Observing the superparaelectric limit of relaxor (Na_(1/2)Bi_(1/2))_(0.9)Ba_(0.1)TiO_3 nanocrystals

摘要

Applications of ferroelectric materials for nonvolatile memory, data storage devices, nanosensors, and nanoactuators necessitate fundamental studies of ferroelectric behavior, including the presence of switchable polarization and switching behavior, on the nanoscale. Here the authors investigated the switching properties of (Na_(1/2)Bi_(1/2))_(0.9)Ba_(0.1)TiO_3 nanocrystals prepared by a mist deposition technique using piezoresponse force microscopy (PFM) and spectroscopy. By using stiff cantilevers, reliable PFM data have been obtained and local electromechanical response was measured. The transition from ferroelectric to superparaelectric behavior in these nanocrystals was observed at sizes of ～10 nm. The effects of particle shape on the PFM imaging are also discussed.