BaTiO3纳米晶的合成与表征

以硬脂酸、硬脂酸钡和钛酸丁酯为原料合成了ＢａＴｉＯ３纳米晶，粒度为１０～２０ｎｍ，烧成温度为６５０℃，低于传统的合成温度。用红外光谱、差热分析、热重分析和Ｘ射线衍射对合成过程进行了研究，用透射电镜考察纳米晶的粒度和形貌。用发射光谱和Ｘ射线荧光光谱对样品纯度进行了分析。结果表明，此法合成的纳米晶ＢａＴｉＯ３纯度高、粒度小且较均匀，在常温下属立方钙钛矿型。     

纳米晶LaCoxFe1-xO3的合成、表征及湿敏特性

采用PEG溶胶-凝胶法合成了纳米晶LaCoxFe1-xO3, 并用DTA-TGA、XRD以及SEM对样品进行表征. 结果表明, 所有样品的原粉在600 ℃焙烧下都形成了稳定的钙钛矿纳米晶, Co含量对形成纳米晶的固相反应和纳米晶的平均粒子尺寸都有明显的影响. 此外, 还研究了纳米晶LaCoxFe1-xO3的湿敏特性, 发现在所有的样品中, LaCo0.3Fe0.7O3表现出比其它样品好的湿敏特性, 但是此材料只在相对湿度(RH)大于54%时对湿度的变化有较高的灵敏度, 掺杂适量的Na2CO3可以改善此材料的湿敏特性, 使它在全程湿度范围(RH 11%-95%)内对湿度变化都有很好的响应.     

荧光CdS纳米晶的合成与表征

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.     

Silica lite-1纳米晶的尺寸控制合成

全硅 Silicalite- 1沸石作为 MFI结构的 ZSM- 5分子筛家族中不含 Al的成员 ,不仅具有良好的热稳定性和特殊的十元环孔道结构 ,而且具有憎水和亲油等特性 [1,2 ] ,通常以四丙基铵根离子为模板剂在水热条件下进行合成 ,所得到的晶粒尺寸处于几微米至几十微米之间 [2～ 11] .如李军等 [3 ] 制得了晶粒在1 0μm左右的 Silicalite- 1膜 . Kath等 [4 ] 以硅酸铵为硅源、四丙基溴化铵为模板剂制备了粒径为 5 0μm的 Silicalite- 1 ;但以正硅酸乙酯为硅源、四丙基氢氧化铵为模板剂时 ,在乙醇的参与下合成了晶粒为0 .5 μm的超细 Silicalite- 1…     

超细YF_3与GdF_3纳米晶的合成及其上转换发光

当使用液固溶法(LSS法)制备分散性纳米晶时,将传统油酸/油酸钠/酒精反应体系中的NaOH用氨水取代时,氨水将会与油酸形成新的表面活性剂油酸铵,这样就可以合成各种超细分散性的REF3纳米晶(RE代表稀土元素)。在这种新的反应体系中,合成了平均直径小于10 nm的YF3和GdF3超细颗粒,X射线与透射电镜测试表明YF3是正交相,而GdF3是面心立方结构,空间群为Fm3m,晶格常数为0.582 9 nm。在980 nm半导体激光器激发下,可检测到YF3∶Yb/Er在515~570 nm处有较强的绿色发光峰、645~675 nm处有较强的红色发光峰,呈橙色发光。YF3∶Yb/Tm和GdF3∶Yb/Tm样品在460~490 nm处有较强的蓝色发光峰,而在800 nm附近有更强的近红外发光峰。由于其超细的尺寸及红外上转换发光特性,合成的样品在生物成像、生物标签等方面有潜在的应用价值。     

LaZnxFe1-xO3 钙钛矿型纳米催化剂的制备、表征及其甲苯燃烧性能

 Nanostructured LaFeO3 and substituted LaZnxFe1-xO3 (x = 0.01, 0.05, 0.1, 0.2, and 0.3) perovskites were synthesized by the sol-gel auto-combustion method and used in the catalytic combustion of toluene. Their structures and surface properties were investigated by X-ray diffraction, Fourier transmission infrared spectroscopy, BET surface area, and scanning electron microscopy. Characterization data revealed that the total insertion of zinc into LaFeO3 takes place when x ≤ 0.1. However, ZnO segregation occurs to some extent, especially at x > 0.1. The performance of these perovskites was evaluated by toluene combustion. The catalytic activity of the catalysts increased substantially with an increase in zinc substitution. These results can be attributed to the cooperative effect between LaZnxFe1-xO3 and the zinc oxide phases. The relative concentration of these phases determines their oxygen activation ability and reactivity.     

