Vacuum最新文献

{"title":"Construction and degradation mechanism of the magnetic CoFe1.95Y0.05O4/Ag/g-C3N4 Z-scheme heterojunction for enhanced photocatalytic activity","authors":"Y. Meng ,&nbsp;G.X. zhang ,&nbsp;D.W. Chen ,&nbsp;M. Xu ,&nbsp;Q.W. Liu ,&nbsp;F.C. Jiao","doi":"10.1016/j.vacuum.2024.113817","DOIUrl":"10.1016/j.vacuum.2024.113817","url":null,"abstract":"<div><div>In this study, a Z-scheme heterojunction CoFe_1.95Y_0.05O₄/Ag/g-C₃N₄ (CFYO/ACN) magnetic nanocomposite was prepared by hydrothermal synthesis. The composite was characterised and analyzed using different characterization tools and its photocatalytic degradation activity towards methylene blue (MB) was investigated. The results showed that the CFYO/ACN photocatalyst compared to CoFe_1.95Y_0.05O₄ (CFYO) and Ag/g-C₃N₄ (ACN), the composite CFYO/ACN had the highest degradation efficiency of MB, which was up to 97 % within 120 min, which was 1.26 and 1.09 times higher than that of ACN and CFYO, respectively. The enhancement of the catalytic performance of CFYO/ACN was attributed to the fact that the heterogeneous junction formation effectively inhibited the complexation of photogenerated carriers. In addition, five consecutive cyclic degradation experiments showed that CFYO/ACN exhibited efficient photocatalytic degradation, stable crystal structure, and easy recycling in the photodegradation process. Finally, the capture experiments confirmed that superoxide radicals (<span><math><mrow><mo>⋅</mo><msubsup><mi>O</mi><mn>2</mn><mo>−</mo></msubsup></mrow></math></span>) and hydroxyl radicals (·OH) play a major role in the degradation process. This study provides an effective strategy for the construction of efficient photocatalysts.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113817"},"PeriodicalIF":3.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the structure evolution of (FeCoNiCu)Nx high-entropy thin film","authors":"Yantao Li ,&nbsp;Ziyuan Luo ,&nbsp;Hua Lan ,&nbsp;Jun Liang ,&nbsp;Deming Huang ,&nbsp;Yu Ni ,&nbsp;Donglin Ma ,&nbsp;Xin Jiang","doi":"10.1016/j.vacuum.2024.113815","DOIUrl":"10.1016/j.vacuum.2024.113815","url":null,"abstract":"<div><div>In this paper, we designed a FeCoNiCu high-entropy system composed of elements with weak nitride-forming tendencies. The (FeCoNiCu)N_x high-entropy films (HEFs) were fabricated using high-power pulsed magnetron sputtering (HPPMS) by adjusting the nitrogen flow rate, and the film structure and mechanical properties were systematically investigated. Upon the introduction of N atoms, the film gradually transitioned from an FCC single-phase to a simple cubic structure, accompanied by an increase in grain size. The simple cubic phase represents a multi-component phase, where N atoms are incorporated into the FeCoNiCu lattice. XPS analysis reveals that all four elements—Fe, Co, Ni, and Cu—combine with N to form weak covalent bonds. As the N content in the film increases, the hardness of the simple cubic (FeCoNiCu)N_x film increased by 33 % compared to the FeCoNiCu alloy film, from 7.9 to 10.5 GPa, which is attributed to the solid solution strengthening effect and phase transition. This work offers new insights into the structural evolution of high-entropy alloy systems composed of weak nitride-forming elements.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113815"},"PeriodicalIF":3.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659453","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}

{"title":"Size dependent mechanical properties and deformation mechanisms in Ti and Zr films","authors":"Zhaoqi Hou ,&nbsp;Tao Wang ,&nbsp;Peipei Wang ,&nbsp;Yuhao Wu ,&nbsp;Wanchang Sun","doi":"10.1016/j.vacuum.2024.113810","DOIUrl":"10.1016/j.vacuum.2024.113810","url":null,"abstract":"<div><div>The nanometallic Ti and Zr monolayer films with various thicknesses ranging from 600 to 2200 nm were prepared by using magnetron sputtering technique. The microstructure results demonstrated that Ti films transformed from hcp to fcc at <em>t</em> ≤ 600 nm, while Zr films were grown with hcp structure of nanocolumnar grain. Moreover, the grain orientation of hcp Ti films changed from (0002) preferred orientation at <em>t</em> = 1200 nm to random orientation at larger thickness. Subsequently, the hardness and strain rate sensitivity of films were explored by nanoindentation. The Hall-Petch relationship is obviously invalid to explain the film thickness dependent hardening behaviors in Ti and Zr films, and the influence of phase structure, orientation and residual stress on nanoindentation hardness was discussed. It seems that residual stress plays an important role in the determination of hardness in present Ti and Zr films. The negative strain rate sensitivity <em>m</em> appeared during the plastic deformation of fcc Ti films, which is caused by the phase transformation. The underlying deformation mechanism of hcp Ti and Zr films was also discussed.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113810"},"PeriodicalIF":3.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659412","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}

