超细BaTiO3粉体制备的研究进展

本文综合评述了超细钛酸钡BaTiO3粉体制备目前采用的各种方法，包括共沉淀法，微乳液法，柠檬酸法，草酸盐法，水热法，溶液热合成法，sol-gel法，金属有机物热解法，有机盐一氢氧化物法。评述了目前对先驱体溶液化学对溶胶的形成，溶胶凝胶转变，粉体的形成影响，以及晶粒尺寸和粒子尺寸与粉体结构的关系。     

激光材料专用YAG粉体制备技术研究进展

本文对国内外目前激光材料专用的YAG粉体制备技术现状做了系统概述。重点介绍了目前YAG粉体制备的几种方法;固相反应法,气相化学法.沉淀法,溶剂热法,溶胶-凝胶法等:并对各种方法的优缺点做了对比:指出以钇铝醇盐为原料,以溶胶-凝胶法为基础制备YAG粉体是最具产业潜力的方法.     

溶胶-凝胶法制备Y3Al5O12粉体的研究

本文以Y2O3、硝酸铝以及柠檬酸为起始原料，采用溶胶一凝胶法合成了YAG粉体，研究了烧成温度及烧成时间对YAG粉体形成的影响，并利用SEM和XRD等实验技术对粉体进行了表征。结果表明，用溶胶一凝胶法成功地合成了纳米YAG粉体(50～70nm)，且随着烧结温度的升高和烧结时间的延长，颗粒尺寸不断增大。     

胶凝剂对Sol-Gel法合成PZT95／5粉体的影响

在以无机盐为主要反应前驱物、水为主要溶剂的溶胶一凝胶法制备PzT95/5粉体中,胶凝剂具有重要的作用.研究表明:胶凝剂主要起到调节溶液pH值的作用.可影响溶胶和凝胶的形成,并影响凝胶的微观结构和PZT粉体的性能;当选用氨水为凝胶剂时,控制pH值在3.5～4.0时对溶胶-凝胶的形成有利,且在700℃/2.5h煅烧后能合成单一钙钛矿相PZT95/5粉体,粉体粒度细且均匀.     

多层陶瓷电容器用的SrTiO3纳米粉体制备

采用溶液-溶胶-凝胶法,从Sr(NO3)2-Ti(OC4H9)4-H2O-C2H5OH体系制备多层陶瓷电容器用的纳米SrTiO3粉体.用热重-差示扫描分析研究了由前驱体干凝胶形成纳米SrTiO3粉体的加热过程.用X射线衍射等方法研究了醋酸、水、温度对凝胶化、纳米SrTiO3粉体的粒径和比表面积的影响.用扫描电镜和透射电镜观察了纳米SrTiO3粉体的形貌和颗粒大小.所制备的SrTiO3粉体分散性好,粒径为40～50 nm,比表面积为9～10 m2/g.     

凝胶预碳化处理对Ca0.4Sr0.6Bi4Ti4O15纳米晶粉体的影响

用凝胶预碳化处理工艺的溶胶-凝胶法制备了晶粒粒径小且分散性能较好的钙锶铋钛(Ca0.4Sr0.6Bi4Ti4O15)纳米晶粉体.借助差热-热重分析仪、X射线衍射仪和扫描电镜等分别确定凝胶的预碳化处理温度,研究了预碳化处理工艺对粉体的物相结构、粉体的微观形貌以及分散性能的影响,并分析讨论了预碳化机理.结果表明:在300℃对前驱体凝胶进行预碳化处理增强了粉体的分散性,降低粉体的粒度,提高粉体的均匀性.凝胶预碳化处理工艺并未对粉体的物相结构造成影响.经过预碳化处理制备的粉体的颗粒尺寸集中在100nm左右;未经预碳化处理的粉体的颗粒尺寸为100nm～1 μm.凝胶预碳化处理后,高吸附活性的有机碳包覆在前驱体的表面是有效减少粉体团聚的原因.     

钇铝石榴石粉体制备方法综述

综述了目前YAG粉体材料的几种合成方法,包括高温固相法、溶胶-凝胶法、燃烧法、喷雾热解法和化学沉淀法(化学共沉淀法、分步沉淀法和改进的化学共沉淀法),总结了每种方法的优缺点,并对YAG粉体材料新的合成工艺进行了展望。     

石榴石型铁氧体粉体的制备工艺研究进展

综合评述了石榴石粉体的种类、性能和合成工艺.对固相合成法、Sol-gel法、共沉淀法、微乳液法、水热法、有机溶剂热合成法等合成石榴石粉体的最近研究进展进行了综合评述.     

