Bi Effect on the Microstructure and Dielectric Properties of SrTiO3 Thin Films
Crystalline (Sr1-1.5xBix)TiO3 (SBiT) thin films (0.002 ≤ x ≤ 0.5) were prepared by sol-gel on Pt/TiO2/SiO2/Si substrates. Cubic monophasic SBiT films were obtained for samples with x ≤ 0.167. For films with x ≥ 0.267 a second phase identified as Bi4Ti3O12 was observed. The lattice parameter of SBiT films increases with increasing Bi content, similar to the variation observed in SBiT ceramics. No obviously variation of the grain size with the Bi content was observed. The dielectric constant ε´ at room temperature increases with increasing of Bi concentrations up to x ≤ 0.1. The loss tangent of Bi doped SrTiO3 films is approximately 0.05 and lower than undoped ST films at 10kHz. The higher values of ε´ of Bi doped ST films with x=0.1 and x=0.167 in comparison with undoped films may suppose the appearance of a dielectric anomaly at low temperatures, which will be dependent on the Bi content.
Paula Maria Vilarinho
O. Okhay, V. M.X. Bergano, A. Y. Wu, P. M. Vilarinho, "Bi Effect on the Microstructure and Dielectric Properties of SrTiO3 Thin Films", Materials Science Forum, Vols. 514-516, pp. 245-249, 2006