{"title":"Comparative analysis of impurity removal in aluminum, copper, and nickel by hydrogen refining","authors":"Yuchong Chen ,&nbsp;Yubo Wang ,&nbsp;Zaijiu Li ,&nbsp;Yue Shen ,&nbsp;Ming Wen ,&nbsp;Sugun Lim ,&nbsp;Qinglin Jin","doi":"10.1016/j.vacuum.2024.113813","DOIUrl":"10.1016/j.vacuum.2024.113813","url":null,"abstract":"<div><div>This study investigates the effects of vacuum and hydrogen atmospheres on the removal of metallic and non-metallic impurities during zone melting of Al, Cu, and Ni. The results show that while hydrogen had minimal impact on metallic impurity removal, it significantly enhanced the elimination of non-metallic impurities, particularly oxygen, in Cu and Ni. The introduction of hydrogen reduced oxygen levels by over 95 % in Ni and 44 % in Cu, and also improved the removal of carbon and sulfur. However, in Al, hydrogen refining proved less effective due to the stability of Al₂O₃ and the tendency of Al to form hydrides.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113813"},"PeriodicalIF":3.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142657337","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}

{"title":"Enhancement of the quality of mc-Si ingot grown by vacuum directional solidification furnace with growth rate increase reducing the cost of the wafer for PV application: Carbon and oxygen analysis","authors":"Sugunraj Sekar ,&nbsp;Srinivasan Manickam ,&nbsp;Ramasamy Perumalsamy","doi":"10.1016/j.vacuum.2024.113816","DOIUrl":"10.1016/j.vacuum.2024.113816","url":null,"abstract":"<div><div>In this paper, we propose a numerical model to investigate the dissolution of oxygen atoms from the porous silica crucible, SiO gas formation, back diffusion of CO gas and segregation of carbon and oxygen during the growth of multi-crystalline silicon (mc-Si) by vacuum directional solidification (VDS) at different growth rates (3, 6 and 9 mm/h) by silt valve opening rate. The dissolution of oxygen decreases during the rapid growth of ingot because the reaction between the molten silicon and the porous silica crucible is constrained. This limitation on oxygen dissolution from the porous silica crucible further diminishes chemical reaction inside the VDS furnace. Consequently, the segregation pattern of the carbon and oxygen is affected at higher growth rate. During the VDS mc-Si growth, a growth rate of 9mm/h yields better quality of the VDS grown mc-Si ingots compared to other growth rates, this rate reduces SiC precipitation and SiO₂ cluster formation due to lower concentration of carbon and oxygen. The obtained carbon concentration minimizes the wire saw defects. Based on these numerical results (9 mm/h), we have implemented experimental work. Prepared samples are analyzed using FTIR spectra and minority carrier lifetime measurements. The effect of oxygen concentration in the samples is analyzed in the minority carrier lifetime measurements. The oxygen and carbon concentrations are calculated by FTIR spectra and their results are compared with the numerical simulation.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113816"},"PeriodicalIF":3.8,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659413","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}

