The preparation of PbTiO3 powder containing La and Mn was carried out using the oxide as the starting material by hydrothermal method. When the x value corresponding to La substitution was 0.01 in 0.99(Pb(1-x)La(2x/3)TiO3)+0.01MnO2, a single phase structure of the PbTiO3 powder was synthesized. The optimum conditions for preparation of the powder were as follow: 8 M KOH for hydrothermal solvent, reaction temperature of 270 ℃, and running time of 24 h. It was found that the morphology of the synthesized powders were spherical particles with and average size of 70 nm and the specific surface area of 5.5 ㎡/g. The cell parameters of the powder was found to be a=3.78 Å, c=4.01 Å, and cell volume 57.30 Å(3), and they were smaller than those of the pure PbTiO3 powder. However, the cell ratio (c/a) of the powder was the same as the theoretical ratio of c/a=1.06. It was found that the phase transition temperature(T(c)) of the La, Mn-substituted powders was 400 ℃.

산화물을 출발물질로 하여 수열합성법에 의하여 PbTiO3에 La, Mn이 치환된 분말을 합성하고 이를 평가하였다. 0.99(Pb(1-x)La(2x/3)TiO3)+0.01MnO2 조성식으로부터 La의 치환량이 x=0.01인 조성에서 미반응물이 존재하지 않은 단일상의 분말이 합성되었으며, 최적의 수열 반응조건은 수열 용매; 8M-KOH, 반응온도; 270 ℃, 유지시간;24 h임을 알 수 있었다. 치환량이 x=0.01인 합성 분말은 평균 입경이 70 nm로 구형의 입자가 비교적 균일하게 분포되어 있으며, 비표면적은 5.5 ㎡/g을 나타냈다. 격자 상수는 a=3.78 Å, c=4.01 Å와 cell volume 57.30 Å(3)로 고용된 이온의 반경차에 의하여 PbTiO3보다 감소되었으나 정방 정축비(c/a)는 PbTiO3의 이론적 정방 정축비 c/a=1.06와 일치하였다. La, Mn이 치환된 합성 분말의 상전이 온도(T(c))는 400 ℃로 나타났다.