低压条件下纳米氧化锆的水热结晶合成

本文采用水热结晶法研究了在较低压力下纳米氧化锆粉体的制备的性质。制备出了结晶完整、分散性良好、粒度约为十几纳米的超细氧化锆粉体。淫ＸＲＤ、ＴＥＭ等测试方法对晶相组成、晶貌特征等与水热结晶温度及保温时间的关系进行了研究。并对单斜相氧化锆和四方相氧化锆的晶粒形成过程进行了讨论。     

纳米硅酸锆的合成

利用水热法制备了纳米ZrSiO4粉体，借助XRO，TEM及SEM等研究了ZrSiO4晶粒相组成，粒度和结晶形貌与前驱物Zr和Si的摩尔比，水热反应温度以及反应时间之间的关系，并对ZrSiO4的合成机理进行了实步研究。     

溶胶-胶水热合成法制备纳米CoAl2O4粉体

以仲丁醇铝和硝酸钴为原料,用溶胶-凝胶水热合成法制备了纳米CoAl2O4粉体,探讨了水热合成中前驱体的制备工艺条件,并用X射线衍射和扫描电镜等手段分析了水热系统中反应温度、反应时间对纳米CoAl2O4粉体的形成以及形貌的影响.结果表明:前驱体在250℃的水热系统中反应24 h,能制备出较纯净、结晶完整、粒度均匀、粒径小、尖晶石结构的纳米CoAl2O4粉体,其平均粒度约为50～60nm.     

常压水热合成纳米氧化锆工艺研究

以ZrOCl2.8H2O和氨水为主要原料,利用常压水热工艺制备出纳米氧化锆粉体,系统研究了氧氯化锆浓度、pH、反应温度及时间对产物晶型、粒度的影响,得出制备氧化锆纳米粉体的最佳工艺条件。并结合X射线衍射分析、透射电镜等方法对样品进行表征。结果表明,所制得的氧化锆样品为纳米氧化锆粉体,且粒度较均匀、分散性好,平均粒径约为7 nm。     

水热法制备球形二氧化锆粉体的研究

以氯氧锫为前躯体通过水热法制备出了粒径在5μm左右,粒度分布均匀的球形二氧化锆粉体.研究结果表明水热温度、水热时间以及醇水比例对产物的微观结构均有影响.140℃水热处理24h获得产物为无定型态的氢氧化锆粉体,而200℃水热处理24h可获得单斜和四方混相的二氧化锆粉体.随水热时间的延长,产物相结构经历了由无定型氢氧化锆向单斜与四方混相的二氧化锆转变,相转变机制则经历了由均匀饱和析出机制到溶解沉淀为主、原位结晶为辅机制再到原位结晶为主、溶解沉淀为辅机制的变化过程.     

纳米硅酸锆的水热合成

利用水热法制备了纳米ＺｒＳｉＯ４粉体,借助ＸＲＤ,ＴＥＭ及ＳＥＭ等研究了ＺｒＳｉＯ４晶粒相相成,粒度和结晶形貌与前驱物Ｚｒ和Ｓｉ的摩尔比,水热反应温度以及反应时间之间的关系,并对ＺｒＳｉＯ４的合成机理进行了初步研究。     

纳米氧化锆粉体的制备

归纳、总结了纳米氧化锆粉体制备的14种方法，分别对每种制备方法的优缺点进行了分析，对制备纳米氧化锆粉体的影响因素进行了探讨，提出了制备纳米氧化锆粉体需要进一步研究和解决的理论问题和技术问题。     

聚乙二醇分子量对氧化锆粉体粒径的影响研究

为了控制纳米氧化锆粉体的粒径并降低制备成本,以不同分子量(MW)的聚乙二醇(PEG)作为分散剂,采用辅助溶胶-凝胶法制备纳米氧化锆粉体。利用傅里叶变换红外光谱对凝胶体进行了表征,采用激光粒度仪、X射线衍射仪和扫描电镜对纳米氧化锆粉体进行表征。实验结果证明,不同分子量的PEG具有不同的碳转化率,分解所得的碳颗粒所形成的碳隔离作用有助于控制粉体的团聚,纳米氧化锆的粒径与分散剂的碳转化率成反比。     

