resumo
Nanoporous and dense ferroelectric PbTiO3 thin films are prepared by a modified sol-gel process. The presence of nanoporosity, with similar to 50 nm pore size formed using a block polymer as a structure-directing agent, markedly affects the microstructure, crystallization and ferroelectric properties of the film. The crystallization of the tetragonal phase is enhanced in nanoporous films. It is suggested that the decomposition of the block-copolymer in porous films triggers the crystallization of the perovskite phase at low temperatures via the local increase of temperature. Consequently, nanoporous films with improved tetragonality exhibit enhanced piezoelectric coefficients, switchable polarization and low local coercivity. By providing a means of achieving enhanced properties, nanoporosity may have a broad impact on the applications of ferroelectric thin films.
palavras-chave
RAMAN-SCATTERING; DESIGN; OXIDES
categoria
Materials Science; Physics
autores
Castro, A; Ferreira, P; Rodriguez, BJ; Vilarinho, PM
nossos autores
Alichandra Maria Gonçalves Castro
Estudante de doutoramento
Paula Celeste da Silva Ferreira
Investigador Coordenador
Paula Maria Lousada Silveirinha Vilarinho
Vice-Diretoragradecimentos
The authors are grateful to FCT, FEDER, and QREN-COMPETE for funding the project FCOMP-01-0124-FEDER-009356 (PTDC/CTM/098130/2008), the Associate Laboratory CICECO FCOMP-01-0124-FEDER-037271 (Pest-C/CTM/LA0011/2013) and the Doctoral fellowship SFRH/BD/67121/2009. P. Ferreira acknowledges the FCT for IF/00327/2013. Some of the measurements were performed on equipment funded by the Science Foundation Ireland (SFI07/IN1/B931). We acknowledge COST Action MP0904 SIMUFER for funding the Short Term Scientific Mission of A. Castro. We acknowledge Denise Denning from the Nanoscale Function group of Conway Institute of Biomolecular and Biomedical Research for assistance and discussion related to the Scanning Probe Microscopy measurements.