锰氧化物的构造、合成及在锂离子二次电池正极材料的应用

锰氧化物通常以各种隧道构造、层状构造的化合物存在。这些锰氧化物作为锂离子二次电池正极材料显示了优越的电化学性质，其电气特性依据锰氧化物结晶构造和合成条件的不同而存在很大的差异。本文对于隧道状及层状锰氧化物的结晶构造、合成及其作为锂离子二次电池正极材料所显示的电气特性等进行了评述。     

庞磁电阻材料的研究进展

20世纪自旋电子学的高速发展以及对强关联电子材料的进一步研究使得具有庞磁电阻效应的稀土掺杂锰氧化物成为凝聚态物理和功能材料研究的重要领域。锰氧化物的载流子自旋极化率高，在居里度附近有很大的磁电阻效应，因此在自旋电子学中有潜在应用前景。锰氧化物是典型的强关联电子材料，它对目前有关强关联体系的认识提出了很大挑战。本文介绍了锰氧化物所具有的包括庞磁电阻效应在内的各种效应及其可能的应用。     

锰氧化物催化分解室内甲醛的研究进展

甲醛是一种常见的室内污染物,一定浓度的甲醛会危害人类的身体健康。因此,甲醛的消除尤为重要。锰氧化物是一种深度氧化剂,催化活性高,在室温下能够较好地催化氧化甲醛,且不会产生二次有害气体,是近几年来催化降解甲醛的研究热点之一。本文对单一锰氧化物、过渡金属掺杂锰氧化物以及负载锰氧化物催化剂进行了介绍,并简述了锰氧化物的晶体、形貌、表面处理对甲醛催化效果的影响,概述了甲醛催化分解机理,并对锰氧化物催化降解甲醛的发展趋势进行了展望。     

一种安全、价廉并可快速充电的车用锂电池

麻省理工学院的科研人员研制出一种新型锂电池，该种新型锂电池用于电动混合动力汽车用电池组更为价廉。作为小型电力设备的动力装置，锂镍锰氧化物电池组比锂钴氧化物电池组更稳定、更安全。麻省理工研制的新型电池采用了比钴更便宜的锰和镍。     

钙钛矿锰氧化物低维纳米结构研究进展

钙钛矿结构锰氧化物由于同时存在电荷、自旋、轨道、晶格等多种自由度, 它们之间很强的相互作用和相互竞争导致了一系列新颖的物理现象, 如庞磁电阻效应、巨磁熵效应、绝缘体-金属转变、电子相分离、电荷/轨道有序等现象, 使其成为凝聚态物理学研究的热点。随着微电子器件日趋集成化和微型化, 其特征尺寸越来越小, 目前基于钙钛矿结构锰氧化物微电子器件的特征尺寸已经进入纳米尺度。在纳米尺度钙钛矿结构锰氧化物具有显著的尺寸效应, 表现出与薄膜及块材不同的电、磁输运特性, 在新一代微电子器件领域具有重要的应用价值。近年来人们在钙钛矿锰氧化物低维纳米结构制备、电磁输运特性测量、微结构表征及理论模拟方面, 都取得了较大的研究进展, 本文对此进行了评述。首先, 概述了钙钛矿锰氧化物低维纳米结构的微结构研究进展; 介绍了钙钛矿锰氧化物低维纳米结构的电子相分离及电荷有序现象; 评述了其电磁输运特性的纳米尺度表征; 讨论了钙钛矿锰氧化物低维纳米结构在自旋电子学、磁随机存储器和传感器方面的应用进展。最后指出了未来钙钛矿锰氧化物低维纳米结构研究需要重点解决的一些问题。     

多孔锰氧化物材料的制备与性能研究进展

孔径从微孔到介孔的多孔锰氧化物材料有多种制备方法.不同的制备方法,材料的性能有所不同.多孔锰氧化物材料在可充锂电池、高级分离技术、化学传感、催化以及环保等领域有潜在的重要应用价值.综述了多孔锰氧化物材料在结构、制备和性能等方面的研究进展.     

