Pub Date : 2026-01-29DOI: 10.1016/j.vacuum.2026.115144
Xinru Lin, Zheming Feng, Peng Song
One-dimensional (1D) MoO3 nanobelts and MoO3 nanobelts/Ti3C2Tx MXene composites were successfully fabricated using hydrothermal and electrostatic self-assembly technology. Characterization indicates that the composites have more unique microstructure and a higher surface adsorbed oxygen content. The gas sensitivity performance results indicate that the optimal operating temperature (180 °C) of MoO3 nanobelts/Ti3C2Tx MXene composites gas sensor is significantly reduced, and the response value to 50 ppm MEA rose from 298.3 % to 470.1 %. The response/recovery times are only 5 s and 9 s respectively, and it has stability and good selectivity for MEA gas. In addition, this study elaborated on its sensing mechanism in depth by constructing a mechanism model. This study proposes a technical solution to enhancing the gas-sensitive performance of MoO3 through efficient compounding with other functional materials, and also lays a foundation for the research and development and practical application of high-performance MEA gas sensors.
{"title":"Synthesis of 1D/2D MoO3 nanobelts/Ti3C2Tx MXene composites for selective detection of ethanolamine","authors":"Xinru Lin, Zheming Feng, Peng Song","doi":"10.1016/j.vacuum.2026.115144","DOIUrl":"10.1016/j.vacuum.2026.115144","url":null,"abstract":"<div><div>One-dimensional (1D) MoO<sub>3</sub> nanobelts and MoO<sub>3</sub> nanobelts/Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene composites were successfully fabricated using hydrothermal and electrostatic self-assembly technology. Characterization indicates that the composites have more unique microstructure and a higher surface adsorbed oxygen content. The gas sensitivity performance results indicate that the optimal operating temperature (180 °C) of MoO<sub>3</sub> nanobelts/Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene composites gas sensor is significantly reduced, and the response value to 50 ppm MEA rose from 298.3 % to 470.1 %. The response/recovery times are only 5 s and 9 s respectively, and it has stability and good selectivity for MEA gas. In addition, this study elaborated on its sensing mechanism in depth by constructing a mechanism model. This study proposes a technical solution to enhancing the gas-sensitive performance of MoO<sub>3</sub> through efficient compounding with other functional materials, and also lays a foundation for the research and development and practical application of high-performance MEA gas sensors.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115144"},"PeriodicalIF":3.9,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080211","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 reveals the synergistic degradation mechanism between surface oxide layer and interface diffusion barrier in CrSi (7.7 at.% Si) coatings during 1–8 h oxidation in 1200 °C steam. Initially (0–1 h), a dense Cr2O3/SiO2 duplex layer develops on the surface, while a stoichiometric Zr2Si diffusion barrier develops at the interface, providing optimal protection. During 2–6 h, Si depletion causes the transformation of subsurface SiO2 from continuous to discrete particles and triggers Zr-rich phase precipitation within the Zr2Si layer, leading to progressive performance degradation. At the failure stage (7–8 h), following the breakdown of the Zr2Si diffusion barrier, ZrO2 networks form and serve as short-circuit paths, which significantly accelerate oxygen transport to the substrate.
