Papers Abstract

Interface Controlled Growth of Single-Crystalline PbTiO3 Nanostructured Arrays
PbTiO3 (PTO) ferroelectric perovskite has appealing electromechanical characteristics such as low aging rate of the dielectric constant, a high pyroelectric coefficient, a high piezoelectric voltage constant (gij), and a high Curie temperature of 490 °C. However, the high tetragonality of PTO ceramics makes them difficult to be synthesized via conventional high-temperature techniques. Here, a novel synthesis methodology is reported that results in epitaxial growth of a vertically aligned array of PTO nanofibers on a Ti metal substrate. High quality single crystal PTO nanofibers oriented along the [001] PTO direction were obtained on a (110) oriented TiO2 seed layer using a low-temperature hydrothermal synthesis technique. Fundamental understanding of the nucleation and growth criterion is provided through a combination of modeling of the geometric matching of crystal surfaces and experiments detailing the role of underlying TiO2 phase and interplanar atomic configuration. Crystal matching revealed good correspondence at an interface between parallel PTO (001) and rutile TiO2 (110) planes, in which six rows of Ti atoms in (010)PTO-type planes match with approximately seven rows of Ti atoms in (11̅0)rutile-type planes. In the orthogonal direction within the interface, four rows of Ti atoms in (1̅00)PTO-type planes correspond to five Ti atoms in (001̅)rutile-type planes. The lattice-matched interface appears to facilitate nucleation of epitaxial nanofiber growth. Availability of single crystalline PTO dense nanofiber arrays can give rise to a new generation of sensing and high-temperature energy harvesting applications.