engleski

Barium titanate thin films deposition by spray pyrolysis

Barium titanate (BaTiO3) is emerging as a promising material due to the merits of high dielectric constant, low leakage current and excellent piezoelectric, large electro-optic coefficients and ferroelectric properties. Like in other electronic ceramic materials, the electrical properties of BaTiO3 are closely linked to its microstructural features, such as porosity and grain size. For optimal properties, it is desirable to have a homogeneous microstructure. In principle, BaTiO3 ceramics with a dense structure and fine grains have very good dielectric properties. The BaTiO3 thin films with perovskite structure are of particular interest for electronic device applications due to their useful ferroelectric properties. Perovskite-type BaTiO3 was recently tested as a pure phase porous film electrode in dye- sensitized solar cells (DSSC) and as a TiO2/BaTiO3 composite electrode and showed better efficiency than a solar cell with the pure TiO2 electrode. BaTiO3 is an n-type semiconductor, and its band-gap is equal or more than that of TiO2. Thus, DSSC using these perovskite-type semiconductors may exhibit higher VOC than DSSC using TiO2, although the band tuning among electrode, dye and electrolyte is necessary. There are various chemical methods for BaTiO3 preparation co- precipitation, alkoxide hydrolysis, metal- organic processing and hydrothermal treatment. In the form of thin films BaTiO3 were also deposited by RF magnetron sputtering, laser ablation, metal-organic chemical vapour deposition (MOCVD), sol-gel processing and spray pyrolysis. Among the listed deposition techniques, the spray pyrolysis method is widely used to grow complex, multilayered thin films because of its ability to preserve the target stoichiometry to prepare thin films by layer-by-layer growth. In comparison with other deposition techniques, spray pyrolysis has several advantages, such as high purity, excellent control of chemical uniformity and stoichiometry in multi-component systems. The other advantage of the spray pyrolysis method is that it can be adapted easily for the production of large-area thin films. In this work, we will present results of structural analysis of BaTiO3 thin films by spray pyrolysis. Deposition parameters were optimized to get a very thin homogeneous BaTiO3 layer. Precursor solution based on barium acetate [(CH3COO)2Ba] and titanium tetraisopropoxide [C12H28O4Ti] were used for spray pyrolysis experiments. Structural properties of the obtained layer were examined by XRD, Raman spectroscopy and Scanning Electron Microscopy. Acknowledgements: This work has been supported in part by Croatian Science Foundation under the project IP2014-09-9419 and STSM TO-BE COST action. References: [Li2014] 1 Y. Li, C. Wang, Z. Yao, H.-K. Kim, and N.-Y. Kim, Nanoscale Research Letters 9, 530 (2014). [Kumbhar2015] S.S. Kumbhar, M.A. Mahadik, P.K. Chougule, V.S. Mohite, Y.M. Hunge, K.Y. Rajpure, A.V. Moholkar, and C.H. Bhosale, Materials Science- Poland 33, (2015). [Okamoto2014] Y. Okamoto and Y. Suzuki, Journal of the Ceramic Society of Japan 122, 728 (2014).

barium titanate ; thin films ; spray pyrolysis

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