{"title":"Oxidation behavior and synergistic surface-interface degradation mechanism of CrSi coatings in 1200 °C steam","authors":"Song Zeng, Chang Jiang, Youxing He, Yiyou Wu, Xuebing Yang, Jiuming Yu, Linwei Zhang, Wenfu Chen","doi":"10.1016/j.vacuum.2026.115143","DOIUrl":"10.1016/j.vacuum.2026.115143","url":null,"abstract":"<div><div>This study reveals the synergistic degradation mechanism between surface oxide layer and interface diffusion barrier in CrSi (7.7 at.% Si) coatings during 1–8 h oxidation in 1200 °C steam. Initially (0–1 h), a dense Cr<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> duplex layer develops on the surface, while a stoichiometric Zr<sub>2</sub>Si diffusion barrier develops at the interface, providing optimal protection. During 2–6 h, Si depletion causes the transformation of subsurface SiO<sub>2</sub> from continuous to discrete particles and triggers Zr-rich phase precipitation within the Zr<sub>2</sub>Si layer, leading to progressive performance degradation. At the failure stage (7–8 h), following the breakdown of the Zr<sub>2</sub>Si diffusion barrier, ZrO<sub>2</sub> networks form and serve as short-circuit paths, which significantly accelerate oxygen transport to the substrate.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115143"},"PeriodicalIF":3.9,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080217","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 : 2026-01-28DOI: 10.1016/j.vacuum.2026.115135
Jinyin Fu , Libo Zhou , Zhou Li , Cong Li , Minbo Wang , Jian Chen
In this study, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) alloy was fabricated using laser powder bed fusion. By analyzing the printing quality and mechanical properties of TC11 alloy printed under different process parameters, an optimum processing window (laser power of 200 W, laser scanning speed of 1100 mm/s) was identified. Under the optimal process parameters, the sample achieved a relative density of 99.6 % and excellent mechanical properties (Ultimate Tensile Strength of 1331 ± 11 MPa, Yield Strength of 1004 ± 13 MPa and Elongation of 12.1 ± 1.2 %). After heat-treated at 900 °C, the sample exhibited an equiaxed α phase and thin film β phase with the elongation increasing by approximately 39.3 % (from 12.1 ± 1.2 % to 16.8 ± 0.6 %), while the yield strength (996 ± 1 MPa) remained at the as-built level. The enhanced ductility of the heat-treated sample is attributed to three key factors: the decreased low-angle grain boundaries which minimizes stress concentration during deformation, the reduced α′ martensite with thin-film β-phase formation (coordinating plastic flow via a ductile phase), and the improved α-β crystallographic coincidence with reduced lattice distortion, lowering interfacial stress and promoting slip transmission.
{"title":"Microstructure and mechanical properties of titanium alloy via laser powder bed fusion and heat treatment","authors":"Jinyin Fu , Libo Zhou , Zhou Li , Cong Li , Minbo Wang , Jian Chen","doi":"10.1016/j.vacuum.2026.115135","DOIUrl":"10.1016/j.vacuum.2026.115135","url":null,"abstract":"<div><div>In this study, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) alloy was fabricated using laser powder bed fusion. By analyzing the printing quality and mechanical properties of TC11 alloy printed under different process parameters, an optimum processing window (laser power of 200 W, laser scanning speed of 1100 mm/s) was identified. Under the optimal process parameters, the sample achieved a relative density of 99.6 % and excellent mechanical properties (Ultimate Tensile Strength of 1331 ± 11 MPa, Yield Strength of 1004 ± 13 MPa and Elongation of 12.1 ± 1.2 %). After heat-treated at 900 °C, the sample exhibited an equiaxed α phase and thin film β phase with the elongation increasing by approximately 39.3 % (from 12.1 ± 1.2 % to 16.8 ± 0.6 %), while the yield strength (996 ± 1 MPa) remained at the as-built level. The enhanced ductility of the heat-treated sample is attributed to three key factors: the decreased low-angle grain boundaries which minimizes stress concentration during deformation, the reduced α′ martensite with thin-film β-phase formation (coordinating plastic flow via a ductile phase), and the improved α-β crystallographic coincidence with reduced lattice distortion, lowering interfacial stress and promoting slip transmission.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115135"},"PeriodicalIF":3.9,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080122","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 : 2026-01-27DOI: 10.1016/j.vacuum.2026.115142
Angel Regalado-Contreras , Jonathan Rosas-Alcántara , Karla Paola Valdez-Núñez , Mayra Cecilia Ramírez-Camacho , Wencel de la Cruz
p-type TiOx thin films have been fabricated using vacuum-based techniques at different deposition pressures, but no reproducible processing window has been established. Herein, TiOx thin films were deposited by laser ablation of a Ti target under O2 atmospheres at pressures ranging from 1.2 × 10−5 to 0.1 Torr. In vacuo X-ray Photoelectron Spectroscopy (XPS) revealed Ti4+/Ti3+ mixed valence below 10−2 Torr and exclusively Ti4+ above this threshold. Quantification based on Gaussian peak deconvolution revealed Ti4+ ranging from 20 to 30.6 at.%, Ti3+ from 10.1 to 1.5 at.%, and oxygen approximately constant at ∼69 at.%, with an uncertainty of ±5 %. The electrical properties were carrier concentrations from 2 × 1020 cm−3 (electrons) to 2 × 1016 cm−3 (holes), resistivity from 0.4 to 460 Ω cm, and mobility from 0.5 to 6 cm2 V−1 s−1. The films with mixed Ti valence were n-type and those with Ti4+ alone were p-type. Cathodoluminescence, in combination with XPS, revealed shallow acceptor levels mediating p-type conductivity, located at 0.32–0.36 eV above the VBM. Optically, average transmittance as high as 66 % on the visible spectrum (350–750 nm) was achieved. Surface morphology analyzed through atomic force microscopy revealed RMS roughness as low as 0.77 nm. Thin-Film-Transistors (TFT) were fabricated by photolithography. The output/transfer characteristics evolve from non-saturated/weak gate modulation to fully saturated/gate-controlled, consistent with TiOx channels exhibiting carrier concentrations on the order of 1019 to 1017 cm−3, respectively. This study advances the body of knowledge on semiconducting TiOx thin films and their reproducible integration into TFT with tunable performance.
