Epitaxial growth and the crystallographic, dielectric, and pyroelectric properties of lanthanum-modified lead titanate thin films

Abstract

Using an rf-magnetron sputtering method, highly c-axis-oriented La-modified PbTiO3 (PLT) thin films with compositions of Pb1−xLaxTi1−x/4O3, where x=0.05, 0.10, and 0.15, have been obtained on MgO single-crystal and epitaxial Pt thin-film substrates under conditions of low gas pressure and low deposition rate. The degree of c-axis orientation of the PLT films decreases, and the tetragonality of PLT becomes smaller with increasing La content. The Curie point of the films decreases at a rate of 18 °C/at. % of La with an increase of La content. D-E hysteresis loops were observed, and these became slim and symmetric with increasing La. It was found that significant pyroelectric currents are detected on all as-grown specimens even without a poling treatment, and the directions are the same in all specimens. Relative dielectric constant εr decreases, and pyroelectric coefficient γ increases with increasing degree of c-axis orientation. εr and γ became large with increase of La content in the films. Considering the figure of merit for pyroelectric infrared detection and the temperature coefficient of γ, it was concluded that PLT films with x=0.10 were good material for pyroelectric infrared detectors.

Impact of misfit relaxation and a-domain formation on the electrical properties of tetragonal PbZr0.4Ti0.6O3/PbZr0.2Ti0.8O3 thin film heterostructures: Experiment and theoretical approach

“…This term increases the energy due to polarization difference at the interface. For the structures shown in Fig.1a-d The single c-domain state of the bottom layer induces a c-component of the polarization in a-domains of the top layer and couples to the c-domain as in (8). Therefore the electrostatic coupling can be described as…”

“…[7] Depending on the used substrate-film combination, either compressive or tensile strains can be introduced, the latter being able to tilt the polarization vector from the out-of-plane into the in-plane direction. [8] Furthermore the polarization can be increased via strain-polarization coupling, [9] even though this is not always as extensive as expected from the increased tetragonality. [10][11][12][13] In this way ferroelectric films can be tuned to exhibit either polarization values superior to the corresponding bulk material or an outstanding dielectric constant.…”

Sol-gel processing and physic-chemical characterization of La and Ce doped lead titanate ceramics

“…The structure transforms from tetragonal to pseudo cubic. Occurrence of the cubic phase has been reported for concentrations higher than 25% [5,6]. Raman spectroscopy constitutes a very useful tool for identification of phases.…”

Electric field-induced magnetization switching in interface-coupled multiferroic heterostructures: a highly-dense, non-volatile, and ultra-low-energy computing paradigm

“…Modeling the P -layer as a parallel plate capacitor and using a relative dielectric constant of 1000 [41], the capacitance C of the layer becomes ∼0.4 fF. If the P -layer is accessed with a 10 µm long silver wire with resistivity ∼2.6 µΩ-cm [42], the resistance R becomes ