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1.
BaTiO_3纳米晶的制备和结构方佑龄,赵文宽,邹化民,王仁卉(武汉大学化学系,武汉大学物理系,武汉,430072)关键词钛酸钡纳米晶,过氧化物,制备,结构BaTiO3具有高介电常数及优异的铁电、压电性能,是一种重要的电子陶瓷材料,因此,对其纳米晶的?..  相似文献   

2.
磁性Fe3O4纳米晶由于其独特的磁性能,已在许多领域得到了广泛的应用,并且在不同的应用领域其制备方法也不尽相同。本文综述了近年来磁性Fe3O4纳米晶的液相制备方法,如沉淀法、溶剂热法、溶胶-凝胶法、微乳液法、微波超声法等研究进展,对这些制备方法的特点进行了归纳概括,并详细分析了制备工艺中不同影响因素对Fe3O4纳米晶结构与性能的影响。同时,对磁性Fe3O4纳米晶在磁流体、微波吸收、污水处理、催化、药物载体、生物酶固定、生物传感器等方面的应用及发展趋势进行了评述,以期对Fe3O4纳米晶的制备及应用有较全面的认识。  相似文献   

3.
综述了尖晶石型铁酸盐纳米晶制备技术的研究进展,介绍了高能球磨法、聚合物热解法、自蔓延燃烧合成法、共沉淀法、水热法、溶胶-凝胶法、微乳液法等典型制备技术的作用原理和技术特点,并对尖晶石型铁酸盐纳米晶制备技术的发展趋势进行了展望。  相似文献   

4.
纳米TiO_2-ZnO二元负载木材的制备及性质   总被引:1,自引:0,他引:1  
采用两步法将TiO_2/ZnO纳米材料与杨木试样复合,制备了纳米二元负载木材.通过X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)和扫描电子显微镜(SEM)对样品的结构和形貌进行了表征,并探讨了不同处理条件下得到的纳米氧化物负载木材及非纳米氧化物负载木材的抗菌性和耐候性.结果表明,氧化锌和二氧化钛二元协同负载木材的抗菌性和耐候性均优于单一纳米晶处理的木材;在溶剂热反应中以正己烷作为溶剂所制备样品的性能优于以水和无水乙醇为溶剂制备的样品;并且纳米结构负载木材的抗菌性和耐候性优于非纳米结构负载的木材.  相似文献   

5.
稀土氯氧化物作为一种重要的发光基质,具有较高的光吸收效率和传能效率,在彩色显示、催化、生物医药、光电转换、气敏等领域均有广泛的应用,已成为光功能材料领域的研究热点之一。目前研究者已用固相法、沉淀法、液相-高温焙烧法、水热与溶剂热法、前驱体热解法、溶胶-凝胶法、静电纺丝法等方法成功地制备了稀土氯氧化物微米颗粒,纳米颗粒、纳米条、纳米片、纳米棒、纳米针、纳米纤维、纳米带、纳米管等稀土氯氧化物微纳米材料。总结了各种制备方法的研究进展及优缺点,并结合本课题组在稀土氯氧化物纳米材料方面的研究工作,对稀土氯氧化物微纳米材料的制备方法的发展方向进行了展望。  相似文献   

6.
本文对钙钛矿型氧化物的制备方法及其用于固体氧化物燃料电池(SOCFs)和金属-空气电池中的最新进展进行了较为全面的综述。制备钙钛矿型氧化物的方法有很多,包括盐分解法、固相法、共沉淀法、溶胶-凝胶法、水热法、反微乳法和模板法等。不同的制备方法可以得到各种形貌的钙钛矿型氧化物,如纳米立方体、纳米管、纳米棒、纳米片、纳米纤维和介孔结构。本文总结了这些制备方法的优点、缺点以及其适用的范围。作为一种重要的功能材料,钙钛矿型氧化物广泛应用于电极材料中。在SOCF中,重点介绍了阴极、阳极和电解质的研究现状,从电极材料的设计出发,比较了它们用于不同电极材料时的稳定性、电导率以及电催化活性,指出不足之处;在空气电极中,主要讨论了影响钙钛矿型氧化物氧的析出/还原催化活性和稳定性的因素。最后对钙钛矿型氧化物今后研究的方向和应用前景进行了预测。  相似文献   