Fe1-xO基氨合成催化剂的制备化学

采用高温熔融法制备了各类铁氧化物,用XRD分析了熔融过程中的物相变化,EOS考察了熔融体凝固-冷却速率对助催化剂分布的影响.结果表明,采用大气气氛中的高温熔融法不能制取Fe₂O₃和化学计量比的FeO,前者会发生分解反应,后者会发生歧化反应;在1.333≤n(O)/n(Fe)<1.38范围时,可以制取Fe₃O₄或非化学计量比的Fe₃-yO₄;在1.113O₄和FeO的混合氧化物;在1.0451-xO,即维氏体.Fe_1-xO基催化剂的制备必须采用物理熔融与化学反应相结合的工艺.凝固冷却速度对抑制氧化亚铁的氧化反应和歧化反应,保证助催化剂的均匀分布和晶粒度均有很大影响     

La_(0.5)Na_(0.5)TiO_3纳米晶的制备及光致发光研究

以硬脂酸、硝酸镧、氢氧化钠和钛酸四丁酯为原料制备了La0 .5Na0 .5TiO3 纳米晶 ,粒度最小可达 1 4nm ,烧成温度为 50 0℃ ,低于传统固相反应的合成温度。光致发光研究表明 :用 392nm光作激发光 ,在室温下观察到了一个强的蓝光发射带 ,并且它的强度和半宽度随粒度发生明显变化。     

Fe3O4纳米晶的简单调控合成、表征及磁性能

采用醋酸铵作保护剂在200℃下制备了单分散的400 nm粒径的Fe3O4空心纳米球.通过改变实验条件,对产品的形貌、内部结构和粒径进行了调控合成,得到了粒径范围在100～200 nm的实心纳米球和片形结构的Fe3O4纳米材料.采用SEM、TEM和XRD等对样品进行了表征.结果表明,所得尖晶石型Fe3O4纳米晶粒径均匀,分散度好.利用振动样品磁场计检测了不同形貌样品的磁性能.结果显示,Fe3O4纳米空心球的饱和磁化强度和矫顽力均大于Fe3O4纳米片的对应值.     

蒸气促进干胶法合成硅胶负载的TS-1纳米晶

采用蒸气促进的干胶法, 在工业硅胶上原位合成出TS-1纳米晶. 先用TS-1合成液浸渍硅胶, 再于130 ℃下和水蒸气作用2 d, 得到硅胶上负载的TS-1纳米晶. 采用XRD, FTIR, UV-Vis和NMR谱以及N2吸附、 ICP、 SEM和TEM等对所得样品进行了表征. 结果表明, 将TS-1纳米晶负载在硅胶上, 其晶粒大小为20 nm左右, Ti进入了分子筛的骨架; 所得的TS-1/silica gel复合材料的比表面积为113.2 m2/g, 平均中孔孔径达到23.7 nm. 将其用于苯的羟基化反应, 以n(C6H6)/n(H2O2)=3进料, 环丁砜为溶剂, 于100 ℃下反应2 h, 苯的转化率达到8.7%, 苯酚的选择性超过99%, 苯的氧化速率(TOF)为11.37, 其催化活性明显高于传统水热合成的TS-1.     

