Effect of Excess Lead Addition on Processing of Sol-Gel Derived Lanthanum-Modified Lead Zirconate Titanate Thin Film

Abstract

Sol-gel-derived lanthanum-modified lead zirconate titanate (PLZT) thin films with a La/Zr/Ti ratio of 10/65/35 and a lead lanthanum titanate (PLT) thin seeding layer were successfully deposited on an indium tin oxide (ITO)-coated soda lime glass substrate at 500°C. Effects of excess lead addition of different concentrations in the precursor solution on the electrical properties of the resultant PLZT thin films were investigated. As a result, the relative permittivity increased and the dissipation factor decreased with the increase of excess lead concentration. Excess lead of 30 mol% was indispensable for obtaining PLZT thin film with good ferroelectricity. In addition, the resultant films showed more than 60% transmittance in the visible region.

Photochemical Solution Deposition of Lead-Based Ferroelectric Films: Avoiding the PbO-Excess Addition at Last

“…When the lead loss is compensated by incorporating a PbO excess, then the volume of the perovskite phase present in the films is known to increase . It is generally accepted that the PbO excess present in the amorphous film also leads to a decrease on the crystallization temperature of the ceramic material . Some authors have pointed that the lead excess present in the films can act as a flux for crystal growth or as a network modifier improving the mobility of the system, thus enhancing crystallization kinetics.…”

“…Improved electrical properties are obtained in these films when a certain amount of lead excess is present within their microstructure. Some authors , have proposed that the remaining PbO excess can improve the interfaces of the films by avoiding the formation of low dielectric space charge layers and oxygen vacancies in the material.…”

“…In spite of the drastic consequences associated with the use of low annealing temperatures and null amounts of lead excess, a remarkable ferroelectric response, with no internal bias fields, is obtained for the films of this work ( P r = 14 μC/cm 2 , E c = 175 kV/cm) which has not been reproducible before for any ferroelectric lead-based material processed under similar conditions. For example, an addition of 30 mol % of lead excess to the solution is observed to be necessary to crystallize PLZT films at temperatures near 500 °C . Conversely, annealing temperatures of 650 °C together with certain strategic approaches (PbO atmosphere powders and PbO overcoats) is required to obtain single-phase ferroelectric PZT films from stoichiometric solutions with no lead excess .…”

“…6 It is generally accepted that the PbO excess present in the amorphous film also leads to a decrease on the crystallization temperature of the ceramic material. 7 Some authors have pointed that the lead excess present in the films can act as a flux for crystal growth 8 or as a network modifier improving the mobility of the system, 9 thus enhancing crystallization kinetics. Anyway, additions of PbO excess to lead-based ferro-piezoelectric compositions (in both bulk ceramic and thin film conformations) remain representing the state-of-the-art in the preparation of these multifunctional materials.…”

Optimization of Pb Content in a Precursor Solution for the Fabrication of (Pb,La)(Zr,Ti)O3Films for Optical Applications by Chemical Solution Deposition

“…We have reported the La content dependence of electrooptic properties of PLZT films fabricated by CSD [7]. In case of the fabrication of Pb-system films by CSD, precursor solutions generally involve excess Pb due to the compensation of vaporized Pb components during [8,9]. This paper describes the optimization of the Pb content in precursor solutions used for fabricating optical PLZT films with fine microstructures.…”