E. Ching-prado et al., Raman scattering in the aurivillius-layered ferroelectric SrBi2Ta2O9-Bi3TiNbO9 thin films, INTEGR FERR, 29(1-2), 2000, pp. A33-A41
We have used Raman spectroscopy to investigate thin films of ferroelectric
(SrBi2Ta2O9)(x)(Bi3TiNbO9)(1-x) layered structures and to compare them with
the corresponding bulk materials. Various compositions, with x = 0.0, 0.2,
0.4, 0.6, 0.8, and 1.0, were prepared by metal organic solution deposition
method on Pt/TiO2/SiO2/Si substrates. A topographic micro-Raman study reve
aled very homogeneous films at each composition. The Raman spectrum of x =
0.0 film shows bands around 170, 232, 337, 522, 608, 677 and 832 cm(-1). wh
ich indicates Bi3TiNbO9 formation. The evolution of the Raman bands with th
e cm inclusion of SBT material shows frequency shifts and a broadening of t
he bands due to the differences in mass between Sr acid Bi in the A-sites,
and Ta, Ti, and Nb in the B-sites. A lower degree of crystallization was fo
und in the films compared to the bulk due to the presence of stress in the
films. Strong contributions from defects were also observed in the temperat
ure-dependent Raman spectra.