Hydrothermal Synthesis of Metal Oxide Fine Particles at Supercritical Conditions
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- 作者：Tadafumi Adschiri ; Yukiya Hakuta ; and Kunio Arai
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2000
- 出版时间：December 2000
- 年：2000
- 卷：39
- 期：12
- 页码：4901 - 4907
- 全文大小：273K
- 年卷期：v.39,no.12(December 2000)
- ISSN：1520-5045
文摘
Supercritical water can provide an excellent reaction environment for hydrothermal crystallization of metal oxide particles. Because of the drastic change of properties of water aroundthe critical point, density, dielectric constant, and ionic product, the phase behavior for thesupercritical water-light gas (O2, H2, etc.) system and reaction equilibrium/rate can be variedto synthesize new materials or define particle morphologies. In this work, hydrothermalcrystallization experiments were performed with several types of flow apparatuses that allowconvenient manipulation of variables such as temperature, pressure, and residence time. Theproposed supercritical hydrothermal synthesis method has the following desirable features: (1)ultrafine particles can be produced, (2) morphology of the produced particles can be controlledwith small changes in pressure or temperature, and (3) a reducing or oxidizing atmosphere canbe applied by introducing oxygen, hydrogen, or other gases. An overview of this method is givenfor functional material synthesis of significant industrial interest including barium hexaferritemagnetic particles, YAG/Tb phosphor fine particles, and lithium cobalt fine crystals.