钙钛矿型La1-xSrxMnO3纳米薄膜的制备及其光催化性能

采用溶胶-凝胶法和浸渍提拉技术在载玻片基底上制备出钙钛矿型La1-xSrxMnO3纳米薄膜;采用TG/DTA技术分析前驱体凝胶的热分解历程;利用AFM观察薄膜的形貌特征;通过XRD进行物相分析,并计算其晶粒尺寸。结果表明,La1-xSrxMnO3薄膜在600℃形成,为钙钛矿结构,其平均晶粒尺寸为10.349nm。采用该薄膜对多种水溶性染料进行光催化降解试验的结果表明,掺杂后该类纳米薄膜有较好的光催化效果,当x=0.2时光催化效果最好。     

CrSiN纳米复合薄膜的摩擦学性能

采用中频非平衡反应磁控溅射技术在单晶硅P(111)基材上制备了CrSiN纳米复合薄膜。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、Kevex能谱仪(EDX)、高分辨率透射电子显微镜(HRTEM)和纳米压痕仪对薄膜的相结构、化学成分组成和力学性能进行了测试分析。利用球-盘式摩擦磨损试验机(UMT-2)考察了薄膜和GCr15钢球对磨的摩擦学性能并采用扫描电镜(SEM)观察磨痕形貌。结果表明:CrN薄膜中Si元素的掺杂改变了薄膜晶体结构,所制备的CrSiN复合薄膜为多相复合结构,即nc-CrN/aSi3N4所组成的纳米晶/非晶复合结构。CrSiN纳米复合薄膜的力学性能均优于CrN薄膜,其硬度均高于CrN薄膜的硬度,其中Si原子数分数为12.6%时薄膜的硬度达到最大,对应纳米晶/非晶复合强化。CrSiN纳米复合薄膜的摩擦因数低于CrN薄膜,具有很好的抗磨损性能,并具有一定的润滑作用。     

纳米超薄膜传感器研究进展

就纳米超薄膜制备方法的进展进行了详细的介绍,并对超薄膜在传感器方面的应用,包括化学传感器、生物传感器、磁性传感器以及光学传感器进行了探讨.     

金银纳米粒子-稀土氧化物复合薄膜的光吸收特性

在真空中用蒸发沉积的方法制备了埋藏有Ag或Au纳米粒子的稀土氧化物复合薄膜：Ag—La2O3、Ag—Nd2O3、Ag-Sm2O3、Au—La2O3、Au—Nd2O3和Au—Sm2O3。通过光吸收实验研究，发现这些薄膜都在光波长310-1200nm内出现吸收峰，Ag纳米粒子—稀土氧化物薄膜和Au—Sm2O3薄膜的光吸收峰位置随Ag或Au粒子粒径和数量的增加产生红移；而Au—La2O3和Au-Nd2O3薄膜的光吸收随Au量的增大变为金属性光吸收。分析表明，Ag或Au粒子与稀土氧化物之间的相互作用是影响光吸收峰位置的主要原因。     

稀土钙钛矿型复合氧化物在汽车尾气催化转化器中的作用

介绍了汽车尾气催化转化器的组成、工作原理和类型。根据国内外有关报道,综述了稀土钙钛矿型复合氧化物在汽车尾气催化转化器中的作用：既改善了储氧功能,又增加了催化活性和催化剂中涂层料的热稳定性等。作者从技术和理论的角度说明稀土元素在汽车尾气催化转化器中作用;尤其在催化净化器中,CeO2在助催化和稳定化方面赶到了十分明显的作用。随着汽车工业的快速发展,稀土氧化物在汽车尾气催化转化器中的运用前景看好。     

Ti-Si-N纳米复合薄膜的制备及其力学性能

采用离子束溅射与磁过滤阴极弧共沉积技术在单晶硅片(400)表面制备Si含量(摩尔分数)为3.2%~15.5%范围内的TiSiN薄膜。采用X射线光电子能谱(XPS)、电子散射谱(EDS)、X射线衍射仪(XRD)研究TiSiN薄膜的显微结构和力学性能。结果表明:低Si含量的薄膜以面心立方晶型的Ti(Si)N固溶体形式存在,择优晶面为(200)面;当Si含量饱和后,出现Ti(Si)N和Si3N4非晶相,形成Ti(Si)N/Si3N4纳米复合结构。薄膜硬度范围在22~26GPa,采用Si3N4小球为对偶时薄膜的摩擦因数均维持在0.13~0.17之间。Si含量为10.9%时,硬度达最大值,结合较低的粗糙度,使其摩擦因数和磨损率达到最低值。     