纳米β-BiNbO4 粉体的低温合成

对低温合成纳米β—BiNbO4粉体进行了研究。以Bi和Nb的柠檬酸盐为初始原料，采用溶胶-凝胶法,通过控制适当的pH值、温度等条件，可在600℃的低温下热分解获得高温相纳米β—BiNbO4粉体,比普通固相法采用的温度低400℃左右。用红外光谱，热重-差热分析，X射线衍射，液氮吸附法以及透射电镜等手段来表征BiNbO4的柠糠酸盐前驱体及煅烧后粉体的各项特性.结果表明：用柠糠酸盐溶胶-凝胶法制得的β—BiNbO4粉体平均粒径约75nm。比表面积达12．42m^2／g。对形成β—BiNbO4粉体的形成过程及机理进行了初步分析.     

浅析氧化铟锡(ITO)粉体的制备方法和特点

综述了目前ITO粉体的制备方法,其中包括液相共沉淀法、溶胶-凝胶法、水(溶剂)热法、喷雾热解法、燃烧法、机械混合法等,并分析比较了各种制备方法的优缺点。     

Processing and microstructure of γ-LiAlO2 ceramics

γ-LiAlO₂ ceramics with different grain sizes were prepared by controlling the sintering process and regulating the size and shape of the precursor powders. It was found that a size gradation of powders promoted the growth of γ-LiAlO₂ grains. Ceramics with an average grain size of 10 μm were prepared from the size-graded powders. It was demonstrated that the shape of the precursor powders greatly affected the grain growth of the ceramics whereas the granulation of the powders restrained the abnormal grain growth. Furthermore nano-sized precursor powders obtained by a sol–gel route made it possible to prepare nano-structured γ-LiAlO₂ ceramics.     

非水解溶胶-凝胶碳热还原氮化法制备TiN粉体研究

首先,以四氯化钛为原料,异丙醚为氧供体,二氯甲烷为溶剂,采用非水解溶胶凝胶法合成高活性的TiO2凝胶;其次以其为钛源,选用分子量为1300000的聚乙烯吡咯烷酮为碳源,采用碳热还原氮化法合成TiN粉体。X射线衍射仪、场发射扫描电镜和激光粒度仪测试结果表明,与水解法相比,采用非水解法合成的TiO2凝胶经800℃煅烧0．5h仍为活性较高的锐钛矿相,以该凝胶为钛源,经1200℃碳热还原氮化2h可合成纯度相对较高的TiN粉体,将合成温度升至1300℃还原氮化5h可合成更高纯度的TiN粉体。TiN粉体颗粒呈近似球形,发育较好,粒径在1μm以下,激光粒度测定粒径主要集中在10μm左右,d50为8μm。     

Synthesis of high purity 110 K phase in the Bi(Pb)-Sr-Ca-Cu-O superconductor by the sol-gel method

(BiPb)₂Sr₂Ca₂Cu₃O_x superconductor powders were synthesized by the sol-gel method using an aqueous solution of metal nitrates containing polyacrylic acid and tartaric acid as chelating agents. The conditions of the sol formation were determined and the thermal decomposition process of the gel precursor was examined. The effect of sintering temperature on the particle morphology was also investigated. High purity Bi(Pb)-Sr-Ca-Cu-O superconducting oxide powders with high-T_c phase could be obtained and they exhibited sharp superconducting transition with zero temperature of 105 K.     

The role of the synthesis route to obtain densified TiO2-doped alumina ceramics

Alumina specimens doped with 1 wt.% of titanium oxide were successfully prepared by three different synthesis routes: Pechini method, coprecipitation and sol–gel processes. This paper describes the phase sequence in each synthesis process and its effect on the final particle size and shape, as well as, on the microstructure of the calcined powders and the sintering behaviour. The intermediate phases to obtain α-alumina were κ-Al₂O₃, θ-Al₂O₃ and γ-Al₂O₃for the Pechini, coprecipitation and sol–gel processes, respectively, as could be detected by FT-IR and XRD. Secondly, the calcined powders were isopressed and sintered at 1625 °C for 4 h. Density measurements, and microstructure were investigated by Archimedes method and TEM/SEM, respectively. The sintering behaviour of the materials is discussed on the basis of the characteristic of the metastable phases obtained by each route. Coprecipitation yielded rounded particles with the smallest size. Sol–gel process produced larger grains with vermicular shapes and Pechini method led to hexagonal corundum crystals.     

