Abstract
We describe the characterization, ferroelectric phase stability and polarization switching in strain-free macroscopic assemblies of 50-100 nm wide PbZr0.3Ti0.7O3 (PZT) nanostructures (ferroelectric nanosponges). The structures present uniquely large areas and volumes of PZT where the microstructure is spatially modulated and the composition is homogeneous. Variable temperature powder X-ray diffraction (XRD) studies show that the global structure is tetragonal at room temperature and undergoes a reversible tetragonal to cubic phase transition on heating/cooling. Our studies indicate that this transition temperature is 30-50°C lower than unstructured PZT of the same composition. To characterize and confirm that the structures are ferroelectric we have utilized piezoresponse force spectroscopy and we demonstrate that the switching polarization can be spatially mapped within the structures. Corresponding polarization distributions have been calculated for the bulk and nanostructured materials using a two-parameter direct variational method based on Landau-Ginzburg-Devonshire equation. Our studies correlate global and local characterization of ferroelectric nanostructures revealing that in the nanosponges tetragonal and ferroelectric PZT is stabilized and open a pathway for effective studies of nanoscale ferroelectrics in large volumes.
