Síntese e propriedades estruturais de filmes finos de PbTiO3 obtidos pelo método dos precursores poliméricos.

Abstract

Ferroelectric materials, discovered in 1921 by Joseph Valasek, exhibit spontaneous and reversible polarization upon application of an external electric field. They have been studied extensively since the 1940s, and have many applications, such as pyroelectric sensors, memory devices, electro-optical devices, capacitors, and others. Between them, lead titanate (PbTiO3 - PT) material stands out, which has a perovskite structure with tetragonal symmetry (P4mm space group), a Curie temperature of around ~490 °C (the ferroelectric-paraelectric phases transition temperature), low dielectric permittivity and high spontaneous polarization. These characteristics make the PbTiO3 a promising material for several applications, including infrared detectors and piezoelectric devices. With the advance of the synthesis and characterization techniques, however, new properties have been discovered and studied over the last years, whose real origin still remains unclear up today. In this way, this work aims the synthesis of PT thin films, as well as the study of the structural and microstructural properties. The films were synthesized by the Pechini’s method (or the polymeric precursors method), and their structural and microstructural characterizations were performed by X-ray diffraction (XRD), Raman spectroscopy (RS) and atomic force microscopy (AFM) techniques.