K改性NiAl类水滑石衍生复合氧化物催化分解N2O

制备了Ni/Al=4.1(原子比)的NiAl类水滑石,焙烧获得NiAl复合氧化物,浸渍K2CO3溶液制备了K改性NiAl复合氧化物催化剂,其中K/Ni=0.05~0.2(原子比),用于N2O催化分解反应.通过元素分析、XRD、BET、H2-TPR、XPS等技术表征了催化剂的组成结构,考察了NiAl类水滑石的预处理方式、...     

Aligning one-dimensional arrays of nanoclusters on a thin film of Al2O3 grown on vicinal NiAl surfaces

We present a self-organised approach for the synthesis of one-dimensional (1D) arrays of supported nanoclusters. By oxidising NiAl surfaces vicinal to the (1 0 0) plane tilted along the crystallographic direction [0 1 0], we produced ordered thin films of θ-Al₂O₃ that exhibit uniform protrusion stripes propagating uniquely along direction [0 0 1] of the NiAl. These protrusions are preferential centres for nucleation of metal deposited from a vapour; the nanoclusters grown from such metal are aligned and form massive 1D cluster arrays along direction [0 0 1]. The arrays of Co nanoclusters exhibit a diameter as small as 3 nm and length exceeding a micrometer. The results imply prospective applications for which a patterned assembly of nanoclusters is desired.     

ON CORE STRUCTURE PROPERTIES AND PEIERLS STRESS OF DISSOCIATED SUPERDISLOCATIONS IN ALUMINIDES: NiAl AND FeAl

<正>The study of dislocation properties in B2 structure intermetallics NiAl and FeAl is crucial to understand their mechanical behaviors.In this paper,the core structure and Peierls stress of collinear dissociated〈111〉{110} edge superdislocations in NiAl and FeAl are investigated with the modified P-N dislocation equation.The generalized stacking fault energy curve along〈111〉direction in {110} slip plane contains two modification factors that can assure the antiphase energy and the unstable stacking fault energy to change independently.The results show that the core width of superpartials decreases with the increasing unstable stacking fault energy,and increases with the increasing antiphase boundary energy.The calculated Peierls stress of〈111〉{110} edge superdislocations in NiAl and FeAl are 475 MPa and 3042 MPa,respectively.The values of Peierls stress in NiAl is in accordance in magnitude with the experimental and the molecular statics simulations results.     

A first‐principles study of diatomic NiAl: Ground state,structure, and spectroscopic constants

A computational study of diatomic NiAl is reported. Molecular properties evaluated include the equilibrium bond length (r_e), equilibrium stretching frequency (ω_e), doublet‐quartet energy splitting, and nickel‐aluminum bond strength. Several interesting conclusions have resulted from this research. First, convergence in calculated properties is smoother with recently reported correlation consistent basis sets than earlier basis sets for Ni and Al. Second, with the exception of bond strength, basis set limit properties extrapolated using correlation basis sets are in agreement with reported data. Third, this research suggests that caution may be needed with regard to the use of DFT for developing interatomic potentials for larger scale simulations. For example, B97‐1 showed better agreement with reported r_e for ²NiAl than B3LYP. However, the situation was reversed for the calculation of ω_e. With respect to bond strength, the situation is unclear due to the scatter among experiment and calculations. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Growth of Al2O3 thin films on NiAl(1 0 0) by gas-phase oxidation and electro-oxidation

The growth and structures of aluminum oxides on NiAl(1 0 0) have been investigated by RHEED (reflection high energy electron diffraction), complemented by LEED (low energy electron diffraction), AES (Auger electron spectroscopy) and STM (scanning tunneling microscopy). Crystalline θ-Al₂O₃ phase grows through gas-phase oxidation on the NiAl(1 0 0) substrate with its a and b-axes parallel to [0 −1 0] and [0 0 1] direction of the substrate, respectively, forming a (2 × 1) unit cell. Whilst, three-dimensional nano-sized NiAl(1 0 0) protrusions and Al₂O₃, NiAl(0 1 1) clusters were found to co-exit at the surface, evidenced by extraordinary transmission spots superposed to the substrate reflection rods in the RHEED patterns. Particularly, the NiAl(0 1 1) clusters develop with their (0 1 1) plane parallel to the NiAl(1 0 0) surface, and [1 0 0] axis parallel to the [0 −1 1] direction of the substrate surface. STM observation combined with information from AES and TPD (temperature programmed desorption) suggest the formation of these 3D structures is closely associated with partial decomposition of the crystalline oxides during annealing. On the other hand, smoother (2 × 1) oxide islands with thickness close to a complete monolayer of θ-Al₂O₃ can be formed on NiAl(1 0 0) by electro-oxidation, in contrast with the large crystalline films formed by gas-oxidation.     