无机层状化合物的剥离技术及应用研究

从无机层状化合物构造出发,描述了不同电性无机层状化合物的结构和剥离方法.在此基础上着重介绍了层状锰氧化物的剥离过程,并利用剥离/重组技术成功合成了一系列纳米级锰氧化物功能材料,所合成的纳米级锰氧化物功能材料期待在选择性吸附剂、选择性催化剂及锂离子二次电池正极材料等方面得到广泛应用.     

掺Ag磁性氧化物的庞磁电阻效应

本文重点介绍了掺Ag的钙钛矿锰氧化物和磁铁矿的磁电阻增强效应。结构分析表明，这些材料是由铁磁性的钙钛矿锰氧化物相或亚铁磁性的磁铁矿相与非磁性的金属Ag相所组成的两相复合物。由于金属Ag相的存在，它们的低场磁电阻效应明显增强。这可归因于传导电子在磁性相和非磁性相界面处的自旋相关散射的增强。     

钙钛矿型锰氧化物相分离研究进展

相分离作为一种物理现象,在钙钛矿结构锰氧化物中普遍存在,成为近年来此领域重要的研究课题之一.介绍了相分离的发展历史、分类,总结了相分离在钙钛矿结构锰氧化物中的实验和理论研究进展,并给出了该领域的发展趋势.     

由非晶态分子合金制备纳米稀土复合氧化物La0.67-xNdxSr0.33MnO3

钙钛矿型烯土锰氧化物因其特殊的巨磁电阻效应，引起人们广泛的关注，本文用非晶态分子合金为前驱体，在低温下制备了La0.67-xNdxSr0.33MnO3的系列纳米复合氧化物。通过IR，TG－DTA，XRD，AFM等对合成条件及纳米粒子的组成，结构，形貌，粒径进行了分析。     

Spontaneous oxide reduction in metal stacks

Aluminum and copper interconnects are widely used for microelectronic applications. A problem can arise when interfacial oxides are present. Such oxides can significantly degrade device performance by increasing electrical resistance. This paper describes analyses of interfacial oxide layers found in Al/Ta and Ta/Cu metal stacks. The analyses were performed through transmission electron microscopy (TEM). The data indicated that the interfacial oxides resulted from spontaneous reductions; that is, Al spontaneously reduced Ta₂O₅ to form Al₂O₃, while Ta spontaneously reduced Cu oxide to form Ta₂O₅.     

Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co₃O₄, NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm² current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides.     

Route to transition metal carbide nanoparticles through cyanamide and metal oxides

We have designed an efficient route to the synthesis of transition metal carbide nanoparticles starting from an organic reagent cyanamide and transition metal oxides. Four technologically important metal carbide nanoparticles such as tungsten carbide, niobium carbide, tantalum carbide and vanadium carbide were synthesized successfully at moderate temperatures. It is found that cyanamide is an efficient carburization reagent and that the metal oxides are completely transmitted into the corresponding carbide nanoparticles. A possible mechanism is proposed to explain the results of the reaction between cyanamide and the metal oxides.     

纳米润滑材料应用研究进展

阐述了纳米无机单质,无机盐、氢氧化物、氧化物和高分子微球的摩擦学研究进展,综述了纳米粒子在基础油中的分散方法及抗磨减摩机理,介绍了纳米粒子作为润滑油添加剂的应用现状。     

Crystallization of amorphous complex oxides: New geometries and new compositions via solid phase epitaxy

The crystallization of amorphous complex oxides via solid phase epitaxy enables a wide range of opportunities in the formation of oxide materials in new geometries and with previously inaccessible compositions. Emerging methods for controlling crystallization from the amorphous form arise from recent advances in the deposition of amorphous oxides, the formation and placement of crystalline seeds, and have built on an expanded understanding of the kinetics of nucleation and crystal growth. Key discoveries include methods for the creation of epitaxial layers in perovskite, spinel, and pyrochlore complex oxides. The creation of nanoscale homoepitaxial and heteroepitaxial seeds has the potential to enable new directions in the integration of complex oxides with semiconductors and in devices based on oxygen ion transport. Future opportunities include the creation of complex oxides in morphologies and compositions exhibiting electronic, thermal, and magnetic phenomena enabling a variety of applications.     

