Microstructure and piezoelectric properties of sub-80 nm high polycrystalline SrBi2Ta2O9 nanostructures within well-ordered arrays

Well-ordered arrays of sub-80 nm high SrBi2Ta2O9 nanostructures were fabricated on SrTiO3:Nb (111) single-crystal substrates by latex sphere lithography. The as-prepared nanostructures have a pyramid-like shape with around 220 nm lateral dimension at half their height. After annealing, the pyramid-like shape changes due to the formation of nano-sized SrBi2Ta2O9 grains of high crystal anisotropy in the individual nanostructures. Microstructure and piezoelectric properties of the nanostructures were investigated by cross-sectional transmission electron microscopy and piezoresponse force microscopy,, respectively. Scattering in piezoelectric strain constants d(33) was observed, probably arising from varying orientations, high anisotropy, and interfacial diffusion layer of the polycrystalline SrBi2Ta2O9 nanostructures on SrTiO3. The d(33) increases continuously with dc bias and reaches 8 pm/V at a bias of 20 V. The size effect on piezoelectric properties of SrBi2Ta2O9 was found to be much less severe than that in BaTiO3. The acquired piezoresponse hysteresis loops proved that 30 nm high SrBi2Ta2O9 nanostructures are still ferroelectric. (C) 2004 American Institute of Physics.