Oxidation behavior of NiAl alloy at low temperatures

Oxidation behavior of NiAl alloy at low temperatures was studied. A NiAl plate was oxidized by exposure to ambient atmosphere at room temperature, heated at 473 K in air, and heated at 773 K in air. The oxide formed on the NiAl surface was investigated by angle‐resolved X‐ray photoelectron spectroscopy (AR‐XPS). Chemical composition and atomic concentration in the oxide layer were analyzed with factor analysis of XPS spectra. Exposure of the NiAl plate to the ambient atmosphere resulted in the formation of an Al₂O₃ layer along with a small amount of NiO. Oxidation of the NiAl plate at 473 K in air formed a film of double‐layered oxide; the top layer consisted of NiAl₂O₄ and a small amount of NiO, and the second layer was Al₂O₃. Successive oxidation at 773 K only changed the oxide‐layer thickness without changing the structure. Formation of oxide observed in the present study corresponds to the thermodynamic prediction for the oxidation behavior of NiAl at 1373 K. Copyright © 2007 John Wiley & Sons, Ltd.     

3d过渡金属在NiAl中的占位及对键合性质的影响

通过赝势平面波方法系统地研究了3d过渡金属元素在B2-NiAl中的占位以及对键合性质的影响.通过形成能得出Sc,Ti,V 和Zn元素优先取代NiAl中的Al位,而Cr,Mn,Fe,Co和Cu优先取代Ni位.通过分析晶格常数变化量、电荷聚居数、交叠聚居数以及价电荷密度分布, 讨论了晶格畸变和键合性质的变化.结果表明: 取代Al的Sc,Ti,V和Zn元素掺杂使NiAl中晶格发生畸变,这对NiAl键合性质的变化起着重要作用,这些掺杂元素与第一近邻Ni原子产生强烈的排斥作用,形成反键,同时它们之间发生较大的电荷转 关键词： NiAl金属间化合物 3d过渡金属 第一性原理 键合性质     

First-principles investigation on ideal strength of B2 NiAl and NiTi alloys

For B2 NiAl and NiTi intermetallic compounds, the ideal stress–strain image is lack from the perspective of elastic constants. We use first-principles calculation to investigate the ideal strength and elastic behavior under the tensile and shear loads. The relation between the ideal strength and elastic constants is found. The uniaxial tension of NiAl and NiTi along <001> crystal direction leads to the change from tetragonal path to orthogonal path, which is driven by the vanishing of the shear constant C(66). The shear failure under {110}{111} shear deformation occurring in process of tension may result in a small ideal tensile strength(~ 2 GPa) for NiTi. The unlikeness in the ideal strength of Ni Al and Ni Ti alloys is discussed based on the charge density difference.     

Alloying-Triggered Phase Engineering of NiFe System via Laser-Assisted Al Incorporation for Full Water Splitting

It is challenging to design one non-noble material with balanced bifunctional performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for commercial sustainability at a low cost since the different electrocatalytic mechanisms are not easily matchable for each other. Herein, a self-standing hybrid system Ni₁₈Fe₁₂Al₇₀, consisting of Ni₂Al₃ and Ni₃Fe phases, was constructed by laser-assisted aluminum (Al) incorporation towards full water splitting. It was found that the incorporation of Al could effectively tune the morphologies, compositions and phases. The results indicate that Ni₁₈Fe₁₂Al₇₀ delivers an extremely low overpotential to trigger both HER (η₁₀₀=188 mV) and OER (η₁₀₀=345 mV) processes and maintains a stable overpotential for 100 h, comparable to state-of-the-art electrocatalysts. The synergistic effect of Ni₂Al₃ and Ni₃Fe alloys on the HER process is confirmed based on theoretical calculation.     

液体和非晶态NiAl3合金结构的从头算分子动力学模拟

应用从头算分子动力学方法模拟了液体以及淬冷形成的NiAl₃合金体系,得到了它们的对相关函数、结构因子、键对分析信息.结果分析表明,在淬冷条件下得到的体系呈现非晶态性质,且非晶态结构类似于液态NiAl₃合金的结构,可以用液体结构近似描述非晶态性质.还进行了电子结构分析,得到液体NiAl₃合金的电子态密度和电荷分布.在液体镍铝合金中,镍为电子受体,部分电子由铝向镍转移,支持了Candy等人的XPS实验结果.镍铝间强烈作用,形成带有弱共价键性质的金属键.镍在合金中相当分散,这能部分解释由淬冷形成的NiAl₃合金制得的骨架镍催化剂活性增强的原因.