{"title":"Decay of secondary electron yield of MgO–Au composite film at different incident electron energies","authors":"Zhangcong Xia ,&nbsp;Yunrong Wang ,&nbsp;Guofeng Liu ,&nbsp;Tao Deng ,&nbsp;Haodong Wang ,&nbsp;Jie Li ,&nbsp;Wenbo Hu ,&nbsp;Shengli Wu ,&nbsp;Xin Zhong","doi":"10.1016/j.vacuum.2024.113789","DOIUrl":"10.1016/j.vacuum.2024.113789","url":null,"abstract":"<div><div>The relationship between the incident electron energy and secondary electron yield (SEY) decay of MgO–Au composite film was investigated by the designed comparison experiments. Besides the incident current and the properties of the film, the SEY value and the incident electron energy were found to be the other two key factors affecting the SEY decay rate. The value of SEY and the incident electron energy have opposite influences on the SEY decay rate, which makes it necessary to analyze the curve of incident electron energy versus SEY decay rate by dividing it into three parts. In addition, the empirical formulas for SEY decay were derived from experimental data, enabling the estimation of the SEY and decay rate of the MgO–Au composite film at any moment during SEY decay. Furthermore, the cause of SEY decay was also analyzed based on the relationship between incident electron energy and the SEY decay rate. The thermal dissipation, surface roughness, and deposition of contaminants were proven not to be the determinants of SEY decay. The experiment results in this paper supported the inference that the charging effect was the primary cause of SEY decay.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113789"},"PeriodicalIF":3.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659410","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}

{"title":"Changes in electronic structure within NiSx (0.60 < x < 1.53) compound series","authors":"Saroj Dahal,&nbsp;Dhan Rana,&nbsp;Boris Sinkovic","doi":"10.1016/j.vacuum.2024.113806","DOIUrl":"10.1016/j.vacuum.2024.113806","url":null,"abstract":"<div><div>In this article, changes in electronic properties of NiS_<em>x</em> series of films with different sulfur content (<em>x</em> = <em>S/Ni</em>) are studied using X-ray (XPS) and ultra-violet (UPS) photoelectron spectroscopy techniques. NiS_<em>x</em> (0.60 <em>&lt; x &lt;</em> 1.53) films are synthesized on native oxide of Si(111) substrates via reactive deposition of Ni and S in an ultra-high vacuum chamber by varying the sulfur pressures and substrate temperatures. The binding energy (BE) of Ni2<em>p</em>_3<em>/</em>2 core level, the separation between the Ni2<em>p</em>_3<em>/</em>2 main peaks and satellite peaks, and the Ni3<em>d</em> valence band binding energies are all found to vary nearly linearly with the sulfur content in NiS_x series of compounds, suggesting a direct dependence of Ni electronic charge on the sulfur content. The shift of the Ni3d and S3p states (to higher and lower BE, respectively) with an increase in the S content provides experimental confirmation of the theoretical prediction previously reported (Wen et al., 2020) [1]. All NiS_<em>x</em> films showed density of states (DOS) at the Fermi level, indicating their metallic nature. The Ni2<em>p</em>_3<em>/</em>2 binding energy shift of NiS_<em>x</em> films are much smaller than that of oxide-based compounds, confirming the significantly more covalent nature of the sulfides. NiS_x film grown on Si (111) substrate showed nickel silicide interface formation. This study provides information on the growth and trends in the electronic properties of NiS_<em>x</em> relevant for their applications in catalysis, energy storage, and electronic devices.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113806"},"PeriodicalIF":3.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659407","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}

{"title":"Baric exothermic fragmentation of crystals","authors":"Mahach N. Magomedov","doi":"10.1016/j.vacuum.2024.113814","DOIUrl":"10.1016/j.vacuum.2024.113814","url":null,"abstract":"<div><div>Currently, an extensive study of the properties of matter at high pressures is underway. However, little attention is paid to the baric fragmentation of the crystal. Our work is devoted to the study of the nature of this effect. Based on the analytical method (i.e. without computer simulation), the change in the specific (per unit area) surface energy (σ) of the crystal from the normalized volume (<em>v</em>/<em>v</em>_o) along various isotherms was studied. It is shown that there is a maximum on the isotherm σ(<em>v</em>/<em>v</em>_o), with (<em>v</em>/<em>v</em>_o)_max &lt; 1. With an isothermal deviation (at decreasing or increasing) of the <em>v</em>/<em>v</em>_o value from the (<em>v</em>/<em>v</em>_o)_max, the σ(<em>v</em>/<em>v</em>_o) function decreases, passing at certain values, (<em>v</em>/<em>v</em>_o)_<em>frS</em> &lt; (<em>v</em>/<em>v</em>_o)_max &lt; 1 or (<em>v</em>/<em>v</em>_o)_<em>frL</em> &gt; 1, to the negative values. This behavior of the σ(<em>v</em>/<em>v</em>_o) function at <em>v</em>/<em>v</em>_o &lt; (<em>v</em>/<em>v</em>_o)_<em>frS</em> or <em>v</em>/<em>v</em>_o &gt; (<em>v</em>/<em>v</em>_o)_<em>frL</em> should cause spontaneous fragmentation of the crystal, in which the crystal will strive in any way to increase its specific (per atom) surface: either free (when stretched), or intercrystalline (when compressed). It is indicated that the crystal under all-round stretching passes into the liquid or gas phase without reaching the (<em>v</em>/<em>v</em>_o)_<em>frL</em> value. However, a negative value of the surface energy can be achieved with all-round compression of the crystal. It is shown that the negative value of the σ(<em>v</em>/<em>v</em>_o) function should stimulate both fragmentation of the crystal structure and heating of the fragmenting medium (exothermic effect) and the appearance of additional pressure in this medium due to the appearance of the inner surface. Calculations of (<em>v</em>/<em>v</em>_o)_max and (<em>v</em>/<em>v</em>_o)_<em>frS</em> values for Ne, Li and Au crystals at different temperatures have been performed. Based on the experimental data, the pressures are indicated, which correspond to the calculated (<em>v</em>/<em>v</em>_o)_<em>frS</em> values. It was shown that these static pressures are quite achievable in modern experiments.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113814"},"PeriodicalIF":3.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659416","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}