Synthesis and characterization of copper gallium diselenide powders prepared from the sol–gel derived precursors

Copper gallium diselenide (CuGaSe₂) powders were synthesized via the sol–gel method followed by a selenization process. The sol–gel process can effectively reduce the required synthesis temperature to 400 °C due to enhanced reactivity and improved composition homogeneity. The amount of Cu₂Se impurity phase was decreased when sufficient Ga³⁺ was added to the precursors. CuGaSe₂ powders were successfully prepared when the Ga³⁺/Cu²⁺ molar ratio was increased to 2. The formation of CuGaSe₂ with a pure chalcopyrite structure was confirmed via the Rietveld refinement analysis. With decreasing Ga³⁺/Cu²⁺ molar ratios, the particle size of the prepared CuGaSe₂ powders was significantly enlarged because the copper selenide phase acted as a flux for the particle growth. The optical absorption spectra revealed the obtained CuGaSe₂ to have a band gap of 1.68 eV. The sol–gel method combined with the selenization process was demonstrated to provide a potential approach for fabricating CuGaSe₂ materials.     

Sol-Gel synthesis and characterization of SiC–B4C nano powder

In the present research, SiC–B₄C nano powders were synthesized through sol–gel process in water–solvent–catalyst–dispersant system. In order to evaluate the formation mechanism of the product during sol-gel process, TEM, SEM, DTA/TG, BET, XRD, FTIR and DLS analysis methods were employed. The nanometric size of precursor was controlled by dispersing agents and controlling pH inside the sol. DLS analysis revealed that the particles of the precursor inside the sol were below 10 nm. FTIR results indicated that the (Si–O–B) bonds were formed in the dried gel powder, due to hydrolysis and condensation reactions. DTA analysis confirmed that the synthesis temperature was lower than 1400 °C. XRD results implied the presence of cubic β-SiC and the rhombohedral B₄C phases, which were formed simultaneously in the SiC–B₄C nanopowder. BET analysis indicated a high surface area for the particles of about 171.42 m²/g, and that the surfaces of these particles were meso porous. SEM analysis exhibited that SiC– B₄C particle size was in the range of 20–40 nm with homogenous morphology. Ultimately, the TEM/EDS microstructural analysis showed that B₄C and SiC particles were formed simultaneously and uniformly in the final product.     

Sol–Gel Processing and Characterization of Phase-Pure Lead Zirconate Titanate Nano-Powders

The present research describes a modified sol–gel technique used to obtain nano-crystalline lead zirconate titanate (PZT) powders by using triethanolamine (TEA) as a polymerizing agent. The metal ions chemically interacted with TEA in the precursor sol and gel under refluxing conditions. Drying and aging treatments led to development of a precursor–polymeric gel network. A single-phase perovskite structure was formed at 470°C. The PZT gel and powders were characterized by using X-ray diffraction, simultaneous thermal analysis, and Fourier transform infrared spectroscopic techniques. The nano-crystalline morphology was examined by using a transmission electron microscope (TEM). The average particle size determined from TEM was less than 15 nm.     

Synthesis of lutetium aluminum garnet powders by nitrate–citrate sol–gel combustion process

Polycrystalline lutetium aluminum garnet (Lu₃Al₅O₁₂) powders were prepared by a simple sol–gel combustion method using aluminum nitrate, lutetium oxide and citric acid as the starting materials. The XRD results showed that the amorphous precursor converted directly to pure LuAG at 900 °C. The TEM investigations revealed that the synthesized LuAG powders are nano-sized with an average particle size 20–30 nm.     

溶胶-凝胶法制备氧化铝-氧化锆复合粉体

以A1C13·6H2O和ZrOCl2·8H2O为起始原料、NH3·H2O为沉淀剂,采用溶胶一凝胶法制备A12O3含量为51．74％（质量分数,下同）、ZrO2含量为44．95％的A12O3-ZrO2复合粉体。借助X射线荧光分析仪、X射线衍射仪、高温热重仪、激光粒度分析仪和扫描电子显微镜对复合粉体的化学成分、物相组成和粒径分布等进行了表征。结果表明：A12O3-ZrO2复合粉体化学成分均匀性好,粒径较细,粒径小于0．5μm的约为5％,在0．5～5．0μm的约为55％,大于5．0μm的约为40％;随热处理温度升高,复合粉体析晶程度逐渐提高,800℃热处理时t-ZrO2相析出量较少;12O0℃热处理时则析出大量的t-ZrO2相、少量刚玉相和微量c-ZrO2相;1350℃后,刚玉相和c-ZrO2相数量明显增多。