Porous manganese oxide synthesized through organic-electrolyte templates and their catalytic applications

We report a facile approach to the preparation of porous manganese oxide materials by the organic-electrolyte templates based on strategy. The final products are thoroughly characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and Brunauer–Emmett–Teller (BET) techniques. The results reveal that porosity (pore size and distribution, surface area) of these manganese oxides has strong relationship with the templates used, which implies a simple way to obtain a series of porous materials. By comparing the catalytic effects of these manganese oxides in oxidation of indene and benzyl alcohol, we find that the pore size and distribution are also crucial to the catalytic properties of these porous materials.     

Pyrochlore type semiconducting ceramic oxides in Ca-Ce-Ti-M-O system (M = Nb or Ta)—Structure, microstructure and electrical properties

A new series of pyrochlore type ceramic semiconducting oxides in Ca-Ce-Ti-M-O (M = Nb or Ta) system has been synthesized by the conventional ceramic route. The electrical conductivity measurements show that these oxides exhibit semiconducting behavior and the conductivity increases with the Ce content in the compound. Activation energy of the current carriers is in the range of 0.5-1.6 eV. The electrical conductivity in these oxides is due to the presence of Ce³⁺, which remains in the reduced state without being oxidized to Ce⁴⁺ by structural stabilization. The photoluminescence and X-ray photoelectron spectroscopy analysis corroborate the presence of Ce in the 3+ state. Impedance spectral analysis is carried out to evaluate the transport properties and indicates that the conduction in these compounds is mainly due to electronic contribution. The X-ray powder diffraction and Raman spectroscopy analysis establishes that these oxides belong to a cubic pyrochlore type structure.     

Acidity and basicity of hydrotalcite derived mixed Mg-Al oxides studied by test reaction of MBOH conversion and temperature programmed desorption of NH3 and CO2

Mg-Al hydrotalcites intercalated with five different interlayer anions—CO₃²⁻, SO₄²⁻, Cl⁻, HPO₄²⁻ or terephthalate—were synthesized by either the coprecipitation or ion-exchange method. The structure of the as-synthesized samples and the presence of intended anions in the interlayer gallery of hydrotalcites were determined by X-ray diffraction and FTIR spectroscopy. On calcination at 600 °C the materials were transformed into mixed metal oxides. The kind of the counterbalancing anions present in the parent hydrotalcite influences strongly textural parameters of the obtained Mg-Al oxides. Both temperature-programmed desorption of NH₃ and CO₂, and test reaction of 2-methyl-3-butyn-2-ol (MBOH) conversion were used to determine the acidity and basicity of the samples. The hydrotalcite derived mixed Mg-Al oxides showed the presence of Brønsted and Lewis acid and base sites. However, the strong basic character of the solids caused that acetone and acetylene were observed as the major products of MBOH conversion.     

电子束辐照诱导Cu超微粒子发生反应的HREM研究

用高分辨电子显微镜中的电子束对Ｃｕ超微粒子进行了连续的照射和跟踪观察，结果表明，电子束的辐照，首先使Ｃｕ发生了氧化反应，反应途径：Ｃｕ＋Ｏ２→成分为Ｃｕ和Ｏ的非晶膜→Ｃｕ的晶体氧化物：接着，新生的Ｃｕ的晶体氧化物，在电子束的继续照射下，又发生还原反应，Ｃｕ的氧化物不断地还原为Ｃｕ。在整个还原反应中，伴随着样品局部的多重又氧化还原现象交替出现。     

Synthesis and characterization of IR up-conversion material CaS:Eu, Sm by low-temperature combustion synthesis method

Infrared up-conversion material CaS:Eu, Sm was synthesized by the low-temperature combustion synthesis (LCS) method, which has expanded the application range of the LCS method which is always used in the synthesis of oxides and compound oxides. The combustion process was discussed and the effect of the amount of carbamide on the up-conversion luminescence properties was analyzed. XRD patterns show that the products are with the cubic CaS crystal structure. Spectral analysis indicates that the sample can be excited effectively by ultraviolet or visible light to store energy, and subsequently is sensitive to 800-1600 nm infrared light and then emit red light resulting from the multi-transitions of Eu²⁺ 4f⁶5d → 4f⁷(⁸S_7/2).