Self-assembly of 3-Dimensional Single Crystal Piezoelectric PbTiO3 Nanostructure Arrays

Over the past few decades, piezoelectric nanomaterials including nanotubes, nanorods and nanowires have been extensively studied because of their unique functional properties. Among piezoelectric materials nanomaterials,... [ view full abstract ]

Over the past few decades, piezoelectric nanomaterials including nanotubes, nanorods and nanowires have been extensively studied because of their unique functional properties. Among piezoelectric materials nanomaterials, PbTiO₃ has been quite appealing due to its low aging rate of dielectric constant, high voltage constant, and high Curie temperature of 490 ^oC. Also, PbTiO₃ has high tetragonality (c:a ratio of 1.063) which results in a smaller ratio of the planar-to-thickness coupling factor. However, the high tetragonality (high spontaneous strain) makes it is challenging to synthesize dense ceramic body of PbTiO₃ through a conventional high temperature synthesis. Here, we present synthesis of single crystal PbTiO₃ nanostructures using a low temperature hydrothermal synthesis process to avoid spontaneous fracturing. Depending on seeding and substrate orientation, different shapes of PbTiO₃ nanostructures such as nanowire, hierarchical and cross-hatch pattern 3-dimensional nanostructures were fabricated. Systematic characterizations were conducted on the PbTiO₃ nanostructures using X-ray diffraction (XRD), piezoresponse force microscope (PFM), and high resolution transmitted electron microscope microscopy (HRTEM). We further provide a fundamental understanding of the growth mechanism of PbTiO₃ nanostructures based on surface energies and crystallography.