Preparation and Characterization of Macroporous α‐Alumina

Abstract

α‐Al2O3 powders with three‐dimensionally ordered or randomly positioned macropores were synthesized by templating with poly(methyl methacrylate) colloidal crystals. Aluminum nitrate was precipitated with ammonium hydroxide within the interstices of the template; calcination removed the polymer and converted the inorganic precursors into a macroporous skeleton of α‐Al2O3. Subsequent calcination at higher temperatures and hot stage transmission electron microscopy experiments were performed to study sintering effects on the product morphology. These materials combine the thermal and chemical stability of corundum with a very open structure of uniform macropores that can permit facile transport of guest molecules in potential catalysis, filtration, and sensing applications.

Macroporous ZrO2 ceramics prepared from colloidally stable nanoparticles building blocks and organic templates

“…Furthermore, the three-dimensional pore network can be seen through the porous layers. The wall framework was composed of nano-ZrO 2 particles up to 1000 • C. The nano-ZrO 2 particles were slightly sintered at 1000 • C and fully sintered at 1400 • C. In addition, bulk ZrO 2 pellets prepared from the same ZrO 2 suspension had a relative density of 98% after sintering at 1400 • C. Although the pores lost their spherical shapes and became irregular after firing at 1400 • C, which is due to sintering and grain growth, the pore distribution was still uniform and the ZrO 2 wall framework was kept rather than collapsed as reported in other studies, wherein the colloidal crystal template method was applied [18]. This can be attributed to the narrow particle size distribution of nano-ZrO 2 powders and the uniform and high surface area coating of PS particles.…”

High temperature behavior of monodisperse porosity in alumina films

“…Detailed modelling and experimental work by Zhao and Harmer has studied the grain growth and evolution of random, large, templated pores (1-8 m) in bulk alumina compacts [20][21][22]. The preparation and thermal stability of 3DOM alumina and yttria-stabilized zirconia have been investigated by Sokolov et al [23] and Lashtabeg et al [24,25], respectively, using pore sizes (450-1000 nm) in the range of optical interest. Sokolov et al noted that structural degradation accompanied grain growth and that mass transport occurred from the struts to the nodes in such periodic structures [23].…”

“…The preparation and thermal stability of 3DOM alumina and yttria-stabilized zirconia have been investigated by Sokolov et al [23] and Lashtabeg et al [24,25], respectively, using pore sizes (450-1000 nm) in the range of optical interest. Sokolov et al noted that structural degradation accompanied grain growth and that mass transport occurred from the struts to the nodes in such periodic structures [23]. Further understanding is still required about the behavior of individual pores and the consequences of bring pores into closer proximity with increasing pore fractions in ordered and disordered structures.…”

Effect of heating rate on the fabrication of tunable ordered macroporous structures mediated by colloidal crystal template

“…Although calcination is the conventional method for the preparation of inorganic porous materials templated with organic microspheres, the different calcinations condition will result in the different morphology of ceramic. Sokolov et al discussed the process of calcinations at different higher temperatures for ␣-alumina in order to study sintering effects on the product morphology [25]. Moreover, they described that different calcination temperatures will result in the different ceramic macroporous structures.…”