화학공학소재연구정보센터
Korean Chemical Engineering Research, Vol.45, No.5, 448-454, October, 2007
BaTiO3 미세 분말의 수열합성 및 특성분석
Hydrothermal Synthesis and Characterization of BaTiO3 Fine Powders
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초록
미세 BaTiO3 분말의 합성을 위해 함수 티타니아와 수산화바륨을 원료로 수열합성 실험을 수행하여, 반응시간, 온도, 농도 변화에 따른 전화율, 결정구조 및 생성 분말의 물성을 조사하였다. 전화율에 미치는 영향은 시간 <온도 <농도 순이었으며, 2.0 M의 원료를 180 ℃에서 2 h 수열합성 시킬 때 최대 전화율을 99.5%를 얻을 수 있었다. 낮은 농도(0.25 M)에서는 고온에서도 미반응 BaCO3와 미반응 TiO2 생성을 피할 수 없었으며, 이 미반응 물질들은 고온에서 BaTi2O5를 생성시켜 불순물로 존재하였다. 농도를 높일수록 합성 BaTiO3 분말의 크기는 작아졌으며, 분말의 Ba/Ti 비도 1에 접근하였다. 2.0M 이상의 농도에서는 180 ℃, 2 h 반응에서 Ba/Ti 비는 1±0.005 이였다.
Hydrothermal synthesis was conducted with starting material as Barium hydroxide and hydrous titania (TiO2·xH2O) to obtain barium titanate fine Powder. The conversion, crystal structure and properties of as-prepared powder were investigated according to reaction temperature, time and concentration. The effect of variables on conversion was in order of time < temperature < concentration and the maximum conversion reached to 99.5% in the case of hydrothermal synthesis at 180 ℃ for 2 h with 2.0 M reactant concentration. At low concentration such as 0.25 M, formation of unreacted BaCO3 and TiO2 was not inevitable at even high reaction temperature and these components converted into BaTi2O5 at high temperature and remained as impurity. As concentration of reactant increased, the size of as-synthesized BaTiO3 powder deceased and Ba/Ti molar ratio approached into 1, showing Ba/Ti ratio of 1±0.005 for reaction at 180 ℃ for 2 h with 2.0 M concentration.
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