IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-10 DOI: 10.1016/j.vacuum.2025.114998

Junyi Wang , Ruijie Song , Yan Chen , Shanjun Chen , Jie Hou , Song Li , Weibin Zhang

The first-principles method are employed to explore the structural, optoelectronic, mechanical, dynamic, and thermodynamic properties of cubic BaXCl₃ (X = Fe, Co, Ni) for the first time. The calculated elastic constants and formation energies demonstrate that all BaXCl₃ compounds own mechanical and thermodynamic stability, and the tolerance factors confirm their structural stability. The Poisson's ratios indicate that these compounds exhibit metallic bonding characteristics. The analysis of electronic properties indicates that BaFeCl₃ and BaNiCl₃ exhibit half-metallic behavior, while BaCoCl₃ exhibits semiconducting behavior. Furthermore, these compounds are fully spin-polarized, achieving a polarization rate of 100 %, which highlights their significant potential for applications in spintronic devices. The optical properties reveal that BaFeCl₃ and BaNiCl₃ are high refractive index materials with static refractive index values of 6.04 and 3.14, respectively. Notably, BaXCl₃ exhibit high transmittance in the visible light region and superior absorption capabilities in the deep ultraviolet region, while BaCoCl₃ exhibits a reflectivity lower than 10 % in low energy (<5.0 eV). The absence of imaginary frequencies in the phonon dispersions confirms the dynamic stability of BaXCl₃. Additionally, the heat capacities at constant volume of BaXCl₃ approach the Dulong-Petit limit at high temperatures, according to the analysis based on the quasi-harmonic Debye model.

首次采用第一性原理方法对立方BaXCl3 （X = Fe, Co, Ni）的结构、光电、力学、动力学和热力学性质进行了研究。计算得到的弹性常数和形成能表明，所有BaXCl3化合物都具有力学和热力学稳定性，容差系数证实了它们的结构稳定性。泊松比表明这些化合物具有金属键特性。电子性能分析表明，BaFeCl3和BaNiCl3表现为半金属行为，而BaCoCl3表现为半导体行为。此外，这些化合物是完全自旋极化的，极化率达到100%，这突出了它们在自旋电子器件中的应用潜力。光学性质表明，BaFeCl3和BaNiCl3是高折射率材料，其静态折射率分别为6.04和3.14。值得注意的是，BaXCl3在可见光区具有较高的透过率，在深紫外区具有较好的吸收能力，而BaCoCl3在低能量（<5.0 eV）的反射率低于10%。声子色散中不存在虚频率，证实了BaXCl3的动态稳定性。此外，基于准调和Debye模型的分析表明，在高温下，BaXCl3的等体积热容接近Dulong-Petit极限。

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引用次数: 0

Impact of oxygen-related defects in a thin AlN layer on the two-dimensional electron gas in an AlN/GaN heterostructure AlN薄层中氧相关缺陷对AlN/GaN异质结构中二维电子气体的影响

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-09 DOI: 10.1016/j.vacuum.2025.114999

Y.E. Maidebura , T.V. Malin , V.G. Mansurov , V.A. Golyashov , D.S. Milakhin

This study investigates the impact of oxygen-related defects in thin AlN barrier layers on the electronic properties of AlN/GaN heterostructures for GaN-based high-electron-mobility transistors (HEMTs). AlN/GaN heterostructures with and without in situ SiN passivation were grown by ammonia molecular beam epitaxy and characterized by reflection high-energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). RHEED and AFM analyses indicate that the AlN/GaN layers exhibit an atomically smooth morphology with no evidence of dislocation networks, while XRD confirms the high crystalline quality of the GaN active layer. Nevertheless, Hall effect measurements reveal a pronounced reduction in two-dimensional electron gas (2DEG) mobility in uncovered AlN layers, despite comparable carrier concentrations. XPS analysis demonstrates that in SiN-covered AlN, oxygen predominantly forms low-coordinated Al–O configurations corresponding to point-like defects, whereas uncovered AlN exhibits highly coordinated Al–O states characteristic of Al₂O₃-like extended defects. These findings indicate that SiN passivation does not fully prevent oxidation but effectively suppresses oxygen diffusion, limiting extended oxide defect formation near the AlN/GaN interface. The results emphasize the critical role of AlN surface oxidation in determining 2DEG mobility and provide valuable guidance for optimizing passivation strategies in high-performance enhancement-mode GaN HEMTs.

