水热反应条件对合成BaTiO3纳米粉体影响的研究

通过正交实验法,对不同钡钛比、反应温度、保温时间进行了水热合成钛酸钡纳米粉体的实验研究,对所得粉体进行了DTA,XRD,TEM等分析表征,分析研究了不同水热反应条件对合成钛酸钡纳米粉体的影响。     

掺镧改性BaTiO3纳米多晶粉体的综合性实验设计

纳米粉体的合成与掺杂改性研究为当今材料科学与工程研究领域极为重要的研究课题之一。为了让材料化学类本科生了解和掌握无机材料纳米粉体的制备、表征等研究方法,在大量研究工作的基础上,我们设计了关于掺镧改性钛酸钡纳米多晶粉体制备及其结构表征的综合性实验,包括溶胶-凝胶法制备掺杂镧的BaTiO3纳米粉体,利用DTA、XRD、SEM等测试手段对纳米粉体进行结构表征等实验内容。     

低温制备钛酸钡纳米粉体方法的研究

本文以钛酸四丁酯和乙酸钡为原料,采用溶胶-凝胶法和水热法相结合的方法制备了钛酸钡纳米粉体。我们的工作集中在低温合成工艺,以及所得纳米粉体的结构和形貌表征。     

钛酸钡粉体的微波水热合成

结合水热法和微波加热的优点,采用微波水热在低温条件下合成了钙钛矿结构的钛酸钡纳米粉体,并与水热法合成产物进行了适当的比较。通过X射线衍射(XRD)、红外光谱(IR)和SEM电镜,分析了BaTiO_3纳米粉体的结构和组成,并初步探讨了微波水热合成钛酸钡的机理。结果表明,与传统水热法比较,微波水热合成BaTiO_3纳米粉的温度更低,而且微波加热可明显提高反应速度。     

微波辅助草酸盐沉淀法合成钛酸钡纳米粉体的分散性研究

本文采用微波辅助草酸盐沉淀法在微波条件为80℃,30 min和煅烧条件为700℃,1h的工艺参数下制备了四方相钛酸钡纳米粉体.用X射线衍射仪和透射电子显微镜研究了分散剂种类及用量对钛酸钡纳米粉体的相组成与微观形貌的影响,探讨了其分散机理.结果表明,有着不同分散机理的阳离子分散剂三乙醇胺和非离子分散剂OP-10都能使纳米粉体具有良好的分散效果.当分散剂添加量为3％ ～5％时,分散效果最明显.     

直接沉淀法合成钛酸钡粉体的研究

采用直接沉淀法制备钛酸钡粉体。利用XRD,TEM等检测手段对样品进行了表征。重点研究了直接沉淀法合成钛酸钡的制备方法和影响因素。结果表明,通过该方法合成的钛酸钡粉体为立方晶系,且为均匀球形,粒径分布在50~80nm,纯度为99. 85%。     

微波-沉淀法合成高纯四方相BaTiO3纳米粉体研究

以BaCl_2、TiCl_4为原料,以(NH_4)_2C_2O_4·H_2O为沉淀剂,利用微波-沉淀法制备了高纯四方相钛酸钡纳米粉体。应用XRD、TEM等对粉体的结构、形貌进行了分析。研究表明,微波-沉淀法合成粉体的时间为50 min,制备的粉体属于四方相晶体结构,粒度为30nm、粒度分布均匀,杂质含量达到电子行业工业标准。     

用特殊液相沉淀法制备掺锡钛酸钡纳米粉体

依据反应胶粒析出机理及实验原理，采用高强度快速机械混合沉淀法，控制溶液pH，快速生成沉淀。用NH4OH，NH4HCO3清洗液过滤、洗涤。制备掺锡钛酸钡纳米粉体，当掺Ba（Ti0.9Sn0.1）O3时，该粉体室温介电常数最大，约是BaTiO3的8倍。经TEM和XRD表征，获得的掺锡钛酸钡纳米粉体粒径为48nm，分散性良好。XRD表明适量掺锡进入钛酸钡晶格会引起居里点前移，并作了微观解释。     

