Pub 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":"2026-01-19","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}
A novel intersecting-axis meshing Quimby-tooth dry screw vacuum pump was proposed in this paper. The mathematical model for generating the geometric structure of intersecting-axis meshing Quimby-tooth screw rotors is established, alongside a geometric characteristic calculation model for this novel screw structure. Two basic design methods for the intersecting-axis meshing Quimby-tooth screw structure are proposed, and their geometric characteristics are analyzed by comparing them with conventional parallel-axis meshing screw rotors, thus revealing the technical potential of this new technology. The proposed geometry generation model is verified by fabricating a prototype of the intersecting-axis meshing screw vacuum pump via 3D printing, while the geometric characteristic analysis model is validated using commercial software. Research results show that intersecting-axis meshing technology can reduce rotor volume by 24 %, leakage channel length by 32 %, and gear meshing velocity by 44.5 %. This study provides fundamental references and insights for the development of next-generation dry screw vacuum pumps, further advancing progress in vacuum acquisition fields.
{"title":"Design of a novel intersecting-axis meshing Quimby-tooth dry screw vacuum pump","authors":"Dantong Li, Xiaoqian Chen, Kai Ma, Chongzhou Sun, Zhilong He, Chuang Wang, Ziwen Xing","doi":"10.1016/j.vacuum.2026.115121","DOIUrl":"10.1016/j.vacuum.2026.115121","url":null,"abstract":"<div><div>A novel intersecting-axis meshing Quimby-tooth dry screw vacuum pump was proposed in this paper. The mathematical model for generating the geometric structure of intersecting-axis meshing Quimby-tooth screw rotors is established, alongside a geometric characteristic calculation model for this novel screw structure. Two basic design methods for the intersecting-axis meshing Quimby-tooth screw structure are proposed, and their geometric characteristics are analyzed by comparing them with conventional parallel-axis meshing screw rotors, thus revealing the technical potential of this new technology. The proposed geometry generation model is verified by fabricating a prototype of the intersecting-axis meshing screw vacuum pump via 3D printing, while the geometric characteristic analysis model is validated using commercial software. Research results show that intersecting-axis meshing technology can reduce rotor volume by 24 %, leakage channel length by 32 %, and gear meshing velocity by 44.5 %. This study provides fundamental references and insights for the development of next-generation dry screw vacuum pumps, further advancing progress in vacuum acquisition fields.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115121"},"PeriodicalIF":3.9,"publicationDate":"2026-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174104","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 : 2026-01-17DOI: 10.1016/j.vacuum.2026.115104
Jiarong Li , Jinbo Zhai , Guozheng Zha , Wenlong Jiang , Baoqiang Xu , Dachun Liu , Bin Yang
Arsenic (As), commonly present in sulfides, oxides, and metal compounds like copper, cobalt, nickel, and lead, poses significant environmental and health hazards. Effective arsenic waste management is essential for pollution control and resource recovery. While vacuum distillation and graded condensation have been studied individually, this study introduces an integrated approach that combines single-step vacuum distillation with a multistage fractional condensation system based on molecular mean free path (MFP) principles. This method enables simultaneous recovery of elemental arsenic and enrichment of lead (Pb), bismuth (Bi), and silver (Ag) from highly toxic waste. By aligning condenser spacing with arsenic's MFP, the system enhances selective volatilization, differing from earlier empirical or single-stage designs. The approach was validated through theoretical analysis, CFD simulations, and experiments. At 500 °C and 10 Pa for 60 min, it achieved 99.1 % pure crude arsenic recovery, increased lead content from 37.55 % to 72.2 %, and reached 97.82 % arsenic removal efficiency. CFD results revealed detailed temperature and vapor flow patterns, closely matching experimental outcomes and confirming effectiveness. This clean, one-step process provides an economically feasible solution for arsenic removal and valuable metal concentration, with potential applicability to other complex waste streams.
