纳米TiO2粉晶的正电子湮没寿命谱研究

用溶胶－凝胶法制备了纳米ＴｉＯ２微粉。应用正电子湮没寿命谱研究了纳米ＴｉＯ２的界面结构。ＰＡＴ研究表明，ｓｏｌ－ｇｅｌ法制备的纳米ＴｉＯ２微粉中只存在两类缺陷，即与短寿命成分ｔ１对应的单空位尺寸的自由体积缺陷，以及与中等寿命成分τ２对应的微孔洞缺陷。     

TiO2-SiO2复合半导体气凝胶制备及光催化活性研究

ＴｉＯ２－ＳｉＯ２复合半导体气交是一种新型纳米光催化氧化剂。本文以正硅酸乙酯、钛酸丁酯为原料,用溶胶－凝胶法经超临界干燥制备出了ＴｉＯ２－ＳｉＯ２复合半导体气凝胶。研究了ＴｉＯ２：ＳｉＯ２不同配比对溶胶－凝胶过程的影响;用ＢＥＴ、ＸＲＤ、ＳＥＭ、ＴＥＭ等测试方法对其结构进行了表征;以苯酚为探针考察了ＴｉＯ２－ＳｉＯ２复合半导体气凝胶的光催化氧化活性,并与普通锐钛矿型钛白粉光催化剂进行了对比结果表明     

纳米晶体TiO2多孔膜的制备,性能及其在太阳能电池中的应用

采用溶胶－凝胶法制备出ＴｉＯ２纳米晶胶体，通过丝网印刷技术直接在导电玻璃基底上的制成胶体膜，经烧结处理得到海绵状的厚约１０μｍ纳米晶ＴｉＯ２膜，由于该膜的纳米结构和多孔性使其表面积比密实的膜高１０００倍左右，基于纳米晶体ＴｉＯ２半导体多孔膜和具有卓越光性能的有机染料光敏化剂，一种低成本，高效率的新型的太阳能电池应运而生。     

溶胶—凝胶法制备有机改性SiO2—TiO2涂层的研究

用溶胶－凝胶法在ＰＭＭＡ上制得ＳｉＯ２－ＴｉＯ２涂层。溶胶粘度分析表明，溶胶以线性生长方式凝胶，适宜于制备薄膜。ＦＴＩＲ对涂层的干燥和热处理过程研究表明，涂层中形成Ｓｉ－Ｏ－Ｔｉ－Ｏ－Ｓｉ无机网络结构。扫描电镜对涂层中Ｔｉ－Ｓｉ元素的分布进行了能谱分析，发现无机网络主要分布于涂层的表面及界面处。     

Al2O3—SiO2—TiO2复合陶瓷薄膜的制备与结构

本文利用Ｓｏｌ－Ｇｅｌ法制备了Ａｌ２Ｏ－ＳｉＯ２－ＴｉＯ２复合陶瓷薄膜，讨论了主要内容是体系成分（Ａｌ：Ｓｉ：Ｔｉ摩尔比）对落膜制备过程及结构的影响。通过分步水解法可以得到稳定的Ａｌ２Ｏ３－ＳｉＯ２－ＴｉＯ２复合溶胶，进而制备复合陶瓷薄膜。组分间的静电作用是溶胶凝结的原因。三组分中，Ｓｉ／Ｔｉ摩尔比是决定溶胶稳定性的主要因素。通过ＸＲＤ对薄膜的相组成进行了分析，表明复合薄膜由Ａｌ４Ｔｉ２ＳｉＯ１２     

超临界流体干燥法制备纳米级TiO2的研究

本文以廉价无机盐为原料,采用溶胶－凝胶法结合超临界流体干燥制备了纳米级ＴｉＯ２,并采用ＸＲＤ,ＤＴＡ－ＴＧ、ＴＥＭ技术研究了Ｓｏｌ－Ｇｅｌ过程中溶液的ＰＨ值、浓度、陈化时间及ＳＣＦＤ技术等条件对ＴｉＯ２粒径大小的影响。     

纳米 TiO2的高分子"锚定位"包覆

通过多组分溶液的原位合成方法,成功地制备了ＴｉＯ２／聚苯乙烯－马来酸酐（ＰＳＭＡ）纳米复合材料．红外普图（ＩＲ）分析了这种材料的化学构成,证明纳米ＴｉＯ２与高分子是以共价键的形式存在．随着反应条件的改变,透射电镜（ＴＥＭ）观察到了纳米ＴｉＯ２在复合物中有规律的形貌变化．综合实验结果,提出高分子“锚定位”包覆的作用模型,形象地说明了这种材料以三维网络、纳米晶ＴｉＯ２微相分离的形式存在,同时ＴｉＯ２颗粒的团聚几率在相当大程度上得以降低．结合Ｘ射线衍射,还确定出了复合物中纳米ＴｉＯ２的锐钛矿型结构．     

