gibbsite (三水鋁石)一直為工業上產氧化鋁的重要原料，其來源豐富價格低廉。但一般由市面上得到的 gibbsite粒體較大，經煆燒後即使進行研磨也難獲得奈米級 alpha-Al2O3粉末。此一認知，是為市場上還無以gibbsite生產奈米級 alpha-Al2O3粉末之原因。本研究以 gibbsite為前導物，觀察 kappa- → alpha-Al2O3 相轉換時 kappa-及 alpha-Al2O3 晶粒成長行為與粉體發育變化的情形，探討是否有以 gibbsite 產得奈米 alpha-Al2O3粉末之可能。研究發現由 gibbsite 相變而來的 kappa- Al2O3 晶粒有成長為條狀的特性並在 c軸截面徑存在相變臨界晶徑~ 40 nm。而初生的 alpha-Al2O3 晶粒形態與 kappa-Al2O3相似並快速聚合成長~ 60 nm同時呈方向性成長為平行條狀結構。爾後 alpha-Al2O3 才發生蠕蟲狀結構。另外，相變過程中 kappa-及 alpha-Al2O3均呈現gibbsite的假型，因此 alpha-Al2O3侷限在假型粒體內發生蠕蟲狀結構並不影響原始粒徑分佈。由實驗結果評估：如有奈米級之 gibbsite即可生產奈米 alpha-Al2O3粉末，且可能由此發展條狀 alpha-Al2O3粉末。

　　Gibbsite is clearly the most important raw materials for preparing alumina powders in the industry, because of the abundant content and low price. Alumina powders can be obtained by calcining gibbsite. But particle size of gibbsite-derived alpha-Al2O3 is always too coarse to attain nano-scale alumina powders even through extremely grinding.
This present work try to utilize gibbsite as a precursor to investigate the transformation of kappa- → alpha -Al2O3, and observe the growth characteristic of kappa-and alpha -Al2O3 crystallites and the crystallites habit evolution during kappa- → alpha -Al2O3 phase transformation. It was found gibbsite-derived kappa- Al2O3 exist wicker-like crystallites whose cross-sectional diameters of c axis have critical size ~ 40 nm.
　　The morphology of alpha-Al2O3 crystallite was the same with kappa-Al2O3 crystallite. It was noted that the crystallite growth of alpha-Al2O3 was carried out until cross-sectional diameter of that grew to ~ 60 nm and formed parallel structure. Thereafter, finger-growth of alpha-Al2O3 occurred. The entire process of transfor-mation showed the pseudomorph of kappa- and alpha-Al2O3 after gibbsite. Therefore, finger-growth of alpha-Al2O3 took place in gibbsite’s particle. And the particle size distributions of various alpha-Al2O3 content samples almost unchanged.
　　In conclusion, the results indicated that the possibility of producing nano-scale alumina powders was based on the nano-scale gibbsite particles, and the wicker-like alpha- Al2O3 powders can be developed by wicker-like kappa-Al2O3 crystallites.

