The n = 8 member of the Aurivillius complex oxide superlattice series of phases, Sr5Bi4Ti8O27, was synthesized by pulsed-laser deposition on (001) SrTiO3 single-crystal substrates. This phase, with a c-axis lattice parameter of 7.25 ± 0.036 nm, and its purity were confirmed by x-ray diffraction and transmission electron microscopy. The film is observed to be single phase and free of intergrowths of other-n members of the series. Using spectroscopic ellipsometry, Sr5Bi4Ti8O27 was determined to exhibit an indirect band gap of 3.53 eV at room temperature.
This assumption seems reasonable based on the previously observed downward trend of the paraelectric-to-ferroelectric phase transition temperature (TC) with increasing n of other members of this (Bi2O2)(Sr,Bi)n−1TinO3n+1) = Bi4Ti3O12·(SrTiO3)n−3 Aurivillius series of phases.31 A TC of 141 K can be extrapolated from that data for the n = 8 Sr5Bi4Ti8O27 phase.