Abstract
The dielectric and thermal properties of Bi (bismuth)-layered perovskite SrBi2Ta2O9(SBT) are discussed in comparison with ferroelectric thin BaTiO3films. Although these two perovskites exhibit quite a different nature, the dielectric properties of BaTiO3thin film are similar to those in bulk SBT. The dielectric properties and pseudo-two-dimensional structure between SBT and thin film suggest that the bulk layered ferroelectric SBT is a good model of ultra-thin ferroelectric film with two perovskite layers, free from any misfit lattice strain with substrate and surface charge at the interface with electrodes. Based on the mechanism of ferroelectric phase transition of SBT, it seems plausible that the ferroelectric interaction is still prominent but shows a crossover from ferroelectric to antiferroelectric interaction in perovskite ultra-thin films along the tetragonal axis.
Highlights
Barium titanate (BaTiO3) is a well-known ferroelectric with perovskite structure, which has been considered to be a prototype for many oxide ferroelectrics
According to the calculations of local field by Luttinger and Tisza [48], the strong ferroelectric interaction between Ti ion and O ions appears along the tetragonal c axis
The strongly correlated -O-Ti-O-Ti-O- chain plays an important role for the appearance of ferroelectricity in bulk BaTiO3 [26], the -O-Ta-O-Ta-O- chain along the pseudo-tetragonal c axis is interrupted by the existence of semiconductor Bi2O2 layers in SBT
Summary
Barium titanate (BaTiO3) is a well-known ferroelectric with perovskite structure, which has been considered to be a prototype for many oxide ferroelectrics. SBT undergoes a ferroelectric phase transition at 608 K, while the dielectric anomaly and anomalous specific heat are small in comparison with BaTiO3 This similarity of crystal structures and dielectric properties between BaTiO3 thin films and layered perovskite SBT shows that both materials have a common mechanism resulted in dielectric nature as discussed . It suggests that SBT may be a good model for an ideal ferroelectric ultra-thin. We will discuss the ferroelectric nature and stability in ultra-thin films on the basis of ferroelectric properties of Bi-layered perovskites
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