{"title":"Carrier tuning in room temperature laser-ablated TiOx thin films: In vacuo X-ray photoelectron spectroscopy insights","authors":"Angel Regalado-Contreras , Jonathan Rosas-Alcántara , Karla Paola Valdez-Núñez , Mayra Cecilia Ramírez-Camacho , Wencel de la Cruz","doi":"10.1016/j.vacuum.2026.115142","DOIUrl":"10.1016/j.vacuum.2026.115142","url":null,"abstract":"<div><div>p-type TiO<sub>x</sub> thin films have been fabricated using vacuum-based techniques at different deposition pressures, but no reproducible processing window has been established. Herein, TiO<sub>x</sub> thin films were deposited by laser ablation of a Ti target under O<sub>2</sub> atmospheres at pressures ranging from 1.2 × 10<sup>−5</sup> to 0.1 Torr. <em>In vacuo</em> X-ray Photoelectron Spectroscopy (XPS) revealed Ti<sup>4+</sup>/Ti<sup>3+</sup> mixed valence below 10<sup>−2</sup> Torr and exclusively Ti<sup>4+</sup> above this threshold. Quantification based on Gaussian peak deconvolution revealed Ti<sup>4+</sup> ranging from 20 to 30.6 at.%, Ti<sup>3+</sup> from 10.1 to 1.5 at.%, and oxygen approximately constant at ∼69 at.%, with an uncertainty of ±5 %. The electrical properties were carrier concentrations from 2 × 10<sup>20</sup> cm<sup>−3</sup> (electrons) to 2 × 10<sup>16</sup> cm<sup>−3</sup> (holes), resistivity from 0.4 to 460 Ω cm, and mobility from 0.5 to 6 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>. The films with mixed Ti valence were n-type and those with Ti<sup>4+</sup> alone were p-type. Cathodoluminescence, in combination with XPS, revealed shallow acceptor levels mediating p-type conductivity, located at 0.32–0.36 eV above the VBM. Optically, average transmittance as high as 66 % on the visible spectrum (350–750 nm) was achieved. Surface morphology analyzed through atomic force microscopy revealed RMS roughness as low as 0.77 nm. Thin-Film-Transistors (TFT) were fabricated by photolithography. The output/transfer characteristics evolve from non-saturated/weak gate modulation to fully saturated/gate-controlled, consistent with TiO<sub>x</sub> channels exhibiting carrier concentrations on the order of 10<sup>19</sup> to 10<sup>17</sup> cm<sup>−3</sup>, respectively. This study advances the body of knowledge on semiconducting TiO<sub>x</sub> thin films and their reproducible integration into TFT with tunable performance.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115142"},"PeriodicalIF":3.9,"publicationDate":"2026-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080214","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 presents a water vapor-assisted solid-state sintering strategy to fabricate CsPbI3@SiO2 perovskite composites. Through high humidity and temperature, CsPbI3 nanocrystals are efficiently encapsulated within a SiO2 matrix, resulting in dramatically enhanced stability. The composite retains over 85 % of its initial luminescence after 360 days in ambient conditions and demonstrates excellent resistance to polar solvents and acids. Due to its high stability, the composite exhibits promising performance in white light-emitting diodes (WLEDs) and information encryption applications, providing a viable pathway toward practical perovskite-based devices.
