(NH4)2V7O16 Microbricks as a Novel Anode for Aqueous Lithium-Ion Battery with Good Cyclability

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH₄)₂V₇O₁₆ with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li⁺/Na⁺ hybrid ion batteries. The two novel full cell systems (NH₄)₂V₇O₁₆||Li₂SO₄||LiMn₂O₄ and (NH₄)₂V₇O₁₆||Na₂SO₄||LiMn₂O₄ both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g⁻¹ was demonstrated in the (NH₄)₂V₇O₁₆||Li₂SO₄||LiMn₂O₄ system, whereas no capacity attenuation is observed in the (NH₄)₂V₇O₁₆||Na₂SO₄||LiMn₂O₄ system. The reaction mechanisms of the (NH₄)₂V₇O₁₆ electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH₄)₂V₇O₁₆ can be a promising anode material for aqueous rechargeable lithium-ion batteries.     

Synthetic beta‐K0.33V2O5 Nanorods: A Metal–Insulator Transition in Vanadium Oxide Bronze

We found a linear relationship between the metal–insulator transition (MIT) temperature and the A⁺ ionic radius of the beta‐A_0.33V₂O₅ bronze family, leading our attention to beta‐K_0.33V₂O₅ which has been neglected for a long time. We have introduced a facile hydrothermal method to obtain the single‐crystalline beta‐K_0.33V₂O₅ nanorods. As expected, both the temperature‐dependence of the resistivity and magnetization demonstrated MITs at about 72 K for beta‐K_0.33V₂O₅, thus matching well with the linear relationship described above. The beta‐K_0.33V₂O₅ was assigned as a new member of the beta‐A_0.33V₂O₅ bronze family for their similar crystal and electronic structures and their MIT property; this addition enriches the beta‐A_0.33V₂O₅ bronze family.     

A Novel Cathode Material for Cathodic Dehalogenation of 1,1‐Dibromo Cyclopropane Derivatives

Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives.     

Design of experiment for evaluation of uncertainty from sampling in the framework of the fitness for purpose concept: a case study

The design of an experiment for the evaluation of sampling uncertainty in the framework of the fitness for purpose concept is described in terms of probabilities (risks of the user) of type 1 and type 2 errors in decisions concerning the significance of effects influencing the sampling uncertainty and the measurement results. As a case study, an experiment based on the duplicate method for quantification of the sampling uncertainty and inhomogeneity (heterogeneity) of a melt of tin-free bronze produced in a 10-ton reflective oven is analyzed. The melt is defined as the sampling target. It is shown that the number of such targets (melts), the number of samples under analysis and the number of replicate analyses can be minimized, i.e., the size and cost of the experiment can be reduced, if the user knows which risks are acceptable. When inhomogeneity of the sampling target has a systematic character, like the decrease of the mass fraction of aluminum from the beginning to the end of the melt pouring in the case study, the inhomogeneity effect can be separated from the sampling uncertainty and evaluated according to the user’s needs.     

Electrochemical properties of systems with rubidium-tungsten-oxide bronze

Single-phase rubidium-tungsten-oxide bronze of the composition Rb_0.3WO₃ with hexagonal syngony (a = 0.7387 ± 0.0004 nm, c = 0.7547 ± 0.0004 nm) is synthesized. The ionic constituent of the bronze conductivity, determined for the first time ever, is nearly three orders of magnitude as small as the electronic constituent and varies from 1.1 × 10^?2 to 2.7 × 10^?2 S cm^?1 at 30–84°C. The reversibility of the Rb_0.3WO₃/Rb₆La₂Si₆O₁₈ interface increases with the environment humidity. The exchange current is equal to 6.4 × 10^?4 A cm^?2 at a temperature of 30°C and a relative humidity of 58%. It is shown that the synthesized bronze may, in principle, be utilized in the role of a reference electrode in solid-state potentiometric sensors for carbon dioxide and hydrogen sulfide that would be capable of operating in natural conditions.     

铝青铜合金的基本特性与摩擦学性能的关系

利用扫描电子显微镜和Ｘ射线衍射仪等对多种铝青铜合金的微观组织、微区成分、磨损表面形貌和磨屑等进行了观察与分析，研究了合金的基本特性与摩擦学性能的关系，探讨了边界润滑条件下铝青铜合金与４５＃钢对摩时的磨损机制．结果表明，铝青铜合金中软相与硬相的含量比和α－相的晶粒尺寸对合金的微观磨损形式和磨损机制都有重要影响：当较软的α－相与较硬的β－相＋Ｋ－相之和的相对含量比约为７０３０，α－相的晶粒尺寸在３２～６０μｍ之间时，铝青铜合金的摩擦学性能优良，主要磨损形式是轻度的粘着磨损、磨粒磨损和疲劳磨损；当软硬相的含量比更高或更低，且α－相的晶粒尺寸更大或更小时，铝青铜合金的主要磨损形式分别为严重的粘着磨损和疲劳磨损，或严重的磨粒磨损和疲劳磨损     

青铜表面GPTS/MTMS复合防蚀涂层的成分分析

利用缓蚀剂BTA及NBS等助剂改性的GPTS/MTMS复合材料,在青铜表面制成透明防蚀涂层,用XPS分析了涂层组成。结果表明,涂层主要由C、Si、O、N以及Cu元素组成,改性前后C、Si、O、N元素的价态不变,Cu元素以Cu2 形式存在,其含量在改性后有明显增加。     

The Superstructure of Lead Tetragonal Tungsten Bronze

Electron-optical studies of the superstructure of lead tetragonal tungsten bronze (lead-TTB) are presented. Samples were synthesized for a range of lead compositions and synthesis conditions. For lead-TTB synthesized for very short reaction times, compositional analysis combined with electron diffraction revealed these specimens to also contain significant levels of an intergrowth tungsten bronze (ITB) phase. It was proposed that ITB was formed during the reaction as an intermediate between the tungsten oxide reagent and lead-TTB. Electron-diffraction investigations of lead-TTB over a range of specimen compositions determined that the large majority of crystallites examined exhibited a well-ordered 2√2a_TTB×√2b_TTB×2c_TTB supercell periodicity, although evidence of a larger a-axis repeat was also observed. No evidence for a variation in the supercell with lead composition was observed. A model for the supercell was generated from consideration of stacking sequences of correlated ordered arrays of lead and tilted octahedra and it was demonstrated that larger superstructures could be generated using alternative stacking sequences.     

Microstructure, microhardness and dry friction behavior of cold-sprayed tin bronze coatings

In this paper, two types of tin bronze coatings (Cu-6 wt.% Sn and Cu-8 wt.% Sn) were prepared by cold spray process. The as-sprayed coatings were subjected to a vacuum heat treatment at 600 °C for 3 h. The coating microstructure, microhardness and tribological performance were characterized. The effects of the tin content and the vacuum heat treatment on the microstructure, microhardness and tribological behavior of the coatings were investigated. It is found that the as-sprayed CuSn6 (As6) and CuSn8 (As8) coatings exhibit practically an identical porosity. Meanwhile, As8 presents a higher microhardness than As6. In addition, the increase of the tin content in the powder feedstock leads to a lower wear rate. After a heat treatment, coating porosities are significantly reduced. However, the coating hardness is significantly decreased and the coating presents a much decreased wear resistance. For the as-sprayed coatings, such factors as ploughing and particle delamination could determine the sliding process. The heat treatment results in a distinct modification of the tribological behavior. For the annealed coatings, the adhesion, between the coating and the counterpart, could play a dominant role in the sliding process.