{"title":"One-step to extract elemental arsenic from highly toxic hazardous arsenic waste","authors":"Jiarong Li , Jinbo Zhai , Guozheng Zha , Wenlong Jiang , Baoqiang Xu , Dachun Liu , Bin Yang","doi":"10.1016/j.vacuum.2026.115104","DOIUrl":"10.1016/j.vacuum.2026.115104","url":null,"abstract":"<div><div>Arsenic (As), commonly present in sulfides, oxides, and metal compounds like copper, cobalt, nickel, and lead, poses significant environmental and health hazards. Effective arsenic waste management is essential for pollution control and resource recovery. While vacuum distillation and graded condensation have been studied individually, this study introduces an integrated approach that combines single-step vacuum distillation with a multistage fractional condensation system based on molecular mean free path (MFP) principles. This method enables simultaneous recovery of elemental arsenic and enrichment of lead (Pb), bismuth (Bi), and silver (Ag) from highly toxic waste. By aligning condenser spacing with arsenic's MFP, the system enhances selective volatilization, differing from earlier empirical or single-stage designs. The approach was validated through theoretical analysis, CFD simulations, and experiments. At 500 °C and 10 Pa for 60 min, it achieved 99.1 % pure crude arsenic recovery, increased lead content from 37.55 % to 72.2 %, and reached 97.82 % arsenic removal efficiency. CFD results revealed detailed temperature and vapor flow patterns, closely matching experimental outcomes and confirming effectiveness. This clean, one-step process provides an economically feasible solution for arsenic removal and valuable metal concentration, with potential applicability to other complex waste streams.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115104"},"PeriodicalIF":3.9,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026001","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}
Electroadhesion exhibits exceptional environmental adaptability and precise controllability, making it highly promising for space applications such as robotic manipulators, orbital debris capture, and on-orbit satellite servicing. Nevertheless, the fundamental adhesion mechanisms under high-vacuum electron irradiation remain inadequately characterized, and the electron charging effect may adversely impact the electroadhesive force, which severely limits its implementation in extraterrestrial environment. This study employs dielectric polarization theory coupled with three-dimensional particle-in-cell (PIC) simulations to demonstrate that incident electrons deposit only in the superficial layer (≤2 μm depth) of dielectric coatings and target substrates, with negligible penetration to actuation electrodes. Such localized deposition induces minimal variations in interfacial potential (ΔV < 45 V) and electrostatic field distribution (variation <5.2 %), thereby preserving electroadhesive functionality. Experimental validation under simulated space conditions (electron energy: 10 keV) in a high-vacuum chamber (base pressure: 10−4 Pa) reveals: a) Consistent operational integrity of the electroadhesion pad (EA pad); b) Sustained adhesive force stability (>0.3 N/cm2) with minimal fluctuation (<11 %). These findings establish critical criteria for electroadhesion in space applications.
{"title":"Intact electroadhesive performance under 10 keV electron irradiation in high vacuum","authors":"Wenhe Liao , Bingrui Li , Wei Tian , Jinjun Duan , Jiaming Zhang , Yunfei Miao , Zhengwei Wang , Zichao Chen","doi":"10.1016/j.vacuum.2026.115098","DOIUrl":"10.1016/j.vacuum.2026.115098","url":null,"abstract":"<div><div>Electroadhesion exhibits exceptional environmental adaptability and precise controllability, making it highly promising for space applications such as robotic manipulators, orbital debris capture, and on-orbit satellite servicing. Nevertheless, the fundamental adhesion mechanisms under high-vacuum electron irradiation remain inadequately characterized, and the electron charging effect may adversely impact the electroadhesive force, which severely limits its implementation in extraterrestrial environment. This study employs dielectric polarization theory coupled with three-dimensional particle-in-cell (PIC) simulations to demonstrate that incident electrons deposit only in the superficial layer (≤2 μm depth) of dielectric coatings and target substrates, with negligible penetration to actuation electrodes. Such localized deposition induces minimal variations in interfacial potential (ΔV < 45 V) and electrostatic field distribution (variation <5.2 %), thereby preserving electroadhesive functionality. Experimental validation under simulated space conditions (electron energy: 10 keV) in a high-vacuum chamber (base pressure: 10<sup>−4</sup> Pa) reveals: a) Consistent operational integrity of the electroadhesion pad (EA pad); b) Sustained adhesive force stability (>0.3 N/cm<sup>2</sup>) with minimal fluctuation (<11 %). These findings establish critical criteria for electroadhesion in space applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115098"},"PeriodicalIF":3.9,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026015","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}
Heterostructures, particularly dual-phase heterostructures, often lead to hetero-interfacial stress concentration, and ultimately premature failure, though they benefit from heterogeneous deformation. Addressing the challenge of strain localization and hetero-interfacial cracking, a single-phase heterogeneous grain structure is designed through tuning zirconium (Zr) content and employing precise thermo-mechanical treatment. As Zr content increases to 0.50 wt %, a single-phase bimodal grain structure is successfully engineered, including soft coarse grain zones (∼5 μm in size and 65 % in area) and hard fine grain zones (∼1 μm in size and 35 % in area). Such bimodal heterostructure is mainly ascribed to the retarding effect of recrystallization, due to the drag effect of Zr atoms and Zener pinning of ZrC. The synergistic effects of microstructural heterogeneity and ZrC precipitation enhance the strengths. Furthermore, multistage deformation mechanisms, involving heterogeneous deformation-induced hardening, dislocation slip and nanotwinning, enable the strain hardening capability and ductility.
