Optimum synthetic conditions of ammonium aluminum carbonate hydroxide (AACH) as starting material for α-alumina fine powders

Koichi Hayashi, Seiji Toyoda, Kunihiko Nakashima, Kenji Morinaga

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Abstract

Ammonium aluminum carbonate hydroxide (AACH) as starting material to obtain α-alumina fine powders was synthesized between aqueous solutions of ammonium hydrogen carbonate (AHC) and ammonium alum (AA). The effects of pH of the AHC aqueous solution and reaction temperature on the formation of AACH are discussed. Three products, amorphous aluminum hydroxide, pseudoboehmite (= low crystalline boehmite) and AACH were formed depending on pH. AACH was mainly formed in alkaline aqueous solutions. Crystallite size of AACH decreased with increasing concentrations of ionic species [NH4+]·[AlO(OH)2-]· [HCO3-] and decreasing reaction temperature. Homogeneous spherical α-alumina particles with a particle size of 0.2 μm were obtained by firing at 1050°C for 6h from the AACH with a crystallite size of 50 angstrom synthesized at a pH of 10.0 at 5°C.

Original languageEnglish
Pages (from-to)444-449
Number of pages6
JournalNippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
Volume98
Issue number5
Publication statusPublished - Jan 1 1990

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All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry

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