IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-19 DOI: 10.1016/j.vacuum.2025.114428

Takahiro Gotow , Tsutomu Sonoda , Tokio Takahashi , Hisashi Yamada , Toshihide Ide , Reiko Azumi , Mitsuaki Shimizu , Yosuke Tsunooka , Shota Seki , Kentaro Kutsukake , Toru Ujihara

引用次数: 0

A low-conductance gas neutralizer cell for an ion accelerator: Modeling and development using the angular coefficient method in the free molecular flow regime 离子加速器用低电导气体中和电池：在自由分子流动条件下用角系数法建模和开发

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-17 DOI: 10.1016/j.vacuum.2025.114421

Amin Masoumzadeh , Morteza Habibi , Hamid Reza Mirzaei

{"title":"A low-conductance gas neutralizer cell for an ion accelerator: Modeling and development using the angular coefficient method in the free molecular flow regime","authors":"Amin Masoumzadeh , Morteza Habibi , Hamid Reza Mirzaei","doi":"10.1016/j.vacuum.2025.114421","DOIUrl":"10.1016/j.vacuum.2025.114421","url":null,"abstract":"<div><div>A gas neutralizer cell is a charge exchange cell where ion beam particles exchange charge with gas molecules, resulting in neutralization. This study employed a numerical fluid model using the angular coefficient method within a free molecular flow regime to develop a low-conductance neutralizer cell. The model was also applied to an ion accelerator equipped with the cell, computing gas pressure in both the cell and the accelerator. The gas pressure inside the cell directly influences the ion neutralization. To achieve optimal pressure, which must exceed beamline pressure, a low-conductance geometry is necessary to reduce gas conductance. Dividing the cell transversely into several longitudinal parallel channels was found to decrease gas conductance and increase gas pressure within the cell. However, a multi-channel configuration raised beam loss due to the interaction of divergent beamlets with channel walls, necessitating a study of geometric efficiency. The results and evaluations indicated that the proposed 9-column, 3-row configuration achieves the required pressure for neutralization while minimizing beam loss and ensuring construction feasibility. The total efficiency of this neutralizer cell surpasses that of a one-channel design for beam divergences below 30 mrad. The constructed cell was tested, and it validated the fluid model.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114421"},"PeriodicalIF":3.8,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144114835","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}

引用次数: 0

Deposition of aluminium oxide coatings by a system based on gridless ion acceleration 基于无栅离子加速系统的氧化铝涂层沉积

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-16 DOI: 10.1016/j.vacuum.2025.114419

I.V. Lopatin, Yu.H. Akhmadeev, N.N. Koval, E.A. Petrikova

引用次数: 0

First-principles prediction of the physical properties of the Al-based hydride XAlH5 (X = Ca, Sr, Ba) for hydrogen storage applications 储氢用铝基氢化物XAlH5 （X = Ca, Sr, Ba）物理性质的第一性原理预测

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-16 DOI: 10.1016/j.vacuum.2025.114422

Lixian Yang , Yong Cao , Linjie Miao , Nan Qu

{"title":"First-principles prediction of the physical properties of the Al-based hydride XAlH5 (X = Ca, Sr, Ba) for hydrogen storage applications","authors":"Lixian Yang , Yong Cao , Linjie Miao , Nan Qu","doi":"10.1016/j.vacuum.2025.114422","DOIUrl":"10.1016/j.vacuum.2025.114422","url":null,"abstract":"<div><div>To identify potential hydrogen storage materials, this study uses first-principles calculations to predict the thermodynamic, storage, mechanical, electronic, optical, and dynamic properties of aluminum-based hydride XAlH<sub>5</sub> (X = Ca, Sr, Ba). The negative formation enthalpy of XAlH<sub>5</sub> (X = Ca, Sr, Ba) hydrides, along with Born stability criteria and phonon dispersion analysis, indicates their thermodynamic, mechanical, and dynamic stability. Predictions for the B/G ratio and Poisson's ratio reveal that CaAlH<sub>5</sub> is ductile, whereas SrAlH<sub>5</sub> and BaAlH<sub>5</sub> are brittle materials. Electronic property predictions show that aluminum-based hydride XAlH<sub>5</sub> (X = Ca, Sr, Ba) are semiconductors. Bonding analysis reveals that CaAlH<sub>5</sub> contains only ionic bonds, while SrAlH<sub>5</sub> and BaAlH<sub>5</sub> include both covalent and ionic bonds. CaAlH<sub>5</sub>, with the smallest band gap, facilitates electron transitions between the valence and conduction bands, making it ideal for hydrogen release. The predicted weight hydrogen storage capacities for XAlH<sub>5</sub> (X = Ca, Sr, Ba) hydrides are 6.99 wt% for CaAlH<sub>5</sub>, 4.21 wt% for SrAlH<sub>5</sub>, and 2.98 wt% for BaAlH<sub>5</sub>, with hydrogen desorption temperatures of 277K, 297K, and 333K. Among the XAlH<sub>5</sub> (X = Ca, Sr, Ba) hydrides, CaAlH<sub>5</sub> demonstrates the best hydrogen storage potential and should be considered a promising material for future hydrogen storage applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114422"},"PeriodicalIF":3.8,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107246","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}