钛酸钡纳米粉体表面包覆方法的研究

钛酸钡纳米粉体的表面包覆不仅解决了粉体的团聚和分散问题，而且赋予粉体诸多的优异性能，因此粉体的表面包覆技术受到诸多关注并且已取得了一定的研充进展。文章主要综述了近年来钛酸钡纳米粉体表面包覆方法，以及包覆后对钛酸钡纳米粉体的表面性质乃至粉体的相结构和性质的改善作用。     

粉体的燃烧合成技术及其在钛酸钡粉体制备中的应用

综述了燃烧法合成陶瓷粉体的原理、方法及其在钛酸钡粉体制备中的应用 ,比较了各种燃烧法合成钛酸钡粉体工艺的优缺点 ,并指出目前经济、有效地制备钛酸钡粉体的方法是以有机燃料和金属硝酸盐为原料的低温燃烧合成法。     

Synthesis of barium strontium titanate nanopowders by microwave hydrothermal method

Barium strontium titanate (BST) powders of high purity, good crystallinity and well dispersed with a diameter of 50–90?nm are prepared by microwave hydrothermal method using tetrabutyl titanate, barium nitrate and strontium nitrate as the main raw materials. The phase composition, element composition and microstructure of the powders are characterised by X-ray diffraction, Fourier transform infrared spectroscopy, energy dispersive spectroscopy and transmission electron microscopy. The results show that Ba_0.6Sr_0.4TiO₃ powders could be synthesised under the conditions that the reaction temperature is 70°C, the reaction time is 10?min, and the value of pH is 14, which indicates that the reaction temperature, time and the value of pH have a great effect on the crystallinity of nanopowders, and the dispersant (OP-10) plays a role in the dispersion of the nanopowders.     

具有固定硅铝比的Al2O3-2SiO2纳米颗粒制备:过程优化与粉体转化（英文）

Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane(TEOS) and aluminum nitrate(ANN) as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure(morphology) of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows:the molar ratio of water and ethanol to TEOS are 0:1 and 12:1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m2·g·1.The compressive strength of the geopolymer and the calcium exchange capacity(by CaCO3) of NaA zeolite prepared with the powders reached to 29 MPa and 366 mg·g·1 respectively.     

Sm掺杂BaTiO3纳米粉体的制备与表征

以钛酸四丁酯与醋酸钡为钛酸钡前驱体,PEG为分散剂,硝酸钐为掺杂物种给体,采用溶胶-凝胶法制备改性的Sm掺杂BaTiO3纳米粉体。样品经X射线衍射(XRD)与差热-热重联用(DSC-TGA)的方法对其进行了表征。研究了煅烧温度与分散剂对BaTiO3粉体粒径与相的影响。结果表明:立方相在700～850℃生成,前驱体经950℃热处理制得后呈四方相BaTiO3。分散剂PEG可抑制BaTiO3晶粒增长;随煅烧温度升高,粉体粒径增大。适量Sm掺杂可以抑制杂质BaCO3相的形成。     

水热合成技术的研究和应用──Ⅰ.钛酸盐晶体粉末的制备

应用水热合成法制备钛酸钡、钛酸锶、铁酸钙从钛酸铅晶体粉末，采用的技术路线分别以Ba（OH）2，Ca（OH）2，Sr（OH）2，Ph（OH）2及TiO（OH）2为水热合成钛酸盐的前驱物。研究了它们合成时的KOH浓度、温度和时间等影响因素。根据实验结果．按水热前驱物M（OH）2的特性分类．找出它们的共性和差异，提出了合成机理及MgTiO3和Al2（TiO3）3难以用水热合成的原因。     

热处理温度对掺铁TiO2纳米粉体光催化性能的影响

以硫酸氧钛、九水硝酸铁、钛酸丁酯等为原料,采用均匀沉淀法和溶胶-凝胶法分别合成制备出单一的二氧化钛和掺铁的二氧化钛纳米粉体。利用X射线衍射仪(XRD)和可见光分光光度计等测试手段,研究了热处理温度对掺铁TiO2纳米粉体的晶型和光催化性能的影响,并对掺铁TiO2纳米粉体的晶型和光催化性能之间的相关性的进行了分析。实验数据表明,掺铁TiO2纳米粉体的适宜热处理温度约为400℃。     