本文研究了氮化镓基高电子迁移率晶体管（HEMTs）中氮化镓阻挡层中氧相关缺陷对氮化镓/氮化镓异质结构电子性能的影响。采用氨分子束外延法生长了原位钝化和未原位钝化的AlN/GaN异质结构，并用反射高能电子衍射（RHEED）、原子力显微镜（AFM）、x射线衍射（XRD）和x射线光电子能谱（XPS）对其进行了表征。RHEED和AFM分析表明，AlN/GaN层表现出原子光滑的形貌，没有位错网络的证据，而XRD证实了GaN活性层的高结晶质量。然而，霍尔效应测量显示，尽管载流子浓度相当，但在未覆盖的氮化铝层中，二维电子气（2DEG）迁移率明显降低。XPS分析表明，在sin覆盖的AlN中，氧主要形成低配位的Al-O构型，对应于点状缺陷，而未覆盖的AlN则表现出高配位的Al-O态，特征为al2o3类扩展缺陷。这些发现表明，SiN钝化不能完全阻止氧化，但能有效抑制氧扩散，限制了AlN/GaN界面附近氧化缺陷的扩展。结果强调了AlN表面氧化在决定2DEG迁移率中的关键作用，并为优化高性能增强模式GaN hemt的钝化策略提供了有价值的指导。

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引用次数: 0

Achieving high wear-resistance MIM Ti6Al4V alloy via the controlled growth of nitride layer in vacuum gas nitriding 在真空气体氮化过程中，通过控制氮层生长来获得高耐磨性能的MIM Ti6Al4V合金

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-08 DOI: 10.1016/j.vacuum.2025.114991

Xinjing Wang , Jianzhuo Sun , Guanghao Shi , Yu Pan , Ranpeng Lu , Yanjun Liu , Fan Kuang , Xin Lu

Complex-shaped Ti6Al4V (Ti64) alloy components fabricated via metal injection molded (MIM) technology exhibit high specific strength and cost-effectiveness, making them promising for aerospace and digital electronics applications. However, poor wear resistance, which significantly deteriorates the structural safety and service life of MIM components, remains a stern challenge for MIM titanium (Ti) alloys. Here, we propose an innovative strategy to develop Ti64 alloy with a spatially heterogeneous distribution of dual-phase nitrides by investigating their evolution behavior through thermodynamic kinetics and elucidating the contribution of individual nitride phases to wear resistance. The dual-phase structure (TiN + Ti₂N) is successfully fabricated in Ti64 alloy by vacuum gas nitriding technique. The fabricated 900°C-treated sample has a continuous and dense compound layer with a thickness of 6.84 nm existing on the top of nitrogen diffusion zone. It displays the best wear resistance with a reduced wear rate of 0.8 × 10⁻¹³ m³/Nm (90 % decrease compared to the untreated substrate). The corresponding wear mechanism is transitioned from the plastic deformation and adhesive wear to the abrasive wear. These findings suggest that the wear resistance of the nitrided layer is collectively influenced by the phase evolution behavior, microstructure, relative content, and spatial distribution of phases during nitriding. By employing a multiscale structural design strategy, the distinct advantages of TiN and Ti₂N phases are leveraged to achieve an optimal balance between high hardness and low surface roughness. These findings are expected to break the conventional hardness-roughness trade-off dictated by the natural phase evolution and provide insights for the compositional design and performance optimization of MIM Ti alloys under high wear conditions.