引用次数: 0

SGOI wafers with high structural and electrical quality fabricated through Ge condensation in SiGe/SOI 在SiGe/SOI中通过Ge缩合制备出具有高结构质量和高电学质量的SGOI晶圆

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-16 DOI: 10.1016/j.vacuum.2025.114410

Mansour Aouassa , Arette-Hourqet Adam , Ismail Madaci , Mathieu Abel , Anne-Flore Mallet , Olivier Gourhant , Isabelle Berbezier , A.K. Aladim

{"title":"SGOI wafers with high structural and electrical quality fabricated through Ge condensation in SiGe/SOI","authors":"Mansour Aouassa , Arette-Hourqet Adam , Ismail Madaci , Mathieu Abel , Anne-Flore Mallet , Olivier Gourhant , Isabelle Berbezier , A.K. Aladim","doi":"10.1016/j.vacuum.2025.114410","DOIUrl":"10.1016/j.vacuum.2025.114410","url":null,"abstract":"<div><div>This work presents the structural and electrical performance of novel SiGe-on-Insulator (SGOI) wafers fabricated using a new thermal condensation process for germanium (Ge) in SiGe, leveraging advanced vacuum technology to ensure precise control and high purity. In this process, a 15 nm thick Si<sub>0.82</sub>Ge<sub>0.18</sub> film is first epitaxially grown on an ultrathin 8 nm silicon-on-insulator (SOI) wafer via LPCVD. A subsequent low-temperature thermal oxidation at 750 °C converts the Si<sub>0.82</sub>Ge<sub>0.18</sub>/SOI film into a high-Ge-content (47 %) SGOI wafer with a defect-free structure and an exceptionally smooth surface. Electrical characterization through current-voltage (I-V), capacitance-voltage (C-V), and impedance measurements demonstrates the exceptional properties of the resulting SGOI wafer, including low leakage current, low interface state density, and high electrical stability. These results showcase the effectiveness of the novel Ge condensation process in producing low-cost, high-performance SGOI wafers for advanced optoelectronic and photonic applications.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114410"},"PeriodicalIF":3.8,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089650","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}

引用次数: 0

Effect of temperature on the nanoindentation behavior of single crystal GaN by molecular dynamics simulations 温度对单晶GaN纳米压痕行为的影响

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-16 DOI: 10.1016/j.vacuum.2025.114423

Zhijie Zhang , Zhenqiao Zhang , Yingying Wang , Zerui Zhao , Zhonghan Yu , Wenjuan Xing , Dan Zhao , Yihan Niu , Bo Zhu , Hongwei Zhao

{"title":"Effect of temperature on the nanoindentation behavior of single crystal GaN by molecular dynamics simulations","authors":"Zhijie Zhang , Zhenqiao Zhang , Yingying Wang , Zerui Zhao , Zhonghan Yu , Wenjuan Xing , Dan Zhao , Yihan Niu , Bo Zhu , Hongwei Zhao","doi":"10.1016/j.vacuum.2025.114423","DOIUrl":"10.1016/j.vacuum.2025.114423","url":null,"abstract":"<div><div>Comprehending the nano-deformation mechanisms of GaN under the joint influence of temperature and loads is significant for the production and reliability service of high-quality GaN-based devices. Nanoindentation molecular dynamics simulations are conducted on the c-plane of wurtzite GaN single crystal samples within the temperature range of 10K–1200K. The results indicate that the mechanical properties of GaN exhibit favorable temperature stability. The pop-in events observed in GaN nanoindentation are caused by dislocation nucleation beneath the surface. The dynamics of dislocation motion during the GaN nanoindentation process are explained. An analysis of the interactions between dislocations revealed dislocation entanglement and atomic compression in GaN during multi-point loading. Two phase transformations are recognized in GaN: the wurtzite structure changes to the h-MgO structure in the elastic deformation and transformations to the zinc blende structure during plastic deformation. It is found that there is a correlation between 1/3<10 <span><math><mrow><mover><mn>1</mn><mo>‾</mo></mover></mrow></math></span> 0> dislocations and the zinc blende phase transformation. The study revealed that higher temperatures slightly enhance the plastic deformation of GaN while promoting phase transformation to zinc blende. This research analyzed the deformation and damage mechanisms in GaN crystals during mechanical loading at various temperatures, offering significant theoretical foundations for the production and fabrication of GaN-based devices.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114423"},"PeriodicalIF":3.8,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089604","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}

引用次数: 0

Joule-heating vacuum carbothermal reduction process for efficient and cleaner production of magnesium 焦耳加热真空碳热还原法高效清洁生产镁