1. T. G. Peason, The Chemical Background of the Aluminum Industry, Monograph of the Royal Institute of Chemistry, London, 1995.
2. W. Siegel, S. Ramasamy, H. Hahn, Z. Ti, T. Lu, and R. Gronsky, “Synthesis, Characterization, and Properties of Nanophase TiO2,” J. Mater. Res., 3, 1367, 1988.
3. 溫惠玲，由Boehmite製得之氧化鋁粉末的theta- →alpha-Al2O3 相轉換，國立成功大學資源工程研究所，博士論文，中華民國89年1月。
4. S. Vuorinen and L. Karlsson, “Phase Transformation in Chemically Vapour-Deposited kappa-alumina,” Thin Solid Films, 214, 132, 1992.
5. I. Levin, D. Brandon, “Metastable Alumina Polymorphs：Crystal Structures and Transition Sequences,” J. Am. Ceram. Soc., 81, 1995, 1998.
6. R. B. Bagwell, G. L. Messing, and P. R. Howell, ”The Formation of alpha-Al2O3 From theta-Al2O3：The Relevance of a ’Critical Size’ and : Diffusional Nucleation or ’Synchro-Shear’? ,” J. Mater. Sci., 36, 1833, 2001.
7. C. S. John, N. C. M. Alam, and G. R. Hays, “Characterization of Transitional Alumina by ‘Solid-State Magic Angle Spinning Aluminium NMR,” Appl. Catal., 6, 341, 1983.
8. G. W. Brindley and J. O. Choe, “The Reaction Series, Gibbsite→Chi Alumina→Kappa Alumina →Corundum,” The Am. Mineral., 46, 771, 1961.
9. T. Sato, “Hydrothermal Reaction of Alumina Trihydrate,” J. Appl. Chem.,
10, 414, 1960.
10. G. Yamaguchi and K. Sakamoto, “Hydrothermal Reaction of Aluminum Trihydroxides,” B. Chem. Soc. Jpn., 32, 696, 1959.
11. R. Naumann, K. Kohnke, J. Paulik, and F. Paulik, “Kinetics and Mechanism of the Dehydration of Hydrargillites. Part II,” Thermochim. Acta, 64, 12, 1983.
12. 黃啟祥、林江財，陶瓷技術手冊(下)，P. 683，中華民國產業科技發展協進會，與中華民國粉末冶金協會出版。中華民國83年7月。
13. K. Wefers, “Nomenclature, Preparation, and Properties of Aluminum Oxides, Oxide Hydroxides, and Trihydroxides,” in Alumina Chemicals, L. D. Hart Ed., Am. Ceram. Soc., Ohio, 1990.
14. B. Clippens and J. J. Steggerda, “Active Alumina” in Physical and Chemical Aspects of Adsorbents and Catalysts, B. GLinsen Ed., Academic Press, New York, 171, 1970.
15. J. Rouquerol, F. Rouquerol, and M. Ganteaume, “Thermal Decomposition of Gibbsite Under Low Pressures I. Formation of the Boehmitic Phase,” J. Catal., 36, 99, 1975.
16. J. Rouquerol, F. Rouquerol, and M. Ganteaume, “Thermal Decomposition of Gibbsite Under Low Pressures II. Formation of Microporous Alumina,” J. Catal., 57, 222, 1979.
17. K. Wefers and G. M. Bell, Oxides and Hydroxides of Aluminum, Alcoa Research Lab., Technical paper No.19, 1972.
18. H. C. Stumpf, A. S. Russel, J. W. Newsome, and C. M. Tucker, “Thermal
Transformations of Aluminas and Their Hydrates,” J. Phys. Chem., 57,
946, 1953.

19. P. Liu and J. Skogsmo, “Space-Group Determination and Structure Model for kappa-Al2O3 by Convergent-Beam Electron Diffraction(CBED),” Acta Cryst. B47, 425, 1991.
20. H. L. Gross and W. Mader, “On the Crystal Structure of -Alumina,” Chem. Commun., 55, 1997.
21. M. Halvarsson, V. Langer, and S. Vuorinen, “X-Ray Powder Diffraction Data for kappa-Al2O3,” Powder Diffraction, 14, 61, 1999.
22. Y. Yourdshahyan, C. Ruberto, M. Halvarsson, L. Bengtsson, V. Langer, and B. I. Lundqvist, “Theoretical Structure Determination of a Complex Material: kappa-Al2O3,” J. Am. Ceram. Soc., 82, 1365, 1999.
23. Y. Chaing, D. P. Birnie Ⅲ, and W. D. Kingery, Physical Ceramics – Principles for Ceramic Science and Engineering, Wiley, New York, 1997.
24. 余樹楨，晶體之結構與性質，國立編譯館主編，中華民國78年10月。
25. A. Putnis and J. D. C. McConnell, Principles of Mineral Behaviour, Elsevier, New York, 1980.
26. A. Putnis, Introduction to Mineral Sciences, Cambridge University
Press, New York, 1992.
27. W. D. Kingery, H. K. Bowen, and D. R. Uhlmann, Introduction to Ceramics, Wiley, Singapore, 1991.
28. F. W. Dynys and J. W. Halloran, “Alpha Alumina Formation in Alum-
Derived Gamma Alumina,” J. Am. Ceram. Soc., 65, 442, 1982.
29. J. R. Wynnyckyj and C. G. Morris, “A Shear-type Allotropic Transfor-
mation in Alumina,” Metallurgical transactions B, 16B, 345, 1985.
30. L. S. D. Glasser, F. P. Glasser, and H. F. W. Taylor, “Topotactic Reactions in Inorganic Oxy-Compounds,” Quart Rev. Chem. Soc., 16, 343, 1962.
31. G. W. Brindley, “Crystallographic Aspects of Some Decomposition and Recrystallization Reactions,” Progr. Ceram. Sci., 3, 1, 1963.
32. C. Klein and C. S. Hurlbut, Jr., Manual of Mineralogy, Wiley, New York, 1993.
33. H. S. Santos, P. K. Kiyohara, and P. S. Santos, “Pseudomorphic Transformations of Euhedral Crystals of -AlOOH into Aluminas,”
Ceram. Int., 20, 175, 1994.
34. S. J. Wilson, “Phase Transformations and Development of Microstructure in Boehmite-Derived Transition Aluminas,” Proc. Br. Ceram. Soc., 28,
281, 1979.
35. 許宇禪，微粒 theta- 與 alpha-Al2O3 混合粉末的熱反應，國立成功大學資源工程研究所碩士論文，中華民國90年7月。