溶胶-凝胶法PLT薄膜的形成与热处理温度关系研究

利用溶胶－凝胶法合成了透明溶胶和白色稳定乳浊液两种前驱体，通过Ｄｉｐ－ｃｏａｔｉｎｇ方法分别利用掺入及不掺入同配方的晶体微粉的这两种前驱体制备了Ｐｈ_０．９Ｌａ_０．１５ＴｉＯ_３ 薄膜，并通过 Ｘ射线衍射（ＸＲＤ）；扫描电子显微镜（ＳＥＭ）和介电常数测试等手段进行了形成特性研究和比较．结果显示，利用白色乳浊液前驱体制备的Ｐｂ_０．９　Ｌa_０．１５ＴｉＯ_３ 薄膜，其最初形成钙钛矿相的温度比利用透明溶胶制备的同样薄膜的温度降低约４０～５０℃；利用透明溶胶前驱体制备的Ｐｂ_０．９Ｌａ_０．１５ＴｉＯ_３薄膜在热处理温度高到约５７５℃时，钙钛矿相的晶格常数相应下降；约在５２５℃热处理时，薄膜居里温度出现在室温附近；较高的热处理温度时，薄膜中形成的钙钛矿相中Ｌａ的固溶度相对较小，反之则Ｌａ的固溶度较高．

Relationship between Phase Formation and Calcination Temperature of Sol-Gel Derived PLT Thin Film

Two kinds of precursors, being transparency and milky in status respectively, were prepared. Thin films of Pb_0.9La_0.15TiO₃ were coated on glass substrates with the two precursors added with or without crystallite nano powders of Pb_0.9La_0.15TiO₃ respectively by dip-coating methods. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and dielectric spectroscopy were respectively used to observe the morphology, phase status and dielectric constant of the films. In conclusion, the initial temperature of forming the perovskite phase of Pb_0.9La_0.15TiO₃ thin film derived from the milky precursor is 40-50℃ lower than that from transparency precursor. On the other hand, crystal lattice of the perovskite phase of the film derived from the transparency precursor decreases while the calcination temperature is in high level of about 550℃ and up. The Curie point is near room temperature when the film is calcined at about 525℃. And the solid solubility of La in the perovskite phase decreases with increasing the calcination temperature of the film, and vice versa.