High-temperature X-ray diffraction and spectroscopic studies of some Aurivillius phases

The compounds Bi2MO6 (m = 1), Bi2WO6 (m = 1), Bi3NbTiO9 (m = 2), Bi4Ti3O12 (m = 3) and CaBi4Ti4O15 (m = 4) (Aurivillius phases with the general formula A(m-1)Bi(2)BmO(3m+3)) have been synthesized by solid state reaction method. Using the high-temperature X-ray diffraction, the phase transition and melting temperatures have been determined for these compounds and their thermal expansion coefficients have been calculated. It has been established that composition and structure of Aurivillius phases have significant influence on the Curie temperature. We have also measured room temperature Raman and infrared spectra, and all observed bands have been assigned to respective motions of atoms in the unit cell. The spectra of the synthesized Auriviliius phases are in good agreement with reported in literature results of the lattice dynamics calculations. We also compare and discuss how the spectra change with increasing thickness of the perovskite-like layer. (C) 2017 Elsevier B.V. All rights reserved.