Hydrogen adsorption mechanism on non-evaporable getter ternary alloy Ti-V-Nb surface

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum Pub Date : 2025-02-28 DOI:10.1016/j.vacuum.2025.114203

Alvin Kambondo , Jie Wang , Kaan Yigit , Qingyu Si , Yanyang Qin , Yaqiong Su , Runxia Zhang , Huaying Wu , Chenyu Liang , Sheng Wang

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引用次数: 0

Abstract

Non evaporable getter coatings are essential for achieving ultra-high vacuum (UHV) and extremely high vacuum (XHV) conditions in high-energy particle accelerators, with hydrogen (H₂) being a major residual gas of concern. This research uses Density Functional Theory (DFT) to investigate the adsorption of H₂ molecules on the Ti-V-Nb (110) surface, maintaining a 1:1:1 elemental ratio of Ti-V-Nb. The analysis prioritizes adsorption sites based on factors such as adsorption energy, H-H bond length, and charge redistribution. The results show that hydrogen molecules preferentially adsorb at the Hollow site > Bridge site > Top site, with corresponding variations in adsorption energies and bond lengths. The partial density of states (PDOS) calculations reveals significant hybridization between the H₂ molecule and the Ti-V-Nb (110) surface at each adsorption site, confirming the formation of strong chemical bonds. Mulliken charge population analysis results highlight significant charge redistribution upon adsorption, indicative of chemisorption phenomena. Bond population analysis confirms covalent bonding between H atoms and surface metals. The H-H bond length indicates nondissociation at the V top site (0.97Å) and dissociation at the Ti-V bridge (2.28 Å) and Ti-V-Nb hollow (2.73 Å) sites. Electron density difference calculations further confirm the activation mechanism of H₂ molecules on the Ti-V-Nb (110) surface by showing the accumulation and depletion of charges on H₂ at the selected sites. These insights contribute to understanding the hydrogen adsorption mechanism on Ti-V-Nb surfaces, which can enhance the efficiency of NEG coatings for achieving UHV and XHV conditions in high-energy particle accelerators.

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来源期刊

Vacuum 工程技术-材料科学：综合

CiteScore

6.80

自引率

17.50%

发文量

审稿时长

34 days

期刊介绍： Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences. A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below. The scope of the journal includes: 1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes). 2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis. 3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification. 4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.