通过金属注射成型（MIM）技术制造的复杂形状的Ti6Al4V （Ti64）合金部件具有高比强度和成本效益，使其在航空航天和数字电子应用中具有前景。然而，较差的耐磨性严重影响了MIM构件的结构安全性和使用寿命，是MIM钛合金面临的严峻挑战。在此，我们提出了一种创新的策略，通过热力学动力学研究双相氮化物的演化行为，并阐明单个氮化物相对耐磨性的贡献，来开发具有空间非均匀分布的Ti64合金。采用真空气体氮化技术在Ti64合金上成功制备了TiN + Ti2N双相组织。900℃处理后的样品在氮扩散区顶部有一层厚度为6.84 nm的连续致密的化合物层。其耐磨性最好，磨损率降低了0.8 × 10−13 m3/Nm（与未处理的基材相比降低了90%）。相应的磨损机制由塑性变形、黏着磨损向磨粒磨损过渡。结果表明，渗氮过程中相的演化行为、微观组织、相对含量和空间分布共同影响了渗氮层的耐磨性。通过采用多尺度结构设计策略，利用TiN和Ti2N相的独特优势来实现高硬度和低表面粗糙度之间的最佳平衡。这些发现有望打破由自然相演化决定的传统硬度-粗糙度权衡，并为高磨损条件下MIM Ti合金的成分设计和性能优化提供见解。

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引用次数: 0

Comprehensive simulation insights into molten pool dynamics, stress, and temperature fields of vacuum electron beam welded CoCrFeMnNi HEA/SA203 joints 真空电子束焊接CoCrFeMnNi HEA/SA203接头熔池动力学、应力和温度场的综合模拟研究

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-08 DOI: 10.1016/j.vacuum.2025.114987

Teng Xinyan , Chen Guoqing , Gan Zhanhua , Zhu Likuo , Zhao Junhong , Yang Chen , Leng Xuesong

This study joins CoCrFeMnNi HEA/SA203 steel dissimilar materials using vacuum electron beam welding (VEBW), achieving a joint strength of 87 % of the base material. However, despite this high mechanical strength, the joint is compromised by pronounced morphological undulations along the HEA-side fusion line, posing potential risks. Through a validated multi-physics simulation, we demonstrate that this defect is not due to compositional variations but is a direct consequence of the intrinsic thermophysical property mismatch between the materials. The HEA's poor thermal conductivity and high molten-state viscosity create severe asymmetric thermal-flow fields, establishing a dynamic instability within the molten pool. This instability is characterized by the convergence of stratified vortices and a periodic, high-velocity mass exchange, which is identified as the direct mechanism responsible for sculpting the irregular fusion line. The simulation results demonstrate excellent agreement with experimental microstructures and morphologies, validating the proposed mechanism. This work provides a fundamental understanding of the molten pool dynamics governing defect formation in dissimilar metal welding involving HEAs, offering a theoretical basis for mitigating such defects and advancing the reliable application of HEA-based cryogenic components.

本研究采用真空电子束焊接（VEBW）连接CoCrFeMnNi HEA/SA203钢异种材料，接头强度达到母材的87%。然而，尽管具有很高的机械强度，但沿hea侧融合线明显的形态波动损害了关节，带来了潜在的风险。通过验证的多物理场模拟，我们证明了这种缺陷不是由于成分变化，而是材料之间固有热物理性质不匹配的直接后果。HEA的低导热性和高熔融状态粘度造成了严重的不对称热流场，在熔池内建立了动态不稳定性。这种不稳定性的特征是分层涡的收敛和周期性的高速质量交换，这被认为是造成不规则融合线的直接机制。模拟结果与实验的微观结构和形貌吻合良好，验证了所提出的机理。本研究为了解含HEAs的异种金属焊接缺陷形成的熔池动力学提供了基础，为减轻此类缺陷和推进基于HEAs的低温元件的可靠应用提供了理论基础。

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引用次数: 0

Effect of Ti layer on deformation ability and damage mechanism of diamond-like carbon coated aluminum alloy Ti层对类金刚石碳涂层铝合金变形能力及损伤机理的影响

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-08 DOI: 10.1016/j.vacuum.2025.114997

