Al(NH_4)CO_3(OH)_2針状微結晶の生成と熱分解

概要

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In order to prepare acicular particles of Al(NH4)CO3(OH)2 (AACH), ammonium alum (AA) and NH4HCO3 (AHC) solutions were mixed at room temperature, and the precipitate was aged in the mother liquor at 60°-120°C in a closed vessel. Effects of ageing conditions on kind of products and their shape and size were investigated. AACH was formed with an excessive amount of AHC over the stoichiometry. Insufficient amounts of AHC produced boehmite. The AACH particles were single crystalline and acicular or lath-like, and long and short axes corresponded to crystallographic c and a axes, respectively. The length of particles was increased by the addition of acid solution such as H2SO4, HCl and HNO3 to the mother liquor in which the precipitates were aged. The AACH particles seemed to be formed from the reaction of amorphous substances, which formed at room temperature, with the ageing solution during ageing at temperatures of 60°-120°C. Gamma-Al2O3 particles obtained by thermal decomposition of AACH particles at 1000°C possessed acicular shape of the parent crystals.
社団法人日本セラミックス協会の論文
1987-05-01