Mossbauer Investigation of Nanocrystalline LaFeO3 Materials

Introduction Owing to their potentially physical, mechanical and chemical properties nanocrystalline solid materials have recently received considerable attention. Mssbauer effect has been proved to be highly useful for studying nanocrystalline solid material and has been applied to the investigation of the magnetic properties and     

溶胶—凝胶法合成LaCr1—xFexO3超细粉末

以无机盐为原料，用溶胶－凝胶法合成了ＬａＣｒ１－ｘＦｅｘＯ３超细粉末，其平均粒径〈１３０ｎｍ。研究表明，随着焙烧温度的升高或时间的增加，粉末的粒径随之增大，比表面积则随之减小；ＬａＣｒ１－ｘＦｅｘＯ３粉末为钙钛矿型结构，其晶胞参数随着Ｆｅ含量的增加而增大。     

Preparation of c-Axis Oriented LiNb1-xTaxO3 Films on Si(111) Substrates by a Modified Sol-gel Process

IntroductionLi Nb O3 and Li Ta O3 are two excellentferroelectric materials similar in structure andcomplementary in some properties. Numerousattempts have been made on the deposition of thinfilms of Li Nb O3 and Li Ta O3 by means of differenttechniques[1— 6] . In order to combine the opticalproperties of Li Nb O3 and Li Ta O3 with the electricalproperties of silicon,it is of great importance togrow epitaxial or,at least,c- axis orientedLi Nbx Ta1-x O3 films on silicon substrates for b…     

钙钛矿型LaFe1-xCuxO3的光催化活性研究

用柠檬酸络合法制备了钙钛矿型LaFeO3及LaFe1-xCuxO3化合物，测定了其对酸性红3B等水溶性染料的光催化降解活性。利用红外、紫外和光声光谱、正电子寿命谱及光电子能谱等技术分析了LaFeO3的光催化性能及掺杂对其活性的影响。结果表明，掺杂Cu^2 可使LaFeO3的光催化活性明显提高。     

溶胶凝胶法制备钇掺杂锂离子电池正极材料LiCo1/3Ni1/3Mn1/3O2

采用溶胶凝胶方法制备了LiCo1/3Ni1/3Mn1/3O2正极材料，研究了不同掺杂量的Y对于LiCo1/3Ni1／3Mn1/3O2材料结构和性能的影响。研究发现，掺杂量〉1％后Y不能很好地融入材料的晶格之中。电化学性能测试结果表明，少量Y的掺杂（1％～3％）可以明显改善LiCo1／3Ni1／3Mn1/3O2材料的循环性能。     

Ti:Al2O3纳米粉体的共沉淀法合成及表征

本文采用共沉淀法合成了Ti:Al2O3纳米粉体.利用热重/差热(TG/DTA)/X射线衍射(XRD)/红外光谱(FTIR)/扫描电镜(SEM)以及能谱(EDS)等分析方法对合成的Ti:Al2O3纳米粉体进行了表征.结果分析表明:前驱体在1200℃下,保温1h可以得到纯的α-Al2O3晶相;粉体的粒径均匀、分散性好,平均粒径在25～50 nm之间.     

Effect of Various Synthesis methods on the Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2

Layered LiNi1/3Co1/3Mn1/3O2 has the isostructure of α-NaFeO2 and shows high rate capacity with stable cycleability. Furthermore, the thermal behavior of this material is milder than that of lithium nickel oxide and lithium cobalt oxide. In addition, it is expected to be stable at elevated temperatures. Therefore LiNi1/3Co1/3Mn1/3O2 may be the most promising cathode materials of lithium-ion secondary battery.In this research, LiNi1/3Co1/3Mn1/3O2 was prepared by solid-state reaction, sol-gel method and mixed hydroxide method. The influences of synthesis method on the physical and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), charge/discharge cycling cyclic voltammetry and differential scanning calorimetry (DSC). XPS studies show that the predominant oxidation states of Ni, Co and Mn in the LiNi1/3Co1/3Mn1/3O2 compound are 2+, 3+ and 4+. From the voltage profile and cyclic voltammetry, the redox processes occurring at ～3.8V and ～4.5V are assigned to the Ni2+/Ni3+ and Co3+/Co4+ couples, respectively. Different preparation methods result in the difference in morphology (shape, particle size and specific surface area) and electrochemical behaviors. A sample prepared by solid-state reaction has the worst electrochemical performance among these three methods. Sample synthesized by mixed hydroxide method displays the better rate capacity than that prepared by sol-gel method, while the capacity retention of sample prepared by sol-gel method is superior to that synthesized by mixed hydroxide method.