Yanjin Li , Xin Zhang , Silong Zhang , Hao Li , Rende Chen , Kazuhito Nishimura , Peng Guo , Aiying Wang

Ti interlayer effectively improves the protective performance of Diamond-like carbon (DLC) coatings for Al-based alloys, by compensating for their large interfacial mismatch. However, optimization of the Ti interlayer has largely remained trial-and-error approaches, because the interface behavior under external loading has not been systematically revealed. Here, DLC around 1 μm were deposited on Al alloys with Ti interlayer, whose microstructure was varied by changing its thickness from 0.15 to 0.97 μm. Results demonstrated that the thickness of Ti layer had little effect on the intrinsic structure of DLC, with a critical thickness of 0.75 μm, the Ti can effectively reduce the stress and enhance hardness of systems. Interfacial structure analysis after indentation testing affirmed that, the plastic deformation ability of Al/Ti/DLC was increased and the cracking of DLC layer towards inside was significantly suppressed. However, thin Ti layers failed to alleviate stress concentration at the Ti/DLC interface, and Ti layers thicker than the critical value developed the stronger (0002) phase orientation, which in turn sacrificed the grain boundary bonding and was destructive to its load-bearing capacity. These findings demonstrated that the Ti layer with dense structure was extremely crucial for achieving high-performance DLC coatings on Al alloys.

Ti中间层通过补偿al基合金中较大的界面失配，有效地提高了类金刚石涂层对al基合金的保护性能。然而，钛中间层的优化在很大程度上仍然是试错的方法，因为界面在外部载荷下的行为尚未被系统地揭示。在厚度为0.15 ~ 0.97 μm的Ti夹层铝合金上沉积了厚度约为1 μm的DLC。结果表明，Ti层的厚度对DLC的本征结构影响不大，当Ti层的临界厚度为0.75 μm时，Ti层可以有效降低体系的应力，提高体系的硬度。压痕试验后的界面结构分析证实，Al/Ti/DLC的塑性变形能力增强，DLC层向内开裂得到明显抑制。然而，薄Ti层未能缓解Ti/DLC界面处的应力集中，厚度大于临界值的Ti层形成了更强的（0002）相取向，从而牺牲了晶界结合，破坏了其承载能力。这些发现表明，致密结构的Ti层对于在铝合金上实现高性能DLC涂层至关重要。

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引用次数: 0

Enhancing the reliability of SiC MOS capacitors by optimizing the surface treatment process for etched silicon carbide 通过优化蚀刻碳化硅表面处理工艺，提高SiC MOS电容器的可靠性

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-08 DOI: 10.1016/j.vacuum.2025.114993

Junzhe Liu , Haihui Wang , Shengsheng Wei , Weiwei Xie , Yue Li , Fuwen Qin , Dejun Wang

The etched SiC surface suffers from issues such as surface damage and contamination, which severely affects the reliability of the Metal-Oxide-Semiconductor (MOS) devices fabricated therefrom. In this work, we propose an improved process that introduces electron cyclotron resonance (ECR) microwave hydrogen plasma surface treatment as an additional post-treatment step after sacrificial oxidation (a conventional post-etch treatment process), followed by thermal oxidation for oxide layer formation. Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) analyses revealed that this process improves surface morphology while effectively removing surface elemental contamination. Electrical testing results demonstrate that MOS capacitors fabricated using this method exhibit significantly reduced interface trap density, enhanced breakdown characteristics of SiO₂ films, and improved bias temperature instability (BTI).