化学法制备ZA复合粉体的研究

采用溶胶-凝胶法和共沉淀法两种化学方法制备了氧化铝-氧化锆复合粉体,并对其进行表征:采用激光粒度分析仪测定粉体粒径及粒度分布,X射线衍射仪(XRD)进行矿物相组成分析,扫描电子显微镜(SEM)观察微观下氧化铝与氧化锆的分布情况.结果表明:溶胶-凝胶法制备的粉体相对于共沉淀法制备的粉体粒度较细,四方相氧化锆含量高,而且氧化铝和氧化锆分散较均匀.     

球形四方相氧化锆的水热法合成与表征

以氧氯化锆为原料，尿素为矿化剂，氧化钇为稳定剂，水和乙醇为反应溶剂，结合一步水热的方法，在不添加表面活性剂以及不经过煅烧的前提下，通过改变水热温度、水热时间、醇水比以及氧化钇添加量等条件探究了球形四方相氧化锆的形成机理，制备了结晶性好、粒度分布均匀以及球形度高的四方相氧化锆粉体。     

微波加热制备纳米ZnO粉体及其表征

以硝酸锌和氢氧化钠为原料,三乙醇胺为表面活性剂,采用微波加热沸腾回流,在不同的反应条件下制备出了平均粒径为25～80nm的纳米级ZnO粉体。采用X射线衍射(XRD)、扫描电镜(SEM)及粒度分布仪等测试手段,对产品的物相、形貌和粒度分布进行了表征。实验结果表明,利用微波加热制备出的纳米ZnO粉体结晶性能良好,粒径大小均匀;三乙醇胺的加入,明显地改变了氧化锌的结晶行为,晶体形貌由原来的棒状变为准球形,粒径减小到纳米级。     

Hydrothermal synthesis of nickel ferrite powders,their properties and sintering

NiFe₂O₄ powders were synthesized by co-precipitation with ammonia solution using aqueous solution of NiCl₂ and FeCl₃ followed by hydrothermal treatment of the precipitate. It was found that crystallization in water led to nanometric in size and isometric in shape crystallites, whereas crystallization in sodium hydroxide solution results in particles of well defined walls. Generally, particles crystallized in water were smaller and their particle size distribution was narrower than those crystallized in NaOH solution. Behaviour of the powders under dry compaction and sintering strongly depended on the powder morphology. The powder crystallized in NaOH solution gave compacts of higher density and sintered density of this powder was also higher than that of the powder processed in water.     

SrSn_4P_6O_(24)粉料的合成

本研究的目的在于根据NZP[NaZr2 (PO4) 3]晶体化学特性 ,设计出一新的NZP化合物SrSn4P6 O2 4(SSP) ,为二元及多元NZP热膨胀调整提供新的单元组成 .为此 ,本研究采用固相法、共沉淀法及水热法进行了合成实验 ,并做了XRD ,SEM ,TEM及IR光谱检测 .结果表明 :3种方法都能合成SSP ,其中以共沉淀法合成的物相最纯 ,固相法合成的SSP的X射线衍射强度最大 .粉料的颗粒形貌取决于合成条件及合成方法 ,水热法在使用磷酸作矿化剂时获得了单分布形状为正六边形的颗粒 ,物相为单斜相 .使用水和氢氧化钠为矿化剂时 ,颗粒为近似方形及圆形 ,均为NZP相     

Hydrothermal Synthesis of Cerium(IV) Oxide

CeO₂ powders have been prepared from cerium(III) nitrate, cerium(IV) sulfate, and cerium(IV) ammonium sulfate under hydrothermal conditions at 120° to 200°C for 5 to 40 h. The effects of the starting cerium compounds, hydrothermal treatment temperature, and the concentration of the solutions on the crystal growth of CeO₂ were investigated. CeO₂ powders hydrothermally synthesized at 180°C for 5 h from cerium(IV) salts had very fine particle sizes (30 Å); on the other hand, the powder from the cerium(III) salt had a relatively coarse particle size (160 Å). Although the crystallite size of the powder synthesized from the cerium(IV) compounds depended on the treatment temperature, that from the cerium(III) compound was insensitive to the treatment temperature. The mechanisms for the growth of CeO₂ particles under hydrothermal conditions are discussed.     

