Fabrication and Crystal Structure of Sol-Gel Deposited BST Thin Films with Compositional Gradient

Abstract

In the present research technology of compositionally graded barium strontium titanate Ba 1-x Sr x TiO 3 thin films deposited on stainless steel substrates by sol-gel spin coating followed with thermal annealing at T = 650°C is reported. Results of thermal behavior of the sol-gel derived powders with compositions used for fabrication of graded structure (i.e. with Sr mole fraction x = 0.5, 0.4 and 0.3) are described. X-ray diffraction studies of the phase composition and crystal structure of such complex thin film configuration are given. It was found that gel powders exhibited a large total weight loss of about Δm ≈ 44-47%. Three stages of weight loss took place at temperature ranges: below T ≈ 300°C, at ΔT ≈ 300-500°C and between T = 600°C and T = 800°C. Phase analysis has shown that the dominating phase is Ba 0.67 Sr 0.33 TiO 3 compound while the second phase is Ba 0.7 Sr 0.3 TiO 3 or Ba 0.5 Sr 0.5 TiO 3 for "up-graded" and "down-graded" structure, respectively.