采用有机金属沉积法(MOD)制备了Bi4Ti3O12(BIT)和Bi3.25La0.75Ti3O12(BLT)前驱体溶液,分别在单晶硅基片上制备了BIT和BLT铁电薄膜。前驱体溶液的干凝胶粉体和铁电薄膜分别用红外光谱(FTIR)、拉曼光谱和环境扫描电镜(ESEM)进行了表征。结果表明600℃时晶粒实现了由焦绿石相向类钙钛矿相结构的完全转变;温度升高,晶粒尺寸增大,薄膜结晶效果得到改善;引入镧使Ti—O和Bi—O键吸收峰位置向低波数频移,高温时频移率较大;500℃热处理时,干凝胶中乙二醇甲醚、乙酰丙酮完全分解,温度超过600℃后,残留的水及硝酸根离子挥发或分解。
Bi4Ti3O12 (BIT) and Bi3.25 La0.75Ti3O12 (BLT) precursor solutions were prepared using metal-organic deposition method. BIT and BLT ferroelectric thin films were grown on the polished single crystal Si substrates. Dry gel powders of precursor solution and ferroelectric thin films were analyzed by FTIR spectrum, Raman spectrum and ESEM. The results show that crystal structure was translated completely from pyrochlore to perovskite at about 600 ℃. The dimension of crystal particles enlarges with the increase in annealing temperature. The peaks of Ti--O and Bi--O bond shift to lower wavenumbers because of introducing La into Bi4 Ti3O12, and this phenomenon becomes distinct with rising temperature. When the heat treatment temperature is 500 ℃, CH3OCH2 CH2 OH and CH3COCH2 COCH3 in dry gel completely decompose and volatilize. Water molecules volatilize and nitrate ions decompose completely over 600℃.