(Pb_(0.5)Sr_(0.5))TiO_3薄膜的表面化学态研究

Structural and surface chemical states of (Pb_(0.5)Sr_(0.5))TiO_3 thin films by sol-gel process

用溶胶-凝胶法制备(Pb0.5Sr0.5)TiO3(简称PST)前驱体溶液,以三水醋酸铅、醋酸锶、钛酸丁酯为原料,乙二醇甲醚、去离子水、乙酰丙酮做溶剂,通过旋涂工艺在Pt/Ti/SiO2/Si(100)基片上沉积PST薄膜。薄膜经320～380℃热分解,再经650℃退火30min,得到晶化好的薄膜样品,X射线衍射结果表明PST薄膜为钙钛矿立方相结构,其晶格常数为a=0.3919nm。用原子力显微镜观测其表面形貌,薄膜平均晶粒尺寸为300nm。用XPS测量了650℃退火PST薄膜样品的表面化学态,结果表明表面富铅,接近表面区域的原子比率Pb∶Sr∶Ti∶O是0.52∶0.50∶1.0∶3.02,接近(Pb0.5Sr0.5)TiO3的理想配比。

Lead strontium titanate （Pb0.5 Sr0.5）TiO3 （abbreviated as PST） thin films were deposited on Pt/Ti/ SiO2/Si（100） substrates by using a sol-gel method with spin-coating processing. The crystalline films were studied by means of X-ray diffraction （XRD） and atom force microscopy （AFM）. The results show that the film was annealed at 650℃ for 30min with perovskite cubic phase, and the lattice parameter a= 0. 3919nm. The chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy （XPS） near the surface. The results show that the extra lead oxides exist in film surfaces. The atomic ratio Pb ： Sr ： Ti ： O in the near-surface region is 0. 52： 0.50 ： 1.00 ： 3.02, which is closer to the stoichiometry of （Pb0.5Sr b0.5）TiO3.