Hydrothermal synthesis of novel alpha alumina nano-materials with controlled morphologies and high thermal stabilities

Following a strong demand for novel alpha-Al(2)O(3) nano-materials with unique properties, both pure and doped nano-sheets, nano-needles, and nanosized equiaxed particles (reference) of 100% phase-pure alpha-Al(2)O(3), were synthesized at 430-450 degrees C under 10.3 MPa pressure by the hydrothermal treatment of boehmite powder (gamma-AlOOH) in the presence of alpha-Al(2)O(3) seeds and 1 10% morphology modifiers. SiO(2) and H(3)BO(3) were used as morphology modifiers to produce phase pure alpha-Al(2)O(3) nano-sheets and nano-needles, respectively, that exhibited strong crystallographic c- and a-faceting and BET surface areas up to 40 m(2) g(-1) stable above 1000 degrees C. A mesocrystal growth mechanism of the alpha-Al(2)O(3) nano-particles was observed. Unprecedented flexibility to control the sizes and morphologies of alpha-Al(2)O(3) enabled fabrication of 90% porous ceramics with unique pore geometries and pore volumes up to 1.5 cm(3) g(-1). These novel alpha-Al(2)O(3) nano-materials can be useful in a variety of catalytic applications, nano-filtration, chemical-mechanical planarization, composites, etc.