纳米金刚石薄膜的制备和应用

纳米金刚石薄膜的优异性能吸引了众多学者的关注,同时也成为CVD金刚石薄膜研究领域的新热点。文章对国内外的纳米金刚石膜制备的研究状况做了详细介绍,并对纳米金刚石薄膜的应用进行了讨论。     

纳米金刚石薄膜研究进展

本文对纳米金刚石薄膜的研究现状和发展趋势进行了综合评述，从纳米金刚石薄膜的沉积原理和工艺以及纳米效应表征等方面分析了国内外最新研究成果，比较了常规和纳米金刚石薄膜不同沉积工艺和形核生长机理，对纳米金刚石薄膜的硬度、内应力、摩擦特性等机械性能也作了概述，在此基础上，提出在常规金刚石薄膜基础上沉积纳米金刚石薄膜组成复合涂层的新方法。     

纳米氧化物粉体的制备

综合介绍了近十年来纳米氧化物粉体的各种制备方法及其适用性。     

纳米金刚石薄膜的应用及其研究进展

以纳米金刚石薄膜的应用为主线,讨论了它在机械、光学、声学、电学等应用领域的优势,以实例分析、证明了其在各领域中所展现出的优异性能。综述了纳米金刚石薄膜在上述应用领域的研究进展,同时从不同方向阐释了其研究应用过程中所存在的不足,并对其今后的主要发展方向进行了展望。     

Interface and surface effects on ferroelectric nano-thin films

The effects originating from the interface or surface of a ferroelectric nano-thin film are accounted for in the phase field model devised. Two-dimensional simulations of domain structures and hysteresis loops were carried out. The simulation results show that transformation from an irregularly spaced to a regularly spaced 180° stripe domain structure occurs owing to competition and cooperation of the elastic and depolarizing energy in ferroelectric nano-thin films. This result is in agreement with recent experimental observations. The remnant polarization was found to decrease with decreasing film thickness, and the “actual” hysteresis loop, which was first studied by Bratkovsky and Levanyuk [Bratkovsky AM, Levanyuk AP. Appl Phys Lett 2006;89:253108.], was plotted to characterize the domain structures of ferroelectric nano-thin films and the imperfect screening effects of the electrodes.     

Symmetry analysis of complex oxides of transition metals

Some specific properties of antiferromagnetically ordered crystals, such as the antiferromagnetic photovoltaic effect, interaction of spin waves with polar optical phonons, and the effect of this interaction on the structural phase transitions and magnetic transitions into incommensurate structures, have been considered based on the group-theoretical approach.     

Epitaxial thin films of isotropic conductive oxides for devices

Oxide materials posses an enormous range of electrical, optical, and magnetic properties and, thus, have great potential for novel device applications. Epitaxial metallic oxide layers should yield the best device performance because of their excellent chemical and structural compatibility with many oxide materials.     

Low-temperature perovskite-type cadmium titanate thin films derived from a simple particulate sol–gel process

Low-temperature perovskite-type cadmium titanate (CdTiO₃) with a nanocrystalline and mesoporous structure was prepared at various Ti:Cd molar ratios by a straightforward particulate sol–gel route. The prepared sols had a narrow particle size distribution, in the range 23–26 nm. X-ray diffraction and Fourier transform infrared spectroscopy revealed that the powders contained a mixture of ilmenite-CdTiO₃, perovskite-CdTiO₃, anatase and rutile phases, depending on the annealing temperature and the Ti:Cd molar ratio. Perovskite-CdTiO₃ was the major type obtained from cadmium-prominent powders at low temperature, whereas ilmenite-CdTiO₃ was the major type obtained from titanium-prominent powders at high temperature. It was observed that the anatase-to-rutile phase transformation accelerated with decreasing Ti:Cd molar ratio. Furthermore, the ilmenite-to-perovskite phase transformation accelerated with a decrease in both the Ti:Cd molar ratio and the annealing temperature. The crystallite sizes of the ilmenite- and perovskite-CdTiO₃ phases reduced with increasing the Ti:Cd molar ratio. Field emission scanning electron microscopic analysis revealed that the average grain size of the thin films decreased with an increase in the Ti:Cd molar ratio. Moreover, atomic force microscope images showed that CdTiO₃ thin films had a columnar-like morphology. Based on Brunauer–Emmett–Taylor analysis, cadmium titanate powder containing Ti:Cd = 75:25 showed the greatest surface area and roughness and the smallest pore size among all the powders annealed at 500 °C. This is one of the smallest crystallite sizes and largest surface areas reported in the literature, and can be used in many applications in areas from optical electronics to gas sensors.     

