DOIUrl":"10.1016/j.vacuum.2026.115177","url":null,"abstract":"<div><div>Si-doped WO<sub>3</sub> films with Pd surface decoration were deposited by RF magnetron sputtering for isoprene sensing. A few decoration processes were attempted to achieve best sensing performance. Although Pd decoration induced a negligible change in X-ray diffraction patterns, a variation in band gap was observed, due to an increased number of oxygen vacancies in the films as revealed by X-ray photoelectron spectroscopy, which also indicated that Pd was partially oxidized. Transmission electron microscopy confirmed that the film surface was covered by a layer of Pd nanoparticles, which had the Pd/PdO core-shell nanostructure with a size of 5-10 nm. Si-doped WO<sub>3</sub> films with 0.64/1 Pd decoration exhibited excellent isoprene response, measuring 43.8 for 5 ppm isoprene and 8.03 for 0.7 ppm isoprene at a working temperature of 350 °C. The films showed an extremely short isoprene response time of about 0.4 s. Moreover, the films showed a good selectivity, with the sensor response of isoprene being 2.3, 7.0, 7.4, 16.9, and 20.6 times higher than that of ethanol, methanol, acetone, CO<sub>2</sub>, and CO, respectively.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115177"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174109","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号