A novel preparation method, which involves the use of microemulsions, sol–gel chemistry and
chemical solution deposition, has been developed in this work for the preparation of layers of
PbTiO3 nanostructures
supported on SrTiO3
substrates. A transparent solution was first prepared by mixing a
PbTiO3
precursor sol and a microemulsion formed by water, cyclohexane and the surfactant
Brij 30 (polyoxyethylene(4) lauryl ether). The solution was deposited onto the
SrTiO3
substrate by spin-coating and dried under controlled conditions (temperature,
time and relative humidity) to favor the rearrangement of the micelles in
the deposited coat. After a rapid thermal treatment of crystallization at
650 °C, nanostructures
with uniform sizes of ∼40 nm diameter and showing periodicity in some zones of the substrate are obtained. The
analysis of these nanostructures by grazing-incidence x-ray synchrotron radiation indicates
that they have a perovskite structure with a preferred orientation and that they are under strained conditions. Thermal
treatments at higher temperatures produce the collapse of the ordered
nanoparticles’ network and the formation of larger isolated particles of
PbTiO3
with a truncated-pyramid morphology. Piezoresponse force microscopy
studies demonstrate that the spontaneous polarization of these
PbTiO3
nanostructures can be switched and that they have piezoelectric activity. These results
support the fabrication strategy here proposed as a promising approach for the preparation
of nanoferroelectrics onto substrates of possible interest in future nanoelectronic devices.