微通道反应-水热晶化法制备羟基磷灰石纳米粉体

采用微通道反应与水热晶化相结合的工艺路线,制备HAP纳米粉体。结果表明,增大反应物流量比或减小微通道高度会导致HAP粉体的颗粒粒径变小,增加水热温度或时间会提高HAP的结晶性和热稳定性,反应物流量比和水热温度是影响HAP纳米粉体制备的主要因素。当反应物流量比为5∶1,微通道高度为250μm,220℃下水热4 h时,实验可以制得平均粒径约为80 nm、粒度分布均匀、结晶度高的短棒状HAP纳米粉体。     

超声化学法快速形成钛酸锶铅纳米粉

采用超声化学法方便地制得了Sr1-xPbxTiO3(SPT)纳米粉末.高强度的超声作用促使了SPT纳米颗粒的快速形成.通过控制Sr2 和Pb2 的摩尔比,可以得到不同形貌的SPT纳米粉末:当x=0,可以得到球形的纳米粉末;随着Pb2 含量的增加,SPT纳米粉末的形状由球形变成方形.通过X射线衍射仪对SPT纳米粉末进行表征.结果表明:在固定的起始反应物总浓度下,随着Pb2 含量的增加,所得到纳米粉末的微结构也随之变化.超声化学法合成SPT纳米粉的反应分两个过程进行:首先TiCl4水解形成富钛凝胶;然后在超声影响下,溶液中的Sr2 和Pb2 扩散到钛凝胶表面,并以其为核生成SPT纳米颗粒.     

矿化剂浓度对水热合成BaTiO3纳米粉体影响的研究简

以氢氧化钠做矿化剂,利用钛酸丁酯和氢氧化钡,通过水热法合成了纳米钛酸钡粉体。通过XRD、差热分析和高倍显微镜观察等分析表征手段,对矿化剂加入量对水热合成纳米钛酸钡粉体的影响进行了初步研究探讨。     

Mechanochemical synthesis and investigations of calcium titanate powders and their acrylic dispersions

In this paper we studied calcium titanate (CaTiO₃) nanopowders obtained via a mechanochemical method assisted by microwave irradiation from calcium oxide and titanium dioxide, as well as its suspensions with addition of acrylic-poly(ethylene glycol) suspensions (SAP) obtained using microwave irradiation as a stabilizing agent. Experiments carried out using X-ray diffraction technique confirmed success of mechanochemical synthesis assisted by microwave irradiation and scanning electron microscopy images allowed to determine the structure as well as dimensions of CaTiO₃ nanopowders. Suspensions of CaTiO₃ and SAP were examined and the results showed relationships between the SAP concentration and both viscosity and stability. Both viscosity and stability are significantly increased upon addition of SAP and the dependency is nearly linear for higher SAP concentrations. Based on the results, we conclude that addition of SAP allows to successfully stabilize CaTiO₃ nanopowders and the stabilizing effect can be explained by both electrostatic and steric forces.     

A CTAB-assisted hydrothermal and solvothermal synthesis of ZnO nanopowders

ZnO nanopowders were synthesized by hydrothermal and solvothermal method by using CTAB as surfactant, and the effects of CTAB on the morphologies of ZnO nanopowders were investigated. The results showed that the presence of CTAB could greatly vary the shape of the ZnO crystals. ZnO nanorods were prepared from the hydrothermal system without CTAB and flowers-like ZnO nanostructures were produced from hydrothermal system with 0.4 M and 0.5 M CTAB. Low concentration of CTAB in ethanol was conducive to the formation of ZnO nanorods, but the concentration continued to increase, the morphology of sample transformed into hexagonal bipyramid, and then transformed into spherical. The synthesis mechanism of ZnO powders with different morphologies has been presented.