纳米微粒作为电池活性材料的前景

介绍了用溶胶凝胶法、微乳法、低热固相反应法制备纳米级电池活性材料——如MnO_2、Ni(OH)_2、Bi—MnO_2、LiCoO_2以及这些纳米材料的充放电性能。数据表明,一般来说这些纳米材料本身的放电容量并不比相应的常规粒径材料好,但若与常规粒径材料混合,则存在一个最佳混合配比,可大大提高其放电容量。因而纳米材料有可能成为有前景的电池活性材料。     

无汞碱锰电池专用EMD

以碳酸锰贫矿为原料,采用悬浮电解法改善固相表面性能,使用高效添加剂去除钼、铁等金属杂质,生产无汞碱性锌锰电池专用电解二氧化锰;产品纯度高、视比重大,吸液量更适合碱性锌锰电池的技术要求。制成的电池内电阻小、大电流连续放电性能优越、高压放电容量提高;电池阴极成型好,能满足碱性锌锰电池生产的工艺要求。     

某高岭土细尾矿酸浸除铁的研究

研究了用草酸漂白除去高岭土细尾矿中高含量的氧化铁。结果表明 ,草酸能够溶解高岭土中的可浸铁 ,当 p H值低于 1.2 ,浸取温度为 80℃ ,用草酸浸取除铁后 ,高岭土细尾矿的白度达80 % ,达到了工业应用的基本要求。     

Highly active OMS-2 for catalytic ozone decomposition under humid conditions

Four kinds of cryptomelane-type octahedral molecular sieve(OMS)-2-X(the X represents the molar ratio of KMnO_4/MnAc_2) were prepared as catalytic materials for ozone decomposition through a one-step hydrothermal reaction of KMnO_4 and MnAc_2, by changing their molar ratios. These samples were characterized by N_2 adsorption–desorption, X-ray di raction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), temperature programmed reduction by H_2(H_2-TPR) and X-ray photoelectron spectroscopy(XPS). Among them, the OMS-2-0.7 sample showed the best O_3 conversion of 92% under high relative humidity(RH) of 90% and gas hourly space velocity of 585,000 h-1. This was accordingly thought as a possible way for purifying ozone-containing waste gases under high RH atmospheres. The e ciency of ozone decomposition of the prepared OMS-2-X sample was found to be related to specific surface area, particle size, surface oxygen vacancies, and Mn~(3+) cation amounts. The one-step hydrothermal synthesis was shown to be a simple method to prepare the considerably active OMS-2 solids for ozone decomposition.     

Phase Diagram of the BaO-CuO Binary System

The phase diagram of the BaO-CuO binary system has been investigated in air and in a mixed gas of Ar + 0.21 atm of O₂. The existence of two compounds, BaCuO₂ and Ba₂CuO₃, was confirmed. The phase transition of Ba₂CuO₃ from an orthorhombic to a tetragonal phase was observed to occur at 1083 K. The lattice constants of the tetragonal Ba₂CuO₃ phase were determined to be a = 1.2975 nm and b = 0.3992 nm. BaCuO₂ was shown to melt incongruently by a synthetic reaction at 1289 K. Furthermore, the existence of two eutectic reactions and a peritectic reaction in the present system was confirmed.     

Transition Metal Oxide Work Functions: The Influence of Cation Oxidation State and Oxygen Vacancies

Transition metal oxides are capable of a wide range of work functions. This quality allows them to be used in many applications that involve charge transfer with adsorbed molecules, for example as heterogeneous catalysts, as charge‐injection layers in organic electronics, and as electrodes in fuel cells. Chemical and structural factors can alter transition‐metal oxide work functions, often making their work functions difficult to control. Little is known about the effects of the cation oxidation state and point defects on the oxide work function. It is necessary to understand how such chemical and structural factors affect work functions in order to controllably tune transition metal oxides for desired applications. Here, a correlation between the oxide work function and cation oxidation state is demonstrated. This correlation is attributed to the change in cation electronegativity with oxidation state. A model is presented that relates the work function to the oxygen deficiency for d⁰ oxides in the limit of dilute oxygen vacancies. It is proposed that the rapid initial decrease in work function, observed for d⁰ oxides, is caused by an increase in the density of donor‐like defect states. It is also shown that oxides tend to have decreased work functions near a metal/metal‐oxide interface as a consequence of the relationship between defects and work function. These insights provide guidelines for tuning transition metal oxide work functions.     