The study on the effective factors of hydrothermal synthesis in preparing high quality crystalline α-quartz powders

In this study powders of high quality crystalline α-quartz were prepared by hydrothermal synthesis and parameters related to the preparation of the material were investigated. The degree of face development of the α-quartz crystal depended on the relative growth rates of a particular form that varies considerably with the degree of supersaturation. reaction temperature, concentration of mineralizers, and the amount of seed crystals in the feedstock. In the temperature range of 240–450°C and the pressure range of 100–300 atm, alkali hydroxides and alkali halides such as KOH. NaOH. Na₂CO₃, KF, and NaF were found to be the effective mineralizers. As the concentration of mineralizers increased, the particle size of crystalline α-quartz powders became smaller at lower reaction temperatures The fractional size distribution of synthetic crystal powders depended on the hydrothermal conditions. As the reaction time and the amount of seed crystals increased, the width of particle size distribution became narrower. The weighl mean particle size was in the range of 1 μm to 10 μm. The characterization of the products were carried out using XRD, SEM, PSA, FTIR, and Raman spectrometer.     

锐钛矿型F-TiO2溶胶光催化剂的制备及表征

引言 二氧化钛溶胶光催化剂由于具有粒子颗粒度小、催化活性高、容易固载到基质材料上等优点而受到了广泛的关注.     

SnO_2纳米晶的制备及性能研究

研究了化学沉淀法、柠檬酸法和微波水热法等三种不同制备方法对SnO_2纳米晶粒径的影响,并通过XRD及TEM对其结构进行了表征。结果发现,用微波水热法制得的SnO_2粒径最小,为5～15nm,且分布较均匀。用化学沉淀法制备了Fe、Sb掺杂的纳米晶SnO_2粉末并测定了其电阻,发现Fe掺杂使SnO_2电阻升高、Sb掺杂使电阻下降。     

球磨过程对ZrO_2粉末团聚的影响

本文采用两种不同粒度的工业３ｍｏｌ％Ｙ2Ｏ3－ＺｒＯ2粉为原料,研究了球磨过程对粉末粒度和ＺｒＯ2粉末团聚系数（ｄ50／ｄBET）的影响。实验结果表明：球磨能使大团聚粒子破碎,平均粒径减少,团聚系数降低,粉末粒度更均匀,随着球磨时间的延长,粉末平均粒径细化速度减慢。ＺｒＯ2团聚粒子破碎过程中将发生ｔ－ｍ相变。     

Rapid Formation of Active Mesoporous TiO2 Photocatalysts via Micelle in a Microwave Hydrothermal Process

Rapid formation of active, mesoporous, and crystalline TiO₂ photocatalysts via a novel microwave hydrothermal process is presented. Crystalline anatase mesoporous nanopowders 100–300 nm in size with worm hole-like pore sizes of 3–5 nm were prepared by a modified sol–gel of titanium tetra-isopropoxide, accelerated by a microwave hydrothermal process. The organic surfactant, tetradecylamine, which is used as a self-assembly micelle in the sol–gel and microwave hydrothermal process, enables to harvest crystallized mesoporous anatase nanoparticles with a high-surface area. Mesoporous worm hole-like and crystalline powders with surface areas of 243–622 m²/g are obtained. X-ray diffraction, N₂-adsorption isotherms (Barrett–Joyner–Halenda and Brunauer–Emmet–Teller method), scanning electron microscope, and transmission electron microscope are used to identify the characteristics and morphologies of the powders. It is shown that crystallization by calcination at 400°C/3 h inevitably reduced the surface area, while the microwave hydrothermal process demonstrated a rapid formation of crystalline mesoporous TiO₂ nanopowders with a high-surface area and excellent photocatalytic effects.     

超细BaTiO3粉体制备的研究进展

综合评述了超细酸钡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法和金属有机物热解法和有机盐-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.