Progress in oxygen behaviors in two-dimensional thin films

With the development of spintronics,the investigation on the behavior of oxygen in two-dimensional materials has never ceased.On account of its lively nature,oxygen is hard to exist alone in the system.However,it will interact with other atoms and produce complex orbital hybridization effect,which has influenced the performance of the material.Especially for materials in nanoscale,it is inevitable to introduce the oxygen atoms,no matter what in the process of preparation or employ.Therefore,it is necessary to carry on the research about the effect of oxygen behaviors in the two-dimensional thin films.In this paper,it will mainly introduce the effect of oxygen behaviors on the magnetic properties,electrical properties,phase transition,spin-dependent properties and thermal stability,summarize several factors which influence the oxygen behaviors,and generalize the research progress of the mechanism behind the oxygen behaviors.     

Stability of protective oxide films in waste incineration environment—solubility measurement of oxides in molten chlorides

Solubility measurements of several oxides in molten NaCl-KCl and NaCl-KCl-Na₂SO₄-K₂SO₄ were conducted in three different levels of basicity. The dissolution behavior of the oxides showed almost the same tendency as that shown by the dissolution behavior of the oxides in molten Na₂SO₄ in literature. In a waste incineration environment, a protective Cr₂O₃ film easily dissolves in molten chlorides as CrO₄²⁻ because pO²⁻ of the molten chlorides tends to have a small value due to the effect of water vapor contained in the combustion gas. From the result of the solubility measurement, the addition of molybdenum and/or silicon was expected to improve the corrosion resistance of alloys. Laboratory corrosion tests confirmed this expectation. However, the scale analysis suggested that the effect of molybdenum could not be explained completely by only the mechanism derived from the result of the solubility measurement.     

Synthesis of NaxCo2O4 thermoelectric oxides by the polymerized complex method

The thermoelectric oxide Na_xCo₂O₄ was synthesized by the polymerized complex method, which provided a flaky powder. The sintered sample showed a high density, a fine microstructure and improved thermoelectric performance compared to a sample prepared by the conventional solid state reaction method.     

溶胶-凝胶法制备钙钛矿型纳米钛酸锶

以硝酸锶和钛酸丁酯为原料,采用溶胶-凝胶法制备了钙钛矿型纳米SrTiO3.采用红外光谱、差热分析、X射线衍射、扫描电镜及紫外吸收等测试手段,研究了影响溶胶-凝胶过程的诸因素,对制备的SrTiO3粉体的结构和性质进行了表征.结果表明:乙醇、冰醋酸、水、丙三醇、温度及pH值均对溶胶-凝胶过程有明显影响,其中反应温度对胶体形成时间长短和胶体质量影响最明显.钙钛矿型SrTiO3晶体于650时生成,随着热处理温度的升高,粉体的物相组成将发生变化,粉体的尺寸也有所增加,相应的紫外吸收峰也出现红移现象.     

Thermal and mechanical properties of perovskite-type barium hafnate

Polycrystalline samples of the barium perovskite-type oxide, BaHfO₃ were prepared by solid-state reactions from HfO₂ and BaCO₃ powders. The thermal expansion coefficient, heat capacity, thermal diffusivity, thermal conductivity, elastic modulus, Debye temperature, and micro-Vickers hardness were measured. The crystal structure of BaHfO₃ is of the cubic perovskite type with the lattice parameter 0.4171 nm at room temperature. The sample bulk density is 91% of the theoretical density. The average linear thermal expansion coefficient is 6.93 × 10⁻⁶ K⁻¹ in the temperature range between 300 and 1500 K. The Young's modulus equals 194 GPa. The thermal conductivity at room temperature is 10.4 Wm⁻¹K⁻¹.     

Thermal and electrical properties of perovskite-type strontium molybdate

Polycrystalline samples of perovskite-type strontium molybdate, SrMoO₃, have been prepared and the thermal and electrical properties have been measured from room temperature to about 1000 K. The electrical resistivity is of an order of magnitude of 10⁻⁵ to 10⁻⁶ (Ω m) in the whole temperature range. The Seebeck coefficient is around 4–9 μV K⁻¹. At room temperature, the thermal conductivity is about 30 W m⁻¹ K⁻¹, and it decreases with increasing temperature.