Fabrication of SiO2-doped Ba0.85Sr0.15TiO3 glass-ceramic films and the measurement of their pyroelectric coefficient

SiO2-doped Ba0.85Sr0.15TiO3 (SBST) glass-ceramic (g-c) films with perovskite structure have been prepared on Pt/Ti/SiO2/Si substrates by sol-gel technique. Differential thermal analysis (DTA), X-ray diffraction (XRD) and atomic force microscopy (AFM) are employed to analyze the synthesize process and microstructure of SBST g-c films. The ferroelectricity and crystallization behavior of SBST films are discussed. It is found that the starting synthesize temperature of SBST15 film is larger than that of pure barium strontium titanate (BST) film for about 60 deg. C. The grain sizes decrease and the ferroelectricity of SBST g-c films is degenerated, but their loss tangent and leakage current density decrease with increasing SiO2 contents. The temperature coefficient of dielectric (TCD) and the pyroelectric coefficient γ of the films are measured. The results show that TCD and the pyroelectric coefficient γ of SBST5 film at 20-25 deg. C are, respectively, 4.6% deg. C-1 and 8.1x10-8 C cm-2 K-1, which is about 2/3 value of the pure BST films. BST g-c film with 5 mol% SiO2 dopant is hopeful to be the advanced candidate material for uncooled infrared focal plane arrays (UFPAs) applied at near room temperature