Interface Controlled Growth of Single-Crystalline PbTiO₃ Nanostructured Arrays

다국어 초록 (Multilingual Abstract)

<P>PbTiO<SUB>3</SUB> (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 (<I>g</I><SUB><I>ij</I></SUB>), 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 TiO<SUB>2</SUB> 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 TiO<SUB>2</SUB> phase and interplanar atomic configuration. Crystal matching revealed good correspondence at an interface between parallel PTO (001) and rutile TiO<SUB>2</SUB> (110) planes, in which six rows of Ti atoms in (010)<SUB>PTO</SUB>-type planes match with approximately seven rows of Ti atoms in (11̅0)<SUB>rutile</SUB>-type planes. In the orthogonal direction within the interface, four rows of Ti atoms in (1̅00)<SUB>PTO</SUB>-type planes correspond to five Ti atoms in (001̅)<SUB>rutile</SUB>-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.</P>
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