Improved ferroelectric polarization of KSrBi2Ta3O12 thin films

KSrBi2Ta3O12 (KSBT, in which there should be three TaO6 octahedra between neighboring (Bi2O2)2+ layers), was designed to improve ferroelectric polarization of SrBi2Ta2O9 (SBT). Thin films of SBT and KSBT were fabricated on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition for comparison study. No x-ray diffraction peaks of KTaO3 could be detected in the XRD patterns of the KSBT films, indicating a single phase of KSBT was obtained. The measured remnant polarization (2Pr) values of SBT and KSBT films were 3.6 μC/cm2 and 15.6 μC/cm2, respectively. The possible microstructural background responsible for the 4-times improved polarization was discussed. Furthermore, excellent ferroelectric fatigue-free property, retention property, and dielectric property of the KSBT films were exhibited experimentally. These results indicate that other than conventional site engineering such as substitution, adjusting the octahedra number between neighboring (Bi2O2)2+ layers is an alternative way to improve polarization of SBT while keeping its fatigue-free characteristics.