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Keywords:

  • ferroelectrics;
  • PbTiO3;
  • nanodot arrays;
  • self assembly;
  • piezoresponse force microscopy

Abstract

A facile route is presented for the fabrication of spherical PbTiO3 (PTO) nanodot arrays on platinized silicon substrates using PbO vapor phase reaction sputtering on micellar monolayer films of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) loaded with TiO2 sol–gel precursor. Short exposure to PbO transforms the amorphous TiO2 into polycrystalline PTO, while keeping the inherent size and periodicity of TiO2 nanodots. HRTEM images show that the spherical PTO nanodots, with an average size and height of 63 nm and 40 nm, respectively, are fixed on the Pt supported by residual carbon. XPS narrow scan spectra of Ti 2p and O 1s strongly verify the evolution of chemical identity and the reduction of the Ti-O binding energy from TiO2 to PTO. The amplitude and phase images of piezoelectric force microscopy (PFM) confirm a multidomain structure attributed by the crystalline orientation of the PTO nanodots. Furthermore, the discrete PTO nanodots show remarkable switching properties due to the low strain field induced by the small lateral size, and the absence of domain pinning effects by grain boundary.