纳米TiO2的高分子锚定位包覆

通过多组分溶液的原位合成方法,成功地制备了ＴｉＯ２／聚苯乙烯－马来酸酐纳米复合材料,红外谱图分析了这种材料的化学构成,证明纳米米ＴｉＯ２与高分子是以共价 形式存在。随着反应条件的改变,透射电镜观察到了纳米ＴｉＯ２在复合物中有规律的形貌变化。     

纳米TiO2粉晶的XRD研究

用溶胶－凝胶法制备了纳米ＴｉＯ２粉晶,对不同温度自理的系列粉末用Ｘ射线衍射进行了研究,发现所得粉晶随热处理温度的不同发生了从锐钛矿到金红石相的转变。对系列粉晶进行了Ｘ射线衍射点阵参量计算,结合所得的晶粒度和微结构参数,发现纳米ＴｉＯ２粉晶组元中存在着晶格畸变。     

纳米级ZnO—TiO2复合粉体的制备及其性能表征

利用ＺｎＳＯ４和Ｔｉ（ＳＯ４）２为原料,在合成纳米ＴｉＯ２粉体的基础上,将ＴｉＯ２微粉分散在（ＮＨ４）２ＣＯ３溶液中,进一步将ＺｎＣＯ３的形成沉淀出来,于３００℃煅烧２ｈ,即可制得纳米级ＺｎＯ－ＴｉＯ２复合粉体,其粒径约３０－９５ｎｍ。     

油酸修饰对纳米二氧化钛在变压器油中分散性的影响

利用油酸对纳米二氧化钛进行有机表面修饰, 将修饰后的纳米粉体超声分散到变压器油中制备纳米二氧化钛改性变压器油, 研究了表面修饰对纳米二氧化钛在变压器油中分散性的影响. 采用X射线粉末衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和热分析(TG)对纳米二氧化钛的形貌、结构和表面修饰状态进行表征。结果表明, 油酸与纳米二氧化钛表面以双齿桥连配位方式键合, 在纳米二氧化钛表面形成了良好的修饰层。随着修饰剂的增加, 尽管油酸在纳米二氧化钛表面的配位方式没有发生改变, 但化学包覆量明显增加, 表面油酸分子的排列也更为紧密, 从而使纳米二氧化钛粒子在变压器油中的分散性和稳定性显著提高。当钛盐与油酸摩尔比为1:24时, 二氧化钛纳米粒子可以稳定分散在变压器油中, 室温静置30 d后仍保持澄清透明。     

One-pot synthesis of oleic acid modified monodispersed mesoporous TiO2 nanospheres with enhanced visible light photocatalytic performance

Herein, we report a facile one-pot solvothermal method to prepare unique oleic acid (OA) modified monodispersed mesoporous TiO₂ nanospheres with carboxylate ligands from the oleic acid in the bidentate chelating linkage mode. The mesoporous OA-TiO₂ nanospheres have a very large specific surface of nearly 510?m²/g. The oleic acid cannot only act as a binding ligand to control the shape of mesoporous TiO₂ nanospheres, but also be benefit to enhance the visible-light absorption. The mesoporous OA-TiO₂ nanospheres exhibit an excellent photocatalytic performance in the degradation of Rhodamine B and phenol under the visible light irradiation and show almost no attenuation after four cycles.     

棒状和球状氧化锌微晶的控制合成及其表征

以醋酸锌和尿素为主要原料,利用微乳-溶剂热法控制合成了棒状和球状ZnO微晶.用XRD、TEM、FTIR.和SAED等技术手段对两种形状的ZnO微晶进行了表征.结果表明:棒状ZnO微晶的平均尺寸为50nm×320nm,球状ZnO微晶的平均尺寸约为200nm.     