{"title":"Vapor-assisted solid-state sintering of CsPbI3@SiO2 core-shell nanocrystals for enhanced environmental stability","authors":"Longxun Teng, Xin Li, Yuanxin Chunyu, Jiaxiang Liang, Xinyue Shao, Haiqing Sun, Xiaoyuan Zhan, Weiwei Zhang, Rui Liu, Jianxu Ding, Huiling Zhu","doi":"10.1016/j.vacuum.2026.115139","DOIUrl":"10.1016/j.vacuum.2026.115139","url":null,"abstract":"<div><div>This study presents a water vapor-assisted solid-state sintering strategy to fabricate CsPbI<sub>3</sub>@SiO<sub>2</sub> perovskite composites. Through high humidity and temperature, CsPbI<sub>3</sub> nanocrystals are efficiently encapsulated within a SiO<sub>2</sub> matrix, resulting in dramatically enhanced stability. The composite retains over 85 % of its initial luminescence after 360 days in ambient conditions and demonstrates excellent resistance to polar solvents and acids. Due to its high stability, the composite exhibits promising performance in white light-emitting diodes (WLEDs) and information encryption applications, providing a viable pathway toward practical perovskite-based devices.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115139"},"PeriodicalIF":3.9,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080119","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 : 2026-01-23DOI: 10.1016/j.vacuum.2026.115128
Xiaokang Yang , Hongze Fang , Lingyan Zhou , Xianfei Ding , Fuxin Wang , Bobo Li , Baohui Zhu , Ruirun Chen
The influence of temperature gradient on the microstructure and high-temperature mechanical behavior of directionally solidified Ti-47Al-6Nb-0.1C-1.6Ta-0.8Hf alloys was systematically investigated. Columnar grain alignment and lamellar orientation improve with increasing power up to 45 kW, beyond which orientation dispersion and equiaxed grains emerge, driven by the stability of the solidification front and competitive β-dendrite growth. High temperature gradients enhance peritectic reaction kinetics, promoting α-variant selection, lamellar convergence, and suppression of residual β, whereas low gradients lead to dispersed lamellar structures. Elemental analysis reveals uniform hydrogen and oxygen distribution with minimal segregation, attributed to high-vacuum melting and rapid peritectic consumption of β. High-temperature tensile testing at 900 °C shows peak strength and ductility at 45 kW, correlated with effective dislocation blockage at B2/γ and γ/α2 interfaces, where high slip-energy barriers and controlled dislocation transmission mitigate local stress concentrations. These findings demonstrate that precise control of heating power and temperature gradient enables the optimization of microstructure, phase transformation, and high-temperature mechanical performance in TiAl alloys.
{"title":"Tailoring peritectic solidification and lamellar orientation in TiAl alloys through controlled heating power","authors":"Xiaokang Yang , Hongze Fang , Lingyan Zhou , Xianfei Ding , Fuxin Wang , Bobo Li , Baohui Zhu , Ruirun Chen","doi":"10.1016/j.vacuum.2026.115128","DOIUrl":"10.1016/j.vacuum.2026.115128","url":null,"abstract":"<div><div>The influence of temperature gradient on the microstructure and high-temperature mechanical behavior of directionally solidified Ti-47Al-6Nb-0.1C-1.6Ta-0.8Hf alloys was systematically investigated. Columnar grain alignment and lamellar orientation improve with increasing power up to 45 kW, beyond which orientation dispersion and equiaxed grains emerge, driven by the stability of the solidification front and competitive β-dendrite growth. High temperature gradients enhance peritectic reaction kinetics, promoting α-variant selection, lamellar convergence, and suppression of residual β, whereas low gradients lead to dispersed lamellar structures. Elemental analysis reveals uniform hydrogen and oxygen distribution with minimal segregation, attributed to high-vacuum melting and rapid peritectic consumption of β. High-temperature tensile testing at 900 °C shows peak strength and ductility at 45 kW, correlated with effective dislocation blockage at B2/γ and γ/α2 interfaces, where high slip-energy barriers and controlled dislocation transmission mitigate local stress concentrations. These findings demonstrate that precise control of heating power and temperature gradient enables the optimization of microstructure, phase transformation, and high-temperature mechanical performance in TiAl alloys.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115128"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080118","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 : 2026-01-23DOI: 10.1016/j.vacuum.2026.115133
Marcell Gajdics , Ildikó Cora , Tamás Kolonits , György Sáfrán , Edit Szilágyi , Zsolt Zolnai , Béla Pécz
Gallium oxynitride thin films were deposited by reactive RF sputtering from a liquid Ga target in a working gas mixture of argon, oxygen and nitrogen, with changing oxygen proportion. A combinatorial deposition method was applied that resulted in Ga-O-N samples of varying composition and enabled the characterization of material properties with high throughput over a wide composition range. The optical properties of the films were determined by spectroscopic ellipsometry, while X-ray diffraction and transmission electron microscopy were applied for structural characterization. The composition (measured by energy dispersive spectroscopy and elastic recoil detection analysis), structure and morphology of the films depended on the deposition conditions, especially the actual oxygen flow rate. The dependence of the refractive index and the optical gap on the elemental composition was determined and their values were plotted in ternary Ga-O-N composition diagrams. The same optical properties can occur for different compositions. It was shown that by varying the composition, the optical properties of gallium oxynitride films can be tuned.
