制备低团聚掺锑氧化锡超细粉体的新方法

以SnCl4·5H2O和SbCl3为原料,用醇盐水解法制备了纳米掺锑氧化锡(ATO)导电粉体。用正丁醇—二甲苯的混合溶剂共沸蒸馏、有机脱水剂以及其它方法对前驱体胶态沉淀进行脱水处理,以消除粉体团聚。运用XRD、TEM、BET等手段对粉体进行表征,比较了各种脱水处理方法对ATO纳米导电粉体的粒度、团聚度、晶粒生长以及电阻率的影响。结果表明,混合溶剂共沸蒸馏处理以及有机脱水剂是比较有效的脱水方法,可以用来制备比表面积大(85.32m2·g—)、团聚小、电阻率低1的纳米ATO导电粉体。     

液相法合成纳米金属氧化物晶体

采用液相法(溶胶-凝胶法)在阴离子交换树脂和乙醇溶剂的辅助作用下直接合成纳米级的金属氧化物晶体和掺杂的金属氧化物晶体,经乙酸异戊酯为溶剂共沸干燥后得到高分散性的纳米微粉.电子显微镜和X衍射光谱的分析,证实了这些高分散性纳米微粉具有明确的晶体结构,并且表现出很高的光催化活性和抗菌灭菌的性能.     

共沸蒸馏法制备单分散氧化镍微粉

先采用均匀沉淀法制得单分散的氧化镍前驱体粉末 ,然后用正丁醇进行共沸蒸馏脱水处理。经干燥、煅烧后成功地制成了单分散性相当好的氧化镍微粉。实验证明 ,共沸蒸馏能有效地脱除湿粉末中的水分 ,丁氧基取代了颗粒表面的羟基 ,从而防止了颗粒间Ni—O—Ni的形成 ,消除了硬团聚形成的可能性。     

醇盐水解法制备二氧化钛纳米粉体

利用控制醇盐水解的方法，分析采用正丁醇共沸蒸馏和乙醇洗涤这两种工艺，详细研究了超细二氧化钛粉体的制备过程，采和ＸＲＤ、ＴＥＤ、ＢＥＴ、ＴＧ和ＤＴＡ等方面对用直接沉淀、正丁醇共沸和乙醇洗涤三种方法获得的粉体进行了表征。发现用直接沉淀和乙醇洗涤法均能获得团聚少、颗粒在１５ｎｍ左右的粉体，且乙醇洗涤能进一步减少粉体的团聚，但共沸蒸馏反而增加了粉体的团聚度。     

不同干燥工艺制备CaO-ZrO_2复合氧化物粉体及粉体性能表征

采用烘箱干燥、乙醇脱水－烘箱干燥及乙醇脱水－超临界流体干燥三种工艺对共沉淀制备的ＣａＯ－ＺｒＯ２复合水凝胶进行脱水处理，考察了干燥工艺对产品粉体性能的影响。结果表明，有机溶剂置换－超临界流体干燥法制备的粉体比表面积和比孔体积都比较大，粒径较小且分布均匀，作为陶瓷及催化材料性能明显优于其他两种方法制备的粉体     

加压干燥法制备无硬团聚氧化铝纳米粉

用加压干燥法制备了粒径５ｎｍ的左右的无硬团聚Ａｌ２Ｏ３纳为粉,对粉体进行了透射电（ＴＥＭ）、Ｘ射线衍射（ＸＲＤ）、热重（ＴＧ）、差热（ＤＴＡ）,比表面积、团聚体密度及粒度分布等表征,加压干燥法是一一种控制硬团聚的有效手段,用此法所得粉体尺寸小,分布均匀、比表面积大,而且无硬团聚体。     

纳米粉体干燥方法的研究

采用三种干燥方法：冷冻干燥、共沸蒸馏和烘箱干燥对溶胶-沉淀法制备的沉淀进行干燥处理,得到了立方相BaTiO₃纳米粉．研究发现：冷冻干燥和共沸蒸馏都能防止粉体中形成硬团聚,提高了烧结活性,其中冷冻干燥法效果更明显．文章同时对两种干燥方法防止硬团聚形成的机理进行了讨论．     

纳米氢氧化钙防团聚干燥研究

干燥阶段的团聚问题是液相法制备纳米粉体的难点之一.本研究分别采用直接干燥法、溶剂置换法、共沸蒸馏法、水介质及异丁醇冷冻干燥法等处理方法制备的纳米氢氧化钙的湿凝胶,表征干燥后,比较不同方法防止纳米粉体团聚的效果,初步探讨了不同干燥工艺的防团聚机理.透射电镜和X射线衍射结果表明,共沸蒸馏干燥法防团聚效果最佳,所得氢氧化钙颗粒最均一并低于50nm,其他方法能不同程度地改善硬团聚,但直接干燥法产物存在硬团聚;而红外光谱分析表明,不同方法所采用的介质均未与氢氧化钙形成化学取代,可能只是以物理吸附的方式改善团聚.     

