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Microstructure control of functional ceramics ih double oxide system by homogeneous solution methods

均相溶液法控制功能陶瓷ih双氧化物体系的微观结构

基本信息

批准号：
11450249
负责人：
KIKKAWA Shinichi
金额：
$ 2.69万
依托单位：
Hokkaido University (2000-2001)Osaka University (1999)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

Excellent properties of functional ceramics have been attained by forming multinary oxides, Their preparation in soft solution process may lead to new meta-stable layered compounds having several kinds of stacking structural units with different properties. This process can also be applied to their micro-structure control. In the present study, we have developed two kinds of the following new soft solution process.(1) Citric acid was added to the mixed aqueous solution of metal nitrates as its geling agent The firing of the gel at 350℃ lead to combustion synthesis of fine powder of functional ceramics with a diameter of less than 100 nm. This process was applied to transparent conducting (ZnO)_3In_2O_3 and also to barium hex ferrite. Usage of EDTA or acetylacetonate complex was effective to avoid inhomogeniety due to the hydroxide formation of a component. This combustion synthesis was also useful to obtain zirconia coated alumina powder.(2) Microgravity condition was applied during freezing of aqueous solution of mixed metal salts. Dendritic ice was formed in this process. The frozen products were freeze dried in vacuum. Relative x-ray intensity of hh0 lines was enhanced in tetragonal crystal strictures ofZrOCi_2・8 H_2O and AlCl_3 6 H_2O. Liner complex ion units ordered much better under microgravity than in ambient condition. Improved homogeniety was observed on the precipitated metal salts in the dendritic ice in comparison to the salts obtained from the frozen product in ambient condition. The homogeniety was effective to obtain double oxide in high yield.

多元氧化物的形成使功能陶瓷获得了优异的性能，它们的软溶液法制备可能导致新的亚稳层状化合物，这些化合物具有多种不同性质的堆叠结构单元。该工艺也可应用于其微观结构控制。在本研究中，我们开发了以下两种新的软溶液工艺。(1)在金属硝酸盐的混合水溶液中加入柠檬酸作为凝胶剂，在350℃下焙烧，可燃烧合成出粒径小于100 nm的功能陶瓷细粉。该工艺已应用于透明导电（ZnO）_3In_2O_3和钡铁氧体。EDTA或乙酰丙酮络合物的使用有效地避免了由于组分的氢氧化物形成而导致的不均匀性。这种燃烧合成也可用于获得氧化锆包覆的氧化铝粉末。(2)将微重力条件应用于混合金属盐水溶液的冷冻过程。树枝状冰就是在这个过程中形成的。将冷冻产物在真空中冷冻干燥。在ZrOCl_2·8H_2O和AlCl_3·6H_2O的四元晶体结构中，hh0线的相对强度增强。微重力条件下线性复合离子单元的有序性比环境条件下好得多。与在环境条件下从冷冻产品获得的盐相比，在树枝状冰中沉淀的金属盐上观察到改进的均匀性。均匀性是获得高产率双氧化物的有效途径。