7.
纳米Cr2O3的制备、表征及催化性能   总被引:15,自引:0,他引:15       下载免费PDF全文
首次采用溶胶-凝胶法与共沸蒸馏法耦合技术制备了纳米Cr2O3粉体,并运用BET、TEM、XRD、FT-IR、XPS及H2-TPR对其进行表征,同时采用CO2氧化乙烷脱氢制乙烯反应作为探针反应,考察了纳米Cr2O3的催化性能。首次发现纳米ErgO3的FT-IR谱出现了蓝移现象,并且630cm^-1附近的伸缩振动峰强度增强。初步探讨了纳米氧化物的IR蓝移和红移的原因,指出晶型是影响纳米氧化物红外光谱特征的重要因素。实验结果表明纳米Cr2O3上乙烷和CO2转化率均明显高于常规Cr2O3催化剂;在700℃下,乙烷转化率高达77.1%,而乙烯产率达到了58.98%。  相似文献   

8.
以高岭土为原料,采用水热晶化法,制得了主晶相为莫来石的复合纳米晶。利用XRD、 TEM、 BET及TG~TDA对在不同条件下制得的纳米晶物相、粒度及热稳定性进行了表征。对复合纳米晶进行了CO、 SO2程序升温脱附性能测试。对负载Ni、 Mn、 Co进行程序升温还原测试。结果表明:在脱附物中检测出CO2与固体硫,证明吸附质在纳米晶表面发生了反应。微米晶与纳米晶负载Ni、 Co、 Mn后,随着粒度的不同,负载上的氧化物与载体的相互作用力不同,而表现出不同的峰温与峰面积,表明负载上Ni、 Co、 Mn的氧化物与载体有结构效应,且随晶体表面结构的不同,而表现出不同的H2消耗量。  相似文献   

9.
综述近年来自钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术领域的研究进展,重点介绍熔盐法、有机配合物前驱法、模板法、微乳液法、水热法、溶剂热法和微乳液.溶剂热法的原理和技术特点,比较各种方法的异同点,并提出白钨矿型钨酸盐和钼酸盐纳米晶/微晶制备技术的发展趋势.  相似文献   

10.
采用有机金属液相法,在较低温度下制备了高质量的荧光CdS纳米晶.TEM、UV-Vis、PL及XRD等研究表明,表面活性剂的浓度、反应时间及反应物配比等对所制备的CdS纳米晶的形貌与尺寸、光谱性能及结晶性能等具有显著的影响.控制合适的反应条件,可以获得单分散、光谱性能优异且结晶性好的CdS纳米晶.  相似文献   

11.
The principal methods used to measure ozone concentration are reviewed and experimental comparisons made between chemical methods, with both phosphate and boric acid buffers, UV absorption, and electrochemical methods. The advantages and disadvantages of the methods are considered and recommendations are made for the adoption of a standard reference method for rubber test methods.  相似文献   

12.
Binding parameters of metal complexes with albumins and DNA since the middle of 1990s are considered and summarized. The most widespread spectroscopic methods of estimation of binding parameters are discussed – direct fluorescent methods, indirect fluorescent methods (by fluorescence quenching parameters), and ways of estimation of binding constants by other optical spectroscopic methods. The methods and approaches to calculations used for the determination of binding constants are discussed. The data on the already found binding constants and kinetic parameters is systematized.  相似文献   

13.
The state-of-the-art immunochemical methods for the determination of mycotoxins are considered. Both instrumental (enzyme-linked immunosorbent assay, polarization fluoroimmunoassay, and sensor devices) and noninstrumental methods are presented. The principles of particular methods are considered, and the examples of the use of these methods for the determination of mycotoxins from various groups in food products and animal feeds are given; the main lines of development are discussed.  相似文献   