{"title":"Composition-dependent structural and optical properties of combinatorially deposited, RF sputtered gallium oxynitride layers","authors":"Marcell Gajdics , Ildikó Cora , Tamás Kolonits , György Sáfrán , Edit Szilágyi , Zsolt Zolnai , Béla Pécz","doi":"10.1016/j.vacuum.2026.115133","DOIUrl":"10.1016/j.vacuum.2026.115133","url":null,"abstract":"<div><div>Gallium oxynitride thin films were deposited by reactive RF sputtering from a liquid Ga target in a working gas mixture of argon, oxygen and nitrogen, with changing oxygen proportion. A combinatorial deposition method was applied that resulted in Ga-O-N samples of varying composition and enabled the characterization of material properties with high throughput over a wide composition range. The optical properties of the films were determined by spectroscopic ellipsometry, while X-ray diffraction and transmission electron microscopy were applied for structural characterization. The composition (measured by energy dispersive spectroscopy and elastic recoil detection analysis), structure and morphology of the films depended on the deposition conditions, especially the actual oxygen flow rate. The dependence of the refractive index and the optical gap on the elemental composition was determined and their values were plotted in ternary Ga-O-N composition diagrams. The same optical properties can occur for different compositions. It was shown that by varying the composition, the optical properties of gallium oxynitride films can be tuned.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115133"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080114","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 : 2026-01-23DOI: 10.1016/j.vacuum.2026.115134
Mikhail Popov , Pavel Pivovarov , Fedor Khorobrykh , Dmitry Sovyk , Victor Ralchenko
A comparative study of the wettability of ultrahard amorphous carbon (UAC), formed by sp3 bonds alone, and diamond (100) facets, has been performed experimentally using atomic force spectroscopy. The capillary forces for UAC and diamond are found to be similar within the 10 % measurement error. Based on a relationship between the capillary force and the contact angle for the substrates, it is concluded that the contact angles for hydrogenated diamond (81°) and ultrahard amorphous sp3 carbon are close.
{"title":"Similar wettability of ultrahard sp3-bonded amorphous carbon and diamond (100) revealed by atomic force spectroscopy","authors":"Mikhail Popov , Pavel Pivovarov , Fedor Khorobrykh , Dmitry Sovyk , Victor Ralchenko","doi":"10.1016/j.vacuum.2026.115134","DOIUrl":"10.1016/j.vacuum.2026.115134","url":null,"abstract":"<div><div>A comparative study of the wettability of ultrahard amorphous carbon (UAC), formed by sp<sup>3</sup> bonds alone, and diamond (100) facets, has been performed experimentally using atomic force spectroscopy. The capillary forces for UAC and diamond are found to be similar within the 10 % measurement error. Based on a relationship between the capillary force and the contact angle for the substrates, it is concluded that the contact angles for hydrogenated diamond (81°) and ultrahard amorphous sp<sup>3</sup> carbon are close.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115134"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080213","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 : 2026-01-23DOI: 10.1016/j.vacuum.2026.115131
Chao-Wei Huang , Sheng-Wen Liu , Wai-Cheng Lien , Yueh-Heng Li
This study presents the development and extended operational testing of a Coaxial Pulsed Plasma Thruster (CPPT) specifically designed for small satellite propulsion applications. The annular ignition system demonstrated highly stable performance over 38,000 firing cycles, while the thruster itself underwent over 100,000 discharge cycles at a capacitor discharge energy of 18.4 J, achieving a maximum thrust efficiency of 37 %. Fast Faraday Cup diagnostics revealed that the plasma plume was primarily confined between −30° and 0°, and high-speed imaging confirmed that the plume direction varied with ignition location. Thrust measurements using a hanging pendulum thrust stand indicated impulse bits of 181 μN s or 134 μN s, depending on the discharge waveform characteristics. Experimental analysis showed that using 304 stainless steel as both the cathode and ignition electrode material enabled reliable ignition under vacuum conditions. Although visible metallic powder deposition was observed on the surface of the polytetrafluoroethylene (PTFE) propellant, it did not significantly degrade thruster performance, as evidenced by sustained arc discharge stability and minimal electrode erosion. Overall, the CPPT exhibited low ablation rates and high operational efficiency, highlighting its strong potential as a long-lifetime, low-power propulsion system for microsatellites and other space missions.