{"title":"Promoting strength-ductility synergy by heterogeneous grain structure in a zirconium-alloyed Fe-Mn-Al-C low-density steel","authors":"Yuheng Wang, Runze Yu, Fengchao An, Suotao Wang, Hao Wang, Zibo Zhao, Hongpu Yue, Tianxiang Gao, Junting Luo, Junsong Zhang, Riping Liu","doi":"10.1016/j.vacuum.2026.115094","DOIUrl":"10.1016/j.vacuum.2026.115094","url":null,"abstract":"<div><div>Heterostructures, particularly dual-phase heterostructures, often lead to hetero-interfacial stress concentration, and ultimately premature failure, though they benefit from heterogeneous deformation. Addressing the challenge of strain localization and hetero-interfacial cracking, a single-phase heterogeneous grain structure is designed through tuning zirconium (Zr) content and employing precise thermo-mechanical treatment. As Zr content increases to 0.50 wt %, a single-phase bimodal grain structure is successfully engineered, including soft coarse grain zones (∼5 μm in size and 65 % in area) and hard fine grain zones (∼1 μm in size and 35 % in area). Such bimodal heterostructure is mainly ascribed to the retarding effect of recrystallization, due to the drag effect of Zr atoms and Zener pinning of ZrC. The synergistic effects of microstructural heterogeneity and ZrC precipitation enhance the strengths. Furthermore, multistage deformation mechanisms, involving heterogeneous deformation-induced hardening, dislocation slip and nanotwinning, enable the strain hardening capability and ductility.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"246 ","pages":"Article 115094"},"PeriodicalIF":3.9,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977650","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}
Due to the relatively low strength and plasticity of magnesium alloy welding joints, RE elements can enhance the strength and plasticity of magnesium alloys. Based on this, a rolled-state Mg-5Al-2Gd-0.5Mn rare earth magnesium alloy was developed and welded using pulsed laser welding technology. The research results indicate that the tensile strength reaches as high as 263.5 MPa, the fracture type is ductile fracture. Inside the grains, the main phase is the sub - micron - sized Al2Gd phase. Near the grain boundaries, it is mainly the nano - sized Al8Mn4Gd phase, and at the grain boundaries, both phases coexist. During the growth process of the rare – earth (RE) phases, the intra - granular RE phases act as heterogeneous nucleation sites, and the grain - boundary RE phases absorb the Mg17Al12 phase to form a polycrystalline phase at the grain boundaries. Their combined effect refines the grains. After forming, the intra - granular RE phases connect to form a strong pinning effect, which hinders the dislocation slip and shares more stress for the matrix. Meanwhile, the RE phases at the grain boundaries reduce the segregation of impurities and strengthen the grain boundaries.
