Examination of possible high-pressure candidates of SnTiO3: The search for novel ferroelectric materials

Following the recent successful synthesis and characterization of bulk SnTiO3, its energy landscape was studied by means of density functional theory, applying different exchange–correlation and hybrid functionals. Experimentally accessible structure candidates with composition ABX3 were identified by a database search and global exploration approach. Besides the common octahedral coordination of Ti, also fourfold and fivefold coordination spheres emerged to be reasonable structural motifs. Among the predicted high-pressure modifications, the tetragonal perovskite structure turned out to be stable at pressures between 11 GPa and 15 GPa. The possibility of a paraelectric-to-ferroelectric phase transition of the tetragonal perovskite structure was investigated by modeling the phonon spectra and soft mode behavior. Despite substantial long wavelength transverse optical mode softening, the predicted high c/a-ratio in tetragonal perovskite SnTiO3 inhibits the formation of a spontaneous reversible polarization.