{"title":"Effect of B/N dual doping on mechanical and tribological properties of Mo-S-B-N sputtered films","authors":"Ningxin Wei ,&nbsp;Hang Li ,&nbsp;Jianliang Li ,&nbsp;Jiewen Huang ,&nbsp;Jian Kong ,&nbsp;Qiujie Wu ,&nbsp;Huaping Tan ,&nbsp;Yan Shi ,&nbsp;Dangsheng Xiong","doi":"10.1016/j.vacuum.2024.113803","DOIUrl":"10.1016/j.vacuum.2024.113803","url":null,"abstract":"<div><div>Doping with non-metal element is effective to improve the porous morphology and enhance the mechanical and tribological properties of transition metal dichalcogenides (TMDs) based film. However, the mechanical properties of TMDs based film with single additive should be enhanced further for better wear resistance. In this work, B/N dual-doping was used to further enhance the deformation resistance and toughness of MoS₂ based films deposited by magnetron sputtering, while the effect of B/N dopants on the structure, mechanical and tribological properties has been investigated. Mo-S-B-N film with B content of 20.91 at. % and N content of 18.13 at. % consists of MoS₂ and amorphous nitride/boride, in which B/N dual doping film forms a higher ordered MoS₂ lamellar structure compared to B doping film. With a hardness of 11.6 ± 0.9 GPa and improved toughness, the film achieves a low wear rate and average friction coefficient is achieved. Comparing B/N dual doping film to B doping film, the stable formation of tribolayer with more strengthened deformation resistance results in the steady friction and the improved wear resistance, while the limited TMDs reorientation leads to the slight increase of friction coefficient.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113803"},"PeriodicalIF":3.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659510","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}

{"title":"Ordered mesoporous CrCeOx catalyst prepared by hard template for toluene and formaldehyde combustion","authors":"Minghui Guo,&nbsp;Bao Tian,&nbsp;Limin Si,&nbsp;Xinying Zhang,&nbsp;Yunsheng Xia","doi":"10.1016/j.vacuum.2024.113811","DOIUrl":"10.1016/j.vacuum.2024.113811","url":null,"abstract":"<div><div>The <em>meso</em>-Cr-Ce catalysts with different proportions of chromium and cerium were prepared using three-dimensional ordered mesoporous silica (KIT-6) as hard template by vacuum assisted impregnation method. The physicochemical properties of the catalysts were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), nitrogen adsorption-desorption (BET), transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and temperature programmed reduction (TPR) techniques. The oxidation removal performance of toluene and formaldehyde was evaluated. The results show that all catalysts have better catalytic oxidation activity than the bulk counterpart. The <em>meso</em>-Cr-Ce-1 catalyst of same Cr/Ce molar ratio was larger in surface area (up to 186 m²/g) and could be reduced at lower temperatures, and exhibited the highest catalytic oxidation performance. At 30,000 h⁻¹ of space velocity and 1000 ppm of VOC, toluene and formaldehyde conversions reached 90 % at 240 and 160 °C, respectively, and the apparent activation energies were 64.1 and 37.2 kJ/mol. The excellent performance of the catalyst is associated with its well-developed mesoporous structure, high specific surface area, good low temperature reducibility and dispersion and synergistic effect of active components.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"231 ","pages":"Article 113811"},"PeriodicalIF":3.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659494","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}