蚀刻SiC表面存在表面损伤和污染等问题，严重影响了其制造的金属氧化物半导体（MOS）器件的可靠性。在这项工作中，我们提出了一种改进的工艺，在牺牲氧化（传统的蚀刻后处理工艺）之后，引入电子回旋共振（ECR）微波氢等离子体表面处理作为附加的后处理步骤，然后进行热氧化以形成氧化层。原子力显微镜（AFM）和x射线光电子能谱（XPS）分析表明，该工艺改善了表面形貌，同时有效地去除了表面元素污染。电学测试结果表明，使用该方法制备的MOS电容器具有显著降低界面陷阱密度、增强SiO2薄膜击穿特性和改善偏置温度不稳定性（BTI）的特点。

引用次数: 0

Editorial Board and Vacuum units 编辑委员会和真空单位

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-06 DOI: 10.1016/S0042-207X(25)00966-2

引用次数: 0

Effect of different modes of electron-beam processing on structure, surface properties, corrosion resistance and martensitic transformations of TiNi-based alloy 不同电子束处理方式对镍基合金组织、表面性能、耐蚀性和马氏体相变的影响

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-06 DOI: 10.1016/j.vacuum.2025.114994

N.V. Artyukhova , S.G. Anikeev , A.V. Shabalina , E.A. Bolshevich , S. Pakholkina , V.V. Stolyarov , S.A. Kulinich

This paper investigates the influence of electron-beam treatment on the surface structure, corrosion resistance, and properties of monolithic TiNi-based alloys, both with and without an oxide layer. Initial monolithic TiNi alloy plates featuring a surface oxide layer were produced by vacuum induction melting followed by ingot rolling. The oxide layer was removed using chemical etching in an aqueous solution of nitric and hydrofluoric acids. Electron-beam processing was conducted at energy densities of 3.5 and 4.5 J/cm² with 15 pulses per sample. The surface structure of the plates before and after electron-beam treatment was analyzed using X-ray diffraction, optical and scanning electron microscopy. Wettability was assessed via the sessile droplet method using a drop shape analyzer, and surface roughness parameters were evaluated by means of interference profilometry. Mechanical surface properties were characterized by the Oliver–Pharr method, while corrosion behavior was determined through measurements of corrosion current, corrosion potential, and corrosion rate. Electron-beam exposure was found to modify the surface structural and phase composition, enhancing its homogeneity. An increase in electron energy during treatment reduced surface roughness, which resulted in an increase in water contact angle values. At the same time, the characteristic temperatures of martensitic transformations remained largely unchanged.

本文研究了电子束处理对整体镍基合金的表面结构、耐蚀性和性能的影响，无论是否有氧化层。采用真空感应熔炼后轧锭的工艺生产了表面有氧化层的TiNi合金整体板。用化学蚀刻法在硝酸和氢氟酸水溶液中除去氧化层。电子束处理分别在3.5和4.5 J/cm2的能量密度下进行，每个样品15个脉冲。利用x射线衍射、光学显微镜和扫描电镜对电子束处理前后的表面结构进行了分析。使用液滴形状分析仪通过固滴法评估润湿性，使用干涉轮廓术评估表面粗糙度参数。机械表面性能通过Oliver-Pharr法表征，腐蚀行为通过腐蚀电流、腐蚀电位和腐蚀速率测量来确定。发现电子束照射可以改变表面结构和相组成，增强其均匀性。处理过程中电子能量的增加降低了表面粗糙度，从而导致水接触角值的增加。同时，马氏体相变的特征温度基本保持不变。

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引用次数: 0

Engineering lithium-decorated 2D-AlB4 monolayer for hydrogen storage applications 用于储氢应用的工程锂装饰2D-AlB4单层

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-06 DOI: 10.1016/j.vacuum.2025.114996

H. Ouhenou, M. Agouri, A. Waqdim, S. Elfilali, Y. Mekaoui, A. Abbassi, S. Taj, B. Manaut

The search for efficient hydrogen storage materials has driven scientific research toward suitable two-dimensional materials with high gravimetric capacity and favorable physisorption properties. In this study, we investigate a lithium-decorated 2D-AlB₄ monolayer as a potential candidate for solid-state hydrogen storage. Our findings reveal that the AlB₄ monolayer exhibits excellent structural stability and metallic behavior. During the lithiation process, the lithium adatom demonstrates a strong adsorption energy of approximately

-

3.9424 eV, which exceeds the cohesive energy of lithium, effectively preventing lithium-clustering. Furthermore, lithium decoration significantly enhances the adsorption of H₂ molecules, with an average adsorption energy of about -0.19 eV per molecule, meeting the U.S. Department of Energy (DOE) recommendations for practical hydrogen storage. Additionally, the corresponding desorption temperature is determined to be 141 K. These results suggest that AlB₄, when carefully engineered with lithium metal decoration, can serve as an efficient material for hydrogen storage applications.

