组分梯度（Ba,Sr）TiO3薄膜的制备工艺研究

Study on preparation process of compositionally graded （Ba,Sr）TiO3 thin films

采用改进的溶胶．凝胶（sol-gel）法在si衬底上制备了组分梯度Ba1-xSrxTiO3（x=0，0．1，0．2，0．3，0．4）（简称BST）薄膜。探讨了不同退火温度对组分梯度BST薄膜晶化的影响，应用X射线衍射（XRD）及原子力显微镜（AFM）分析了薄膜的微观结构。结果表明组分梯度薄膜的最佳制备工艺为600℃预烧5min，700℃退火1．5h，此时薄膜具有完整的钙钛矿相，薄膜表面平整、无裂纹、无孔洞。比较了单组分和组分梯度BST薄膜的微观结构。XRD测试结果显示，组分梯度BST薄膜的衍射峰峰位介于底层和硕层单组分BST薄膜之间，且衍射峰明显宽化；AFM测试结果表明，组分梯度BST薄膜的晶粒明显大于单组分BST薄膜，表面均方根粗糙度（RMS）也大于单组分BST薄膜，这可能是由于组分梯度薄膜较高的预烧温度促进晶粒生长造成的。

Compositionally graded Ba1-xSrxTiO3（x=0,0.1,0.2,0.3,0.4） （BST） were fabricated on Si substrates by a modified sol-gel method. The effect of annealing temperature on crystallization of compositionally graded BST thin films were discussed. The X-ray diffraction （XRD） and atomic force microscopy （AFM） results indicated that the most optimum process parameters of compositionally graded BST films were 600℃ pre-annealed for 5rain and 700℃ annealed for 1.5h. The graded films have uniform and crack-free surface morphology with peroskite structure phase. The microstructure of single composition BST thin film and compositionally graded BST thin films were compared. XRD results showed that the peaks of compositionally graded BST thin films were between the bottom and top single composition BST thin film. The diffraction peaks of compositionally graded were significantly broadened. The results of AFM indicated that the compositionally graded BST thin film has larger grain size than the single composition BST thin film. While, the root mean square （RMS） of compositionally graded BST film was also larger than the single composition BST thin film. This may be due to the higher pre-annealing temperature of compositionally graded BST thin film.