14.
A review of the well-established and novel analytical methods in mass spectrometry and chromatography-mass spectrometry is presented. General information about the methods is given and their distribution over the fields of analysis and mass spectrometric methods is considered. The classification and validation (certification) of the methods is discussed and their necessary characteristics are specified. The identification criteria contained in the methods and isotope dilution method providing the most precise and accurate results of quantitative analysis are considered. Various characteristics of errors (uncertainty) used in analytical methods are presented.  相似文献   

15.
Thermoanalytical (TA) methods are relatively seldom applied for assessing the physical and chemical proeprties of thin films, but they can be used in studies of composition, phase transitions and film—substrate interactions. In the present paper the possibilities of TA methods in thin film studies are reviewed. The thermoanalytical methods considered are the classical TG and DTA/DSC methods but some complementary methods will also be briefly mentioned. The main emphasis is given to true thin films. Details of sample preparation are also given. An important application of TA methods is characterization of precursors for the CVD growth of thin films, and this is also discussed.  相似文献   

16.
The density functional theory (DFT) is the most popular method for evaluating bond dis-sociation enthalpies (BDEs) of most molecules. Thus, we are committed to looking for alternative methods that can balance the computational cost and higher precision to the best for large systems. The performance of DFT, double-hybrid DFT, and high-level com-posite methods are examined. The tested sets contain monocyclic and polycyclic aromatic molecules, branched hydrocarbons, small inorganic molecules, etc. The results show that the mPW2PLYP and G4MP2 methods achieve reasonable agreement with the benchmark values for most tested molecules, and the mean absolute deviations are 2.43 and 1.96 kcal/mol after excluding the BDEs of branched hydrocarbons. We recommend the G4MP2 is the most appropriate method for small systems (atoms number ≤20); the double-hybrid DFT methods are advised for large aromatic molecules in medium size (20 ≤atoms number ≤50), and the double-hybrid DFT methods with empirical dispersion correction are recommended for long-chain and branched hydrocarbons in the same size scope; the DFT methods are advised to apply for large systems (atoms number ≥50), and the M06-2X and B3P86 methods are also favorable. Moreover, the di erences of optimized geometry of different methods are discussed and the effects of basis sets for various methods are investigated.  相似文献   

17.
The reported data on determining substances by chemical test methods are summarized. The reagents used; methods of their immobilization on supports; and principles, devices, and methods for determining components are considered. The main analytical characteristics are discussed.  相似文献   

18.
橡胶贮存寿命预测方法研究进展与思考建议   总被引:5,自引:0,他引:5  
概述了用数学模型法预测橡胶贮存寿命的方法,包括阿伦尼斯模型,用ASTM D412评估橡胶拉伸性能,应力应变老化模型,压缩永久变形的预测方法,橡胶疲劳寿命损伤模型,用有限元法考核橡胶的裂纹长度与抗裂能之间的关系,基于叠加原理的寿命预测模型等,针对上述模型预测研究结果提出了相关思考建议。认为以老化动力学为基础预测材料寿命的数学模型法发展非常迅速,建议深入研究并拓宽应用;在透彻了解和掌握必需的分子结构参数的基础上,如果结合计算机技术模拟长期贮存或使用条件,对橡胶老化反应机理的研究可能是一个有前景的发展方向。  相似文献   

19.
State-of-the-art methods of the extraction, preconcentration, and determination of quercetin and other flavonoids are described. Different methods of sample preparation of real samples are compared, including solvent extraction from solid matrices and liquid-liquid, supercritical fluid, and solid-phase extraction. The following main determination methods are discussed: HPLC, thin-layer chromatography, capillary electrophoresis, spectrophotometry, luminescence, and electrochemical methods. Some examples of quercetin determination in biological fluids, food products, biologically active food supplements, pharmaceutical preparations, and plant samples are given.  相似文献   

20.
Fundamentals and fields of application of time- and temperature-resolved diffraction methods are presented. X-ray diffraction and neutron diffraction will be considered. Dynamic diffraction methods are increasingly applied in different fields like solid state reactions, heterogeneous catalysis and biological sciences. New methods like synchrotron radiation and position-sensitive detectors permit a considerable expansion of potential research areas. The dynamic diffraction methods are compared with the classical thermoanalytical methods thermogravimetry and DSC.  相似文献   

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