对高效储氢材料的探索推动了科学研究朝着具有高重量容量和良好物理吸附性能的合适二维材料的方向发展。在这项研究中，我们研究了锂修饰的2D-AlB4单层作为固态储氢的潜在候选材料。我们的研究结果表明，al4单层具有优异的结构稳定性和金属性能。在锂化过程中，锂原子表现出较强的吸附能，约为- 3.9424 eV，超过了锂的黏结能，有效地防止了锂的聚簇。此外，锂修饰显著增强了对H2分子的吸附，平均吸附能约为-0.19 eV /分子，符合美国能源部（DOE）对实际储氢的建议。测定了相应的解吸温度为141 K。这些结果表明，当精心设计与锂金属装饰时，al4可以作为储氢应用的有效材料。

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引用次数: 0

Preparation of hierarchical Si3N4/BN ceramic aerogel with nanofibrous-granular composite structure for potential adsorbent applications 纳米纤维颗粒复合结构氮化硼/氮化硼陶瓷气凝胶的制备及其在吸附剂中的应用前景

IF 3.9 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2025-12-05 DOI: 10.1016/j.vacuum.2025.114990

Lei Han , Ruling Du , Chenyang Xi , Longhao Dong

Pharmaceuticals are emerging contaminants causing a lot of concerns and posing a threat to the aquatic environment and human health. In this study, hierarchical Si₃N₄/BN ceramic aerogel (SN-BN CA) adsorbents with nanofibrous-granular composite structures comprising BN fibers and Si₃N₄ were prepared at a relatively low temperature of 1473 K for 2 h via a foam-gelcasting combined in-situ nitridation route, employing Si, melamine, and boric acid as raw materials, and tested as an adsorbent for the removal of pharmaceutical ciprofloxacin (CIP) and atenolol (ATL) from its aqueous solutions. The density and compressive strength of the as-prepared SN-BN CA were respectively 0.17 g/cm³ and 0.74 MPa. They exhibited a rapid adsorption rate and effective removal performance (>97 %) for CIP and ATL under the experimental conditions of C₀ = 10 mg/L, pH = 7 and 295 ± 3 K, even at a low adsorbent dose of 250 mg/L. The maximum adsorption capacity of the composite foam were respectively 23.6 mg/g and 18.4 mg/g at the CIP and ATL concentration of 10 mg/L. The as-prepared SN-BN CA composites with robust strength, good recyclability and high efficiency in the CIP and ATL removal, could be a promising candidate for efficient removal of a range of similar emerging contaminants.

药物是一种新兴的污染物，引起了人们的广泛关注，对水生环境和人类健康构成了威胁。本研究以硅、三聚氰胺和硼酸为原料，在1473 K的相对低温条件下，采用泡沫-凝胶浇铸结合原位氮化的方法，制备了纳米纤维-颗粒复合结构的氮化硼/氮化硼陶瓷气凝胶（SN-BN CA）吸附剂，并对其水溶液中的药物环丙沙星（CIP）和阿替洛尔（ATL）进行了脱除试验。SN-BN CA的密度和抗压强度分别为0.17 g/cm3和0.74 MPa。在C0 = 10 mg/L、pH = 7、295±3k的实验条件下，即使在低吸附剂剂量为250 mg/L的情况下，它们对CIP和ATL也表现出快速的吸附速率和有效的去除性能（> 97%）。在CIP和ATL浓度为10 mg/L时，复合泡沫的最大吸附量分别为23.6 mg/g和18.4 mg/g。所制备的SN-BN - CA复合材料具有强度强、可回收性好、去除CIP和ATL效率高的特点，是高效去除一系列类似新兴污染物的有希望的候选材料。

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引用次数: 0

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