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-15 DOI: 10.1016/j.vacuum.2025.114416

Xiao Luo, Peng Zhao, Jiangjiang Li

{"title":"Joule-heating vacuum carbothermal reduction process for efficient and cleaner production of magnesium","authors":"Xiao Luo, Peng Zhao, Jiangjiang Li","doi":"10.1016/j.vacuum.2025.114416","DOIUrl":"10.1016/j.vacuum.2025.114416","url":null,"abstract":"<div><div>The vacuum carbothermal reduction (VCTR) method is emerging as a promising and profitable technology for the preparation of metal magnesium (Mg). However, the conventional VCTR method is energy-intensive and time-consuming due to the separation of the operating steps and sluggish reaction kinetics. Here, we developed a one-step Joule heating vacuum carbothermal reduction (OJHVCTR) method for the preparation of metal Mg directly from dolomite. The experimental parameters including vacuum conditions, C/MgO molar ratio, power density and reaction times are optimized. And a MgO reduction rate of 90.7 % can be achieved within 3.2 min at a C/MgO molar ratio of 3:1 and a power density of 0.46 W mm<sup>−3</sup> in 10 Pa. Contrast experiment and molecular dynamics (MD) simulations demonstrate that the rapid reaction can be ascribed to the enhancement of C atoms diffusion due to the electric field in the OJHVCTR method. Importantly, life-cycle assessment proves that compared to the Pidgeon method and the conventional VCTR method, the novel method can reduce energy consumption by 58 % and 6 % as well as GHG emissions by 58 % and 77 %, respectively. These results suggest that the new method can provide an efficient and cleaner alternative for metal Mg production, which is of great significance for structuring a carbon-neutral society with a sustainable and environmentally friendly energy system.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114416"},"PeriodicalIF":3.8,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144089603","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}

引用次数: 0

Selective growth of c- and a-axis-oriented hydroxyapatite thin films by sputtering 溅射法制备c轴和a轴取向羟基磷灰石薄膜

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-15 DOI: 10.1016/j.vacuum.2025.114409

Yudai Okuno , Shunpei Terakawa , Akira Ujitsugu , Masahiro Ikeda , Kazunori Hayashi , Tsutomu Tanaka , Genshiro Sawa , Takeshi Kohama , Masanobu Kusunoki

引用次数: 0

Development of a continuously maneuverable optics port for high vacuum boundary 高真空边界连续可操作光学端口的研制

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-15 DOI: 10.1016/j.vacuum.2025.114420

Subhra Prakash Dey , Biswaranjan Dikshit , Sanjay Sethi

引用次数: 0

Hybrid GA-ANN modelling for microhardness prediction in FSPed Mg-Y-Nd-Zr alloys using autoencoder-synthesized data 基于自编码器合成数据的混合GA-ANN模型用于FSPed Mg-Y-Nd-Zr合金显微硬度预测

IF 3.8 2区材料科学

Vacuum Pub Date : 2025-05-14 DOI: 10.1016/j.vacuum.2025.114413

Annayath Maqbool , Noor Zaman Khan , Arshad Noor Siddiquee

{"title":"Hybrid GA-ANN modelling for microhardness prediction in FSPed Mg-Y-Nd-Zr alloys using autoencoder-synthesized data","authors":"Annayath Maqbool , Noor Zaman Khan , Arshad Noor Siddiquee","doi":"10.1016/j.vacuum.2025.114413","DOIUrl":"10.1016/j.vacuum.2025.114413","url":null,"abstract":"<div><div>Microhardness plays a critical role in determining the applicability of Mg alloys across various industries. Friction Stir Processing (FSP) refines the microstructure, thereby enhancing the microhardness of the processed material. However, the quantitative relationship between FSP parameters and resulting microhardness remains insufficiently understood. In this study, a machine learning approach was used to model the influence of FSP parameters viz. Tool rotation speed (rpm), traverse speed (mm/min), and shoulder diameter (mm) on the microhardness of Mg-Y-Nd-Zr alloys. The experiment dataset, designed using the Taguchi L<sub>27</sub> orthogonal array, consisted of 27 real data points and was augmented with 200 synthetic samples generated using an autoencoder-based data synthesis technique. A hybrid Genetic Algorithm-optimized Artificial Neural Network (GA-ANN) was developed for microhardness prediction. The GA-ANN model trained on the combined dataset achieved an R<sup>2</sup> score of 0.955 and a mean squared error (MSE) of 0.028, significantly outperforming the model trained on real data, which achieved an R<sup>2</sup> of 0.75. Additionally, the GA-ANN model outperformed several baseline models, including a standard ANN (R<sup>2</sup> = 0.85), linear regression (R<sup>2</sup> = 0.72), and a decision tree regressor (R<sup>2</sup> = 0.74)</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"239 ","pages":"Article 114413"},"PeriodicalIF":3.8,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144070421","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}

引用次数: 0

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