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Glycothermal Synthesis of Thermodynamically unstable Mixed Oxides

热力学不稳定混合氧化物的糖热合成

基本信息

批准号：
09650922
负责人：
INOUE Masashi
金额：
$ 1.79万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650922/
关键词：
Glycothermal reaction Metastable Phase Mixed Oxide Ultrafaine Particles Solid Solution Surface Energy Crystal Growth Coltoidal Solution 表面積グリコサーマル法希土類欠陥

项目摘要

This research has been carried out show that the glycothermal reaction, which this researcher has developed to synthesis nanocrystals of various metal oxides, can be applied for the synthesis of the metastable metal oxides. In 1997, the reaction mechanisms for the formation of hexagonal LnFeOィイD23ィエD2 by the reaction of iron acetylacetonate with rare earth acetates was examined in detail and the following points were found : (1) Reactivity of the starting material was controlled by the thermal stability of the ligand. (2) Higher reaction temperature increases the instability of hexagonal LnFeOィイD23ィエD2 and therefore increases the solubility of the phase resulting in an increase in the particle size of the product. (3) When the reaction was carried out in the presence of a small amount of garnet crystals, hexagonal LnFeOィイD23ィエD2 was not formed but rare earth iron garnet was formed. It was concluded that the prime factor for the formation of the metastable phase is the thermodynamical i … More nstability of the glycoxide intermediate, which gives large driving force for the formation of the final product. In 1998, the reaction of indium alkoxide with rare earth acetates, the reaction of aluminum isopropoxide with gallium acetylacetonate, and the reaction of titanium alkoxide with tetraethyl silicate were examined. The first reaction yielded the InィイD22ィエD2OィイD23-ィエD2LnィイD22ィエD2OィイD23ィエD2 solid solutions but metastable unidentified phases were also formed. The second reaction afforded large-surface area alumina-gallium oxide solid solutions having a crystal structure of metastable γ-alumina. The last reaction yielded a titania-silica solid solution having the anatase crystal structure. In this reaction, the sold solution with quite a large surface area was obtained by lowering the reaction temperature. During the course of the work mentioned above, this researcher also examined the reaction of cerium metal in 2-ethoxyethanol and found that the reaction afford a transparent colloidal solution of ultrafine ceria particles (2 nm diameter). One of the reason why this reaction afforded ceria having unique properties was that the oxidation of cerium metal gave quite a large driving force to the reaction. Less

研究表明，本研究开发的合成各种金属氧化物纳米晶的糖热反应，可以应用于亚稳态金属氧化物的合成。1997年，作者详细研究了乙酰丙酮铁与稀土醋酸盐反应生成六方相LnFeOィイD23ィエD2的反应机理，发现：(1)原料的反应活性受配体的热稳定性控制。(2)较高的反应温度增加了六方相LnFeO-ィイ-D23-ィエ-D2的不稳定性，从而增加了相的溶解度，导致产物的粒度增大。(3)在有少量石榴石晶体存在的情况下，反应没有生成六方相LnFeOィイD23ィエD2，而生成了稀土铁榴石。结果表明，亚稳相形成的首要因素是热力学i-…糖氧化物中间体更不稳定，这为最终产品的形成提供了很大的推动力。1998年，研究了醇铟与醋酸稀土的反应，异丙醇铝与乙酰丙酮镓的反应，醇钛与硅酸乙酯的反应。第一步反应生成InィイD22ィエD2OィイD23-ィエD2LnィイD22ィエD2OィイD23ィエD2固溶体，但也有亚稳相生成。第二步反应得到了具有亚稳态γ-Al_2O_3晶体结构的大比表面积Al_2O_3-GaO_2固溶体。最后一次反应生成了具有锐钛矿晶体结构的二氧化钛-二氧化硅固溶体。在该反应中，通过降低反应温度，得到了比表面积较大的溶液。在上述工作过程中，本研究人员还研究了金属Ce在2-乙氧基乙醇中的反应，发现该反应提供了直径为2 nm的超细CeO2的透明胶体溶液。这一反应使CeO_2具有独特性质的原因之一是金属CeO_2的氧化为反应提供了相当大的驱动力。较少