共沸蒸馏法合成CeO2纳米颗粒研究

分别以乙醇、正丙醇、异丙醇、正丁醇、异丁醇、仲丁醇及叔丁醇等七种有机醇作为共沸剂,采用液相沉淀法结合共沸蒸馏处理前驱体成功合成了分散性良好、粒子尺寸分布为10-20nm的纳米CeO2颗粒,运用TG／DTA、FI—IR、XRD、TEM等方法对不同有机醇的共沸蒸馏作用以及产品性能进行了分析和表征,探讨了共沸蒸馏法制备纳米CeO2的机理。结果表明：共沸蒸馏能起到有效脱除前驱体凝胶中的水分,防止其干燥和焙烧过程中的硬团聚形成的作用,其中七种醇中以正丁醇的共沸蒸馏效果最佳,所得纳米CeO2颗粒的粒度、均匀及分散性能最好。     

阴离子交换合成氧化锌纳米晶体粉新方法及粉体光催化活性

采用一种新型的液相掺杂方法——非水相离子交换除氯法制备掺锑纳米氧化锌。该方法是在中性条件下,严格在控制含水量的低极性溶剂中进行的反应。氯离子的去除与水解是同时进行的,以保证掺杂的准确性及均匀性,提出的乙酸异戊酯共沸蒸馏法回收得到的纳米材料具有高分散性,TEM照片表明其保持了合成时的粒径和形貌。XRD图谱表明,未经煅烧的掺杂纳米氧化锌具有明显晶体衍射峰的晶体。掺杂后纳米氧化锌紫外可见吸收光谱发生了紫移,而紫外的吸收增强,表明锑原子已经掺杂到ZnO的晶格之中。这种半导体材料对甲基红（MR）的光催化降解作用表明,掺杂极大地提高了氧化锌纳米晶体的降解效率,90min内对甲基红（MR）的降解率可高达97％,与纯氧化锌相比,提高了70％以上。     

The effects of hydroxide gel drying on the characteristics of co-precipitated zirconia-hafnia powders

Mixed zirconia-hafnia (Hf_0.25Zr_0.75O₂) powders of fine particle size and narrow particle-size distribution can be prepared via co-precipitation routes using mixed zirconium and hafnium salts as the starting materials. The characteristics of the resultant zirconia-hafnia powders are dependent strongly on the dehydration route by which the co-precipitated hydroxide gels are dried. Zirconium-hafnium hydroxide gels are formed when zirconium and hafnium oxynitrates are co-precipitated in an ammonia solution of pH 10.5. The co-precipitated hydrous gels were dried by three very different routes including organic solvent dehydration, microwave drying, and conventional infrared heating lamp drying. The dried hydroxides were then calcined at various temperatures in the temperature range 550–1150 °C, followed by ball milling to remove large soft-particle agglomerates. The resultant zirconia-hafnia powders were characterized for crystallite size, particle size, particle-size distribution, particle morphology, and the degree of powder agglomeration, using experimental techniques such as X-ray diffraction, BET surface area, differential thermal analysis, thermo-gravimetric analysis, sedigraph, scanning and transmission electron microscopy. Hard particle aggregates, which cannot be effectively eliminated using ball milling, occur in the zirconia-hafnia powders processed via either the microwave drying or conventional infrared heating lamp drying routes. In contrast, the organic solvent dehydration route resulted in an almost aggregate-free powder of fine crystallite and particle sizes. Therefore, the zirconia-hafnia powder processed via the organic solvent dehydration route exhibited high sinterability on sintering at 1300 °C.     