Organic Diamine-Regulated Vanadium Oxides as Cathode Materials for High-Performance Sodium Ion Batteries

Pre-intercalating ions between V O layers is considered to be an effective strategy to modulate the interlayer spacing of 2D vanadium oxides. However, the rigid pre-intercalated ions hardly keep stable during repeated charging/discharging process and their sizes limit the extent of interlayer spacing expansion, which inevitably lead to poor rate capability and cycle stability. In this work, aliphatic diamines are adopted as pre-intercalated guests to elastically modulate the interlayer spacing of V O layers by tuning the chain length of the organic diamine molecules. Benefiting from the strong interaction between the terminal doubly protonated amine and the polar negative oxygen bridge of the V O layers, the aliphatic diamine molecules can act as a structural stabilizer between the layers and boost fast Na ion diffusion (10⁻⁸ to 10⁻¹⁰ cm² s⁻¹). The sodium ion battery based on the first synthesized 1,6-hexanediamine pre-intercalated vanadium oxide supported on nickel foam hybrid cathode achieves a large specific capacity of 597 mAh g⁻¹ at 0.09 A g⁻¹, as well as superior rate performance and cycling stability. This work provides a strategy to elastically modulate 2D layered materials with tunable interlayer spacing for batteries based on large-size-ions.     

Correlation between Interfacial Oxides and Electrical Characteristics of GaN Schottky Diodes

The electrical characteristics of GaN schottky diode with and without the interracial oxides are compared in this paper. The influence of interracial oxides on the electrical characteristics of the schottky diodes has been confirmed by the I-V, C-V measures. We find the barrier height have a reduction of 0.05 eV- 0.1 eV. There is an interracial insulating oxide with the thickness of 0. 05 nm- 0. 1 nm after conventional cleaning. Either the forward or the backward currents increase. The backward punch through voltages are reduced to 50% and the capacitances have increased by 100%.     

Lead‐Free Polycrystalline Ferroelectric Nanowires with Enhanced Curie Temperature

Ferroelectrics are important technological materials with wide‐ranging applications in electronics, communication, health, and energy. While lead‐based ferroelectrics have remained the predominant mainstay of industry for decades, environmentally friendly lead‐free alternatives are limited due to relatively low Curie temperatures (T _C) and/or high cost in many cases. Efforts have been made to enhance T _C through strain engineering, often involving energy‐intensive and expensive fabrication of thin epitaxial films on lattice‐mismatched substrates. Here, a relatively simple and scalable sol–gel synthesis route to fabricate polycrystalline (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ nanowires within porous templates is presented, with an observed enhancement of T _C up to ≈300 °C as compared to ≈90 °C in the bulk. By combining experiments and theoretical calculations, this effect is attributed to the volume reduction in the template‐grown nanowires that modifies the balance between different structural instabilities. The results offer a cost‐effective solution‐based approach for strain‐tuning in a promising lead‐free ferroelectric system, thus widening their current applicability.     

Universal Interface between Functional Oxides and Silicon

Integration of crystalline oxides with silicon provides a versatile platform to extend and advance silicon technology. The interface between oxide and Si controls the structure and functional properties of the resulting material. In particular, the formation of a submonolayer metal phase on silicon is the standard approach to stabilize the epitaxial growth of oxides. However, fundamental questions—a) whether the interface transforms in the process of the synthesis; and b) if it is possible to control the interface and its electronic structure by varying the submonolayer template—remain unanswered. The present study employs MBE synthesis of EuO and SrO on Si(001) to demonstrate that the structure of the oxide/Si interface does not depend on the type of the template, its symmetry, and stoichiometry. Chemical transformations of the templates converging into the same 2D product are detected in situ by electron diffraction. Then, the common interfacial structure of 1D periodicity is visualized by high-resolution electron microscopy. The study provides insights into the process of oxide integration with silicon but also sets the limits in designing oxide/Si interfaces.