采用油酸和月桂酸改进磁流变液稳定性的实验研究

鉴于油酸和月桂酸2种表面活性剂对磁流变液稳定性所起到的不同的作用,制备了若干种不同配比的以油酸和月桂酸共同添加的磁流变液,测量它们的零场粘度、力学性能和沉降率-时间曲线,研究了月桂酸、油酸和羰基铁粉3种成分的含量对于磁流变液稳定性和力学性能的影响。结果表明合理的添加油酸和月桂酸对于制备零场粘度小且稳定性优良的磁流变液具有显著的效果。     

溶胶-凝胶法制备稀土掺杂多孔TiO2薄膜的表面形貌及性能研究

以溶胶－凝胶法,采用旋转涂膜工艺在玻璃表面制备了Ce,La掺杂的多孔TiO2薄膜,研究了玻璃表面TiO2薄膜在稀土掺杂及多孔化处理后的特征,发现稀土元素的掺杂使薄膜的多孔结构更加均匀一致,在近紫外的吸收率明显提高,同时对油酸有更高的光催化降解效率。     

Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

Oleic-acid-coated CoFe₂O₄ nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism dominates to the region where mono-domain ferrimagnetism dominates the magnetic properties.     

Synthesis, Microstructure and Optical Absorption of Coatingswith Doping of Nano-TiO2 for Protection Against UltravioletIrradiation

1. IntroductionThe paint suffering from long-term irradiation ofthe sunlight will degrade due to the photochemical effect. The addition of the conventional organic ultraviolet light absorber into the surface paint is usuallyused to prevent long term degradation of the paint.However, the organic ultraviolet light absorber possesses some shortcomings, such as short life and toxicetc. The nano--TiOZ powder is a strong ultravioletlight absorberll] and can overcome the above mentioned shortcoming…     

Hydrophobic and water-resisting behavior of Portland cement incorporated by oleic acid modified fly ash

The water-repellent and anti-permeability properties of cement are crucial for the durability and safety of concrete structures. In this work, we prepared a hydrophobic Portland cement by using oleic acid as a modifier for fly ash and examined the properties of the cement paste samples. Fly ash was firstly reacted with oleic acid by the dry milling method, and the modified fly ash was used to prepare the hydrophobic Portland cement. The IR spectra confirmed that the surface of fly ash was successfully capped with oleic acid, and carboxylic acid moieties were bonded with ≡SiOH and neutralized. The TG-DSC results showed that the amount of oleic acid loaded on the fly ash beads was 7.21 wt%. Fly ash dispersed evenly in the prepared cement paste samples and the distance between beads ranged in 2–10 μm. The water contact angle of the cement paste samples increased with rising content of modified fly ash, which demonstrated good water-repellent behavior. Different cement sections showed similar water-repellent behavior, which proved that the inner structure of the cement was also hydrophobic. Using the fly ash modified with oleic acid significantly decreased the water uptake and gas permeability of the prepared cement paste samples. The hydrophobic cement sample was optimal when the content of the modified fly ash in the cement was 12 wt% and after the cement was cured for 28 days.     

A novel aqueous-phase route to synthesize hydrophobic CaCO3 particles in situ

Hydrophobic CaCO₃ particles were prepared in situ by carbonation of Ca(OH)₂ slurry in the presence of the ethanol solution of oleic acid by mimicking the process of biomineralization. The weight ratio of oleic acid to CaCO₃ changed from 0.3 to 3 wt.%. By changing the weight ratio of oleic acid to CaCO₃, the surface property of CaCO₃ particles was changed from hydrophilic to hydrophobic. Floating test and contact angle analysis of the obtained product indicated that the final CaCO₃ obtained was hydrophobic. From the floating test, the active ratio of the modified CaCO₃ might reach 100%. The contact angle of the modified CaCO₃ was 108.77. IR spectrums of the CaCO₃ particles showed the appearance of the alkyl groups from the oleic acid. We have succeeded in surface modification of CaCO₃ with the hydrophobic oleic acid.     

Optimisation of ligand exchange towards stable water suspensions of crystalline NaYF4: Er3+, Yb3+ nanoluminophors

NaYF4: 2%Er3+, 20%Yb3+ nanoparticles were synthesized through a wet chemical route. In order to transfer the nanoparticles from chloroform to aqueous solution an oleic acid to 3-mercaptopropionic acid ligand exchange process has been performed and optimized. The influence of temperature and atmosphere onto the NaYF4:2%Er3+, 20%Yb3+ nanoparticles water suspensions dispersibility and stability after replacing oleic acid with 3-mercaptopropionic acid ligands has been investigated. The results revealed an improvement of nanoparticles water suspension transparency and luminescence yield after ligand exchange process performed under inert atmosphere and at elevated temperature.