{"title":"Electrode material selection and plasma-surface interactions in a coaxial pulsed plasma thruster","authors":"Chao-Wei Huang , Sheng-Wen Liu , Wai-Cheng Lien , Yueh-Heng Li","doi":"10.1016/j.vacuum.2026.115131","DOIUrl":"10.1016/j.vacuum.2026.115131","url":null,"abstract":"<div><div>This study presents the development and extended operational testing of a Coaxial Pulsed Plasma Thruster (CPPT) specifically designed for small satellite propulsion applications. The annular ignition system demonstrated highly stable performance over 38,000 firing cycles, while the thruster itself underwent over 100,000 discharge cycles at a capacitor discharge energy of 18.4 J, achieving a maximum thrust efficiency of 37 %. Fast Faraday Cup diagnostics revealed that the plasma plume was primarily confined between −30° and 0°, and high-speed imaging confirmed that the plume direction varied with ignition location. Thrust measurements using a hanging pendulum thrust stand indicated impulse bits of 181 μN s or 134 μN s, depending on the discharge waveform characteristics. Experimental analysis showed that using 304 stainless steel as both the cathode and ignition electrode material enabled reliable ignition under vacuum conditions. Although visible metallic powder deposition was observed on the surface of the polytetrafluoroethylene (PTFE) propellant, it did not significantly degrade thruster performance, as evidenced by sustained arc discharge stability and minimal electrode erosion. Overall, the CPPT exhibited low ablation rates and high operational efficiency, highlighting its strong potential as a long-lifetime, low-power propulsion system for microsatellites and other space missions.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115131"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080115","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}
High Entropy alloys (HEAs) have recently emerged as promising candidates for thermoelectric applications due to their tunable transport properties enabled by entropy engineering. In this work, we investigate the effect of entropy engineering on the thermal and electrical transport properties of CoCrFeNi system through Ag alloying. The CoCrFeNiAg0.2 alloy exhibited a low lattice thermal conductivity of ∼1.34 Wm−1K−1 at 700 K, which is ∼8.6 times lower than that of the parent alloy, attributed to severe lattice distortions induced by mass and size disorder. All the HEA compositions displayed rare p-type conduction. Notably, the CoCrFeNiAg0.1 showed the highest Seebeck coefficient of ∼17.5 μVK−1, representing a 44.6 % enhancement over the reference alloy, along with the highest power factor of 213 μWm−1K−2 at 700 K. These results demonstrate that entropy-driven atomic disorder is an effective strategy to suppress phonon transport and enhance the thermoelectric performance in metallic HEAs.
{"title":"Entropy engineered p-type Ag-alloyed CoCrFeNi metallic high entropy alloys with low lattice thermal conductivity","authors":"K. Arun , Kowsalya Senthil Kumar , Navaneethan Mani , Senthil Kumar Eswaran","doi":"10.1016/j.vacuum.2026.115130","DOIUrl":"10.1016/j.vacuum.2026.115130","url":null,"abstract":"<div><div>High Entropy alloys (HEAs) have recently emerged as promising candidates for thermoelectric applications due to their tunable transport properties enabled by entropy engineering. In this work, we investigate the effect of entropy engineering on the thermal and electrical transport properties of CoCrFeNi system through Ag alloying. The CoCrFeNiAg<sub>0.2</sub> alloy exhibited a low lattice thermal conductivity of ∼1.34 Wm<sup>−1</sup>K<sup>−1</sup> at 700 K, which is ∼8.6 times lower than that of the parent alloy, attributed to severe lattice distortions induced by mass and size disorder. All the HEA compositions displayed rare <em>p</em>-type conduction. Notably, the CoCrFeNiAg<sub>0.1</sub> showed the highest Seebeck coefficient of ∼17.5 μVK<sup>−1</sup>, representing a 44.6 % enhancement over the reference alloy, along with the highest power factor of 213 μWm<sup>−1</sup>K<sup>−2</sup> at 700 K. These results demonstrate that entropy-driven atomic disorder is an effective strategy to suppress phonon transport and enhance the thermoelectric performance in metallic HEAs.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115130"},"PeriodicalIF":3.9,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080123","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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