{"title":"Study on the rare earth phases, crystal textures and mechanical properties of pulsed laser welded Mg-5Al-2Gd-0.5Mn alloy weld","authors":"Bangfu Zhang , Xiaobin Zhang , Pengfei Zhao , Shuwang Bian , Kanglin Ke , Weifeng Xie","doi":"10.1016/j.vacuum.2026.115099","DOIUrl":"10.1016/j.vacuum.2026.115099","url":null,"abstract":"<div><div>Due to the relatively low strength and plasticity of magnesium alloy welding joints, RE elements can enhance the strength and plasticity of magnesium alloys. Based on this, a rolled-state Mg-5Al-2Gd-0.5Mn rare earth magnesium alloy was developed and welded using pulsed laser welding technology. The research results indicate that the tensile strength reaches as high as 263.5 MPa, the fracture type is ductile fracture. Inside the grains, the main phase is the sub - micron - sized Al<sub>2</sub>Gd phase. Near the grain boundaries, it is mainly the nano - sized Al<sub>8</sub>Mn<sub>4</sub>Gd phase, and at the grain boundaries, both phases coexist. During the growth process of the rare – earth (RE) phases, the intra - granular RE phases act as heterogeneous nucleation sites, and the grain - boundary RE phases absorb the Mg<sub>17</sub>Al<sub>12</sub> phase to form a polycrystalline phase at the grain boundaries. Their combined effect refines the grains. After forming, the intra - granular RE phases connect to form a strong pinning effect, which hinders the dislocation slip and shares more stress for the matrix. Meanwhile, the RE phases at the grain boundaries reduce the segregation of impurities and strengthen the grain boundaries.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"246 ","pages":"Article 115099"},"PeriodicalIF":3.9,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977729","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 : 2026-01-16DOI: 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":"2026-01-16","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}
Mo2TiAlC2 is a novel MAX phase. Generally, the synthesis of Mo2TiAlC2 require Ti powders as Ti source. In this paper, TiC powders were used as Ti source to synthesize highly pure Mo2TiAlC2, at 1500 °C for 72 h or at 1600 °C for 3 h. As the Ti source, TiC can directly participate in the formation reaction, significantly improving the reaction kinetics, effectively lowering the synthesis temperature, and enabling the successful preparation of single-phase Mo2TiAlC2 at 1500 °C. Thereafter, the oxidation resistance of Mo2TiAlC2 was characterized. Based on thermal analysis, the oxidation of Mo2TiAlC2 proceeds in three distinct steps: first, partial oxidation of Mo2TiAlC2 initiates at 420 °C, generating MoO3, Al2(MoO4)3, and TiC; subsequently, between 520 °C and 715 °C, Mo2TiAlC2 and the TiC formed in first step are completely oxidized, yielding MoO3, Al2(MoO4)3, and TiO2; finally, above 870 °C, Al2(MoO4)3 decomposes and MoO3 are volatized, resulting in TiO2 and Al2O3 as the final oxidation products. The unique oxidation intermediates—MoO3, Al2(MoO4)3, and TiC—endow Mo2TiAlC2 with significant potential for applications in the field of tribology.
{"title":"The synthesis and oxidation resistance of Mo2TiAlC2 with TiC as Ti source","authors":"Bin Zhang, Yibo Di, Miao Zhang, Yukai Chang, Libo Wang, Aiguo Zhou","doi":"10.1016/j.vacuum.2026.115097","DOIUrl":"10.1016/j.vacuum.2026.115097","url":null,"abstract":"<div><div>Mo<sub>2</sub>TiAlC<sub>2</sub> is a novel MAX phase. Generally, the synthesis of Mo<sub>2</sub>TiAlC<sub>2</sub> require Ti powders as Ti source. In this paper, TiC powders were used as Ti source to synthesize highly pure Mo<sub>2</sub>TiAlC<sub>2</sub>, at 1500 °C for 72 h or at 1600 °C for 3 h. As the Ti source, TiC can directly participate in the formation reaction, significantly improving the reaction kinetics, effectively lowering the synthesis temperature, and enabling the successful preparation of single-phase Mo<sub>2</sub>TiAlC<sub>2</sub> at 1500 °C. Thereafter, the oxidation resistance of Mo<sub>2</sub>TiAlC<sub>2</sub> was characterized. Based on thermal analysis, the oxidation of Mo<sub>2</sub>TiAlC<sub>2</sub> proceeds in three distinct steps: first, partial oxidation of Mo<sub>2</sub>TiAlC<sub>2</sub> initiates at 420 °C, generating MoO<sub>3</sub>, Al<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub>, and