共沸蒸馏法制备超细氧化铝粉体及其表征

用改进的溶胶－凝胶法（ｓｏｌ－ｇｅｌ）制备了单分散纳米级Ａｌ_２Ｏ_３粉体,研究了不同干燥方法对产品粒子性能的影响．结果表明,共沸蒸馏法能够有效地对氢氧化铝凝胶脱水,防止了硬团聚体的形成．在１１５０℃的温度下煅烧,可制得尺寸分布均匀、呈球形的α－Ａｌ_２Ｏ_３超细粉体,其平均粒径为６８ｎｍ．以透射电镜（ＴＥＭ）、Ｘ射线衍射（ＸＲＤ）、热重（ＴＧ）、差热（ＤＴＡ）、比表面测定（ＢＥＴ）等手段对所得的超细Ａｌ_２Ｏ_３粉体进行了表征．     

Ultrafine zinc oxide powders prepared by precipitation/mechanical milling

The synthesis of ultrafine zinc oxide powders using the combination of precipitation and mechanical milling followed by subsequent heat treatment was investigated. Zinc hydroxide/oxidehydrate precursor was prepared by precipitation process using zinc chloride as the starting material. Sodium chloride was added to avoid agglomeration during the mechanical milling process. Zinc oxide particles were formed in the NaCl matrix after heat treatment and obtained after removal of NaCl. The size and structure of zinc oxide powders were studied using X-ray diffraction, transmission electron microscopy, and BET surface area measurements and thermal analysis. This has shown that the particle size of zinc oxide powder is strongly dependent on the weight ratio of sodium chloride and precursor. ZnO particles with an average primary particle size of 15 nm could be obtained when the NaCl/precursor weight ratio was 4 : 1 or above.     

油页岩灰渣提取纳米α-Al_2O_3的方法研究

以油页岩为原料合成纳米α-Al2O3,采用表面活性剂超声辅助分散制备氢氧化铝前躯体,再用共沸蒸馏干燥的综合处理制备超细纳米氧化铝,并以共沸蒸馏法干燥,用XRD、TEM、BET进行分析,用热重/差热、红外、XPS进行表征,实验结果表明,所得的纳米氧化铝分散均匀,粒径为50-80nm,表面活性剂超声结合共沸蒸馏的方法对防止前躯体硬团聚很有效。     

A switchable hydrophilicity solvent mediated process to prepare fine silica aerogel powder as an excellent flatting agent

This work demonstrates a facile two-step method to produce fine silica aerogel powder from silica hydrogel by using N,N-dimethylcyclohexylamine (CyNMe₂) as a CO₂-mediated switchable hydrophilicity solvent. The solvent can almost be totally recycled. More than 70% pore water from silica hydrogel was removed by a quick CO₂ reaction with CyNMe₂ to form a water miscible phase. The silica cake was then dried under ambient pressure with assistance of ethyl acetate as an azeotropic agent. The N₂ adsorption-desorption analysis showed that, the as-prepared silica aerogel powder from a typical hydrogel had a BET surface area of 507.8?m²/g, BJH pore volume of 2.6?cm³/g, and an average pore size of 29.1?nm. The pore volume as well as a narrow particle size distribution (D₅₀?=?6.7?μm) significantly affected the application of the as-produced silica aerogel powder as a flatting agent (FA). Film transmittance index was additionally applied for comparison of the transparence of the applied FA beside the normal extinction index as the performance index. The extinction indices of 61.7 and 52.8% and film transmittance indices of 78.3 and 86.1%, separately for both hydrophobic and hydrophilic applications were measured, hence revealing excellent performance of the as-produced silica aerogel powder.     

Deagglomeration of HA during the precipitation synthesis

Hydroxyapatite (HA) has been widely investigated as bone substitute and/or bone defect repairing material. Many methods to synthesize nano-sized and weak agglomerated HA powders have been developed. However, no method has a satisfactory balance between the powder quality and the production cost. In this study, a simple, cheap and efficient process to prepare nano-sized and weakly agglomerated HA powder was developed, in which ultrasonication and a polymer dispersant of PEG were employed. The synthesized powders were characterized with XRD, TEM, and BET specific surface area analyzer. The results showed that the cooperation of ultrasonication and polymer dispersant greatly weakened the agglomeration in the HA powders, but ultrasonication alone did not influence the agglomeration observably.     

Hydrothermal synthesis and characterization of TiO2 nanostructures using LiOH as a solvent

In the present study, we performed hydrothermal method as a simple and efficient route for the synthesis of rutile TiO₂ nanostructures in various concentrations of lithium hydroxide solutions. TiO₂ nanopowders with average sizes of 15 and 23 nm were prepared using 4 M and 7 M LiOH solutions. X-ray diffraction analysis (XRD), transmission electron microscope (FEG-STEM), scanning electron microscopy (SEM), and Brunauer–Emmet–Teller (BET) analyses were used in order to characterize the obtained products and comparison of the morphology of the powders obtained in different concentrations of LiOH solvent. It was shown that alkali solution concentration has affected the crystallinity, agglomeration ratio, particle size and specific surface area of the obtained rutile phases.