Growth Mechanism of Monodispersed ZrO2 Particles

Monodispersed ZrO₂ seed particles which were prepared by hydrolysis of zirconium alkoxide solutions were allowed to grow by further addition of zirconium alkoxide and water under conditions in which new particles do not nucleate and grow. The particle growth mechanism is presumed to be a surface reaction in which the rate-determining step is a first-order polynuclearlayer growth mechanism. With this method of powder preparation, it is possible to precisely control the particle size, and it may be useful for applications in ceramic processing.     

Hydrolytic Condensation of Tin(IV) Alkoxide Compounds to Form Particles with Well-Defined Morphology

The sol-gel-type condensation of tin(IV) ethoxide [Sn(OEt)₄] n (where OEt is ethoxide) under basic conditions produced spherical, submicrometer-sized tin(IV) oxide (cassiterite) particles. Transmission electron microscopy and powder X-ray diffraction data indicated that the grain size was approximately 20 to 30 Å (2 to 3 nm). The mixed-metal alkoxide compound [ZnSn(OEt)₆] was hydrolyzed under analogous conditions to give either spherical or octahedral submicrometer-sized crystalline particles of ZnSn(OH)₆ depending on the solvents used. These data demonstrated that the stoichiometry of the mixed-metal alkoxide precursor was retained during condensation. Thermal treatment of ZnSn(OH)₆ resulted in crystallization of ZnSnO₃ at approximately 676°C. At neutral pH, hydrolysis of [ZnSn(OEt)₆] resulted in formation of a high surface area (261 m²/g) amorphous powder.     

NaOH、甘油的水溶液浸出三氧化二锑的机理研究

NaOH、甘油或木糖醇的水溶液浸出锑氧粉得到双金属醇盐 ,溶液在一定的碱性条件下能保持稳定 ;本文对NaOH、甘油的水溶液浸出三氧化二锑生成甘油亚锑酸钠的机理及其稳定性作了一系列的研究     

聚乙烯催化剂用烷氧基镁载体的研究进展

基于烷氧基镁载体的Ziegler-Natta聚乙烯催化剂具有活性高、氢调性能好等优点,是目前聚烯烃工业中的研究热点.介绍了烷氧基镁载体的发展进程,综述了烷氧基镁载体的制备及改进方法,分析了烷氧基镁载体在催化剂制备过程中的作用,并对开发适用于乙烯聚合的烷氧基镁载体提出了展望.     

烷氧混合稀土掺杂改性对聚苯乙烯抗冲性能的影响

通过原位本体聚合制备三种不同链长的烷氧基(异丙氧基、异丁氧基、异辛氧基)混合稀土掺杂的改性聚苯乙烯。研究了烷氧稀土改性聚苯乙烯的动态力学性能，并潮定其冲击强度。结果表明，三种烷氧稀土掺杂的改性聚苯乙烯均在低温-80℃左右出现一个大的β转变峰，且低温损耗模量峰的模量均比PS高一个数量级，表明改性聚苯乙烯具有较好的抗冲性能，其中三异丁氧基稀土掺杂的聚苯乙烯的冲击强度最高。     

Formation and growth mechanism of porous,amorphous, and fine particles prepared by chemical vapor deposition. Titania from titanium tetraisopropoxide

The formation and growth mechanism of porous, amorphous, and fine particles were investigated. TiO₂ particles were produced in a tubular flow reactor by a chemical vapor deposition technique using titanium tetraisopropoxide as a starting material at low temperatures (573-973 K) and atmospheric pressure. Prepared particles were of submicron size and had large surface area (as large as 270 × 10³ m²/kg). According to the proposed mechanism, reactions begin on the reactor wall and then the primary particles form in the gas phase by chemical reactions. The primary particles collide, coalesce with each other and grow. However, significant experimental deviations from the Brownian collision and coalescence theory imply that other processes, such as the surface reactions on the particle, play an important role in the growth, in addition to coalescence. Intraparticle reactions decreased the surface area by filling the pores.     

不同烷氧基钬掺杂增韧聚苯乙烯的研究

采用四种烷氧基钬化合物掺杂和苯乙烯本体聚合制备了不同掺钬聚苯乙烯材料，XPS测试表明掺杂聚苯乙烯中存在着钬离子和聚苯乙烯大分子苯环π电子之间存在配位作用。SEM照片和DMTA的数据探讨烷氧基钬增韧聚苯乙烯的作用机理，并讨论不同链长的烷氧基对聚苯乙炮的增韧作用影响，表明掺钬聚苯乙烯的冲击强度显著提高，表明烷氧基钬对聚苯乙烯有明显的增韧改性作用。     

低温化学气相合成氧化钛超细粒子

氧化钛超细粒子具有很高的化学活性、良好的耐侯性和耐化学腐蚀性等,可。良的光催化剂、催化剂载体或吸附剂,也是功能陶瓷、高级油漆及涂料的主要尿 合成方法有液相法和气相法。液相法中最有代表性的是金属醇盐水解法［,’］。气。TIC14氧化怯L’】该法原料易得,产品粒度细,单分散性好,但反应温度高且副产品作者将金属醇盐水解反应移植至气相,利用亚微米级的金属醇盐气溶胶同水蒸气。     

溶胶-凝胶法制备BAS玻璃陶瓷

采用预先部分水解的正硅酸乙酯、正硅酸乙酯与乙醇钡之间的中和反应生成复合醇盐以及选择合适的醇盐混合次序等方法,在加水量为水／ 醇盐（ 摩尔比） ＝ ６ ～８ 的条件下,成功合成出均匀透明的ＢＡＳ（ＢａＯＡｌ２Ｏ３ＳｉＯ２） 凝胶．在干燥、焙烧与致密化处理后,获得具有８０ ％ 以上架状与纯架状分子网络结构、网络断键程度小于１２ ％ 的ＢＡＳ凝胶玻璃．其粉体经热压与热处理后,获得以单斜钡长石为主晶相的ＢＡＳ玻璃陶瓷,其室温的σｆ ＝ １３４ ＭＰａ,１２５０ ℃的σｆ ＝ １００ ＭＰａ,α＝ ４－５×１０ － ６／ ℃,有可能作为１ ２００ ℃以上工作的复合材料基体材料．