TiC; subsequently, between 520 °C and 715 °C, Mo<sub>2</sub>TiAlC<sub>2</sub> and the TiC formed in first step are completely oxidized, yielding MoO<sub>3</sub>, Al<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub>, and TiO<sub>2</sub>; finally, above 870 °C, Al<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub> decomposes and MoO<sub>3</sub> are volatized, resulting in TiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> as the final oxidation products. The unique oxidation intermediates—MoO<sub>3</sub>, Al<sub>2</sub>(MoO<sub>4</sub>)<sub>3</sub>, and TiC—endow Mo<sub>2</sub>TiAlC<sub>2</sub> with significant potential for applications in the field of tribology.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"246 ","pages":"Article 115097"},"PeriodicalIF":3.9,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037681","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 : 2026-01-15DOI: 10.1016/j.vacuum.2026.115095
Zijian Liu , Zijie Li , Zhihao Liu , Yong Wang , Rui Ding , Dezhi Sun , Chao Song , Yongjie Ding
The rapid deployment of commercial mega-constellations has created an urgent demand for electric propulsion systems that combine lightweight design with high power density. Although permanent magnet Hall thrusters have become one of the main practical solutions, they face a critical thermal-magnetic conflict: increasing power density exacerbates heat accumulation, leading to irreversible demagnetization due to the intrinsic thermal sensitivity of the permanent magnets. To address this fundamental challenge, this paper proposes a novel thermal management architecture based on the HEP-1350PM V2 thruster as the platform. The design replaces traditional structures with a lightweight 7075 aluminum alloy frame and integrates a black anodized radiator to form a low-thermal-resistance conduction path, significantly enhancing heat conduction and radiation capabilities. This approach effectively overcomes thermal bottlenecks, enabling stable operation under high thermal loads. Experimental results demonstrate that the thruster can reach thermal equilibrium across a wide power range from 200 W to 2 kW. Its peak total efficiency reaches 63.3 % with xenon propellant and 50.2 % with krypton propellant, while its power-to-weight ratio reaches 1.11 kW/kg, three times that of the SPT-100 thruster.
This study validates the effectiveness of the proposed architecture, providing a thermal management strategy for future high-power, lightweight space propulsion systems.
{"title":"Design and performance of a lightweight, high power density permanent magnet Hall thruster","authors":"Zijian Liu , Zijie Li , Zhihao Liu , Yong Wang , Rui Ding , Dezhi Sun , Chao Song , Yongjie Ding","doi":"10.1016/j.vacuum.2026.115095","DOIUrl":"10.1016/j.vacuum.2026.115095","url":null,"abstract":"<div><div>The rapid deployment of commercial mega-constellations has created an urgent demand for electric propulsion systems that combine lightweight design with high power density. Although permanent magnet Hall thrusters have become one of the main practical solutions, they face a critical thermal-magnetic conflict: increasing power density exacerbates heat accumulation, leading to irreversible demagnetization due to the intrinsic thermal sensitivity of the permanent magnets. To address this fundamental challenge, this paper proposes a novel thermal management architecture based on the HEP-1350PM V2 thruster as the platform. The design replaces traditional structures with a lightweight 7075 aluminum alloy frame and integrates a black anodized radiator to form a low-thermal-resistance conduction path, significantly enhancing heat conduction and radiation capabilities. This approach effectively overcomes thermal bottlenecks, enabling stable operation under high thermal loads. Experimental results demonstrate that the thruster can reach thermal equilibrium across a wide power range from 200 W to 2 kW. Its peak total efficiency reaches 63.3 % with xenon propellant and 50.2 % with krypton propellant, while its power-to-weight ratio reaches 1.11 kW/kg, three times that of the SPT-100 thruster.</div><div>This study validates the effectiveness of the proposed architecture, providing a thermal management strategy for future high-power, lightweight space propulsion systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115095"},"PeriodicalIF":3.9,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026011","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 : 2026-01-14DOI: 10.1016/j.vacuum.2026.115088
Ziyan Dai , Saifei Wang , Xueli Xiang , Yan Chen , Shanjun Chen , Weibin Zhang
The structural, mechanical, hydrogen storage, optical, electronic, dynamic, and thermodynamic characteristics of XSc3H8 (X = Rb and Cs) compounds are investigated via first-principles calculations. The negative formation energies of RbSc3H8 (−0.55 eV/atom) and CsSc3H8 (−0.46 eV/atom) confirm their thermodynamic stability. The absence of imaginary frequencies in the phonon spectra verifies the dynamic stability of both compounds. The mechanical stability of RbSc3H8 and CsSc3H8 is validated by the elastic constants that meet the Born stability criteria. RbSc3H8 and CsSc3H8 exhibit gravimetric hydrogen storage capacities of 3.53 wt% and 2.92 wt%, respectively. The hydrogen desorption temperatures are 402.80 K for RbSc3H8 and 339.01 K for CsSc3H8, which are suitable for H2 desorption. The mechanical properties indicate that RbSc3H8 exhibits brittle characteristics, whereas CsSc3H8 displays ductility, and both materials exhibit anisotropic characteristics. The analysis of electronic band structures reveals that these hydrides display metallic properties. Their optical characteristics indicate that they are materials with high polarizability. Our research suggests that RbSc3H8 exhibits greater potential as a hydrogen storage material due to its superior gravimetric hydrogen storage capacity, making it particularly suitable for weight-sensitive applications such as mobile hydrogen storage. While CsSc3H8 offers advantages in low-temperature applications owing to its lower desorption temperature.
{"title":"First-principles study of efficient solid-state hydrogen storage materials XSc3H8 (X = Rb and Cs)","authors":"Ziyan Dai , Saifei Wang , Xueli Xiang , Yan Chen , Shanjun Chen , Weibin Zhang","doi":"10.1016/j.vacuum.2026.115088","DOIUrl":"10.1016/j.vacuum.2026.115088","url":null,"abstract":"<div><div>The structural, mechanical, hydrogen storage, optical, electronic, dynamic, and thermodynamic characteristics of XSc<sub>3</sub>H<sub>8</sub> (X = Rb and Cs) compounds are investigated via first-principles calculations. The negative formation energies of RbSc<sub>3</sub>H<sub>8</sub> (−0.55 eV/atom) and CsSc<sub>3</sub>H<sub>8</sub> (−0.46 eV/atom) confirm their thermodynamic stability. The absence of imaginary frequencies in the phonon spectra verifies the dynamic stability of both compounds. The mechanical stability of RbSc<sub>3</sub>H<sub>8</sub> and CsSc<sub>3</sub>H<sub>8</sub> is validated by the elastic constants that meet the Born stability criteria. RbSc<sub>3</sub>H<sub>8</sub> and CsSc<sub>3</sub>H<sub>8</sub> exhibit gravimetric hydrogen storage capacities of 3.53 wt% and 2.92 wt%, respectively. The hydrogen desorption temperatures are 402.80 K for RbSc<sub>3</sub>H<sub>8</sub> and 339.01 K for CsSc<sub>3</sub>H<sub>8</sub>, which are suitable for H<sub>2</sub> desorption. The mechanical properties indicate that RbSc<sub>3</sub>H<sub>8</sub> exhibits brittle characteristics, whereas CsSc<sub>3</sub>H<sub>8</sub> displays ductility, and both materials exhibit anisotropic characteristics. The analysis of electronic band structures reveals that these hydrides display metallic properties. Their optical characteristics indicate that they are materials with high polarizability. Our research suggests that RbSc<sub>3</sub>H<sub>8</sub> exhibits greater potential as a hydrogen storage material due to its superior gravimetric hydrogen storage capacity, making it particularly suitable for weight-sensitive applications such as mobile hydrogen storage. While CsSc<sub>3</sub>H<sub>8</sub> offers advantages in low-temperature applications owing to its lower desorption temperature.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"246 ","pages":"Article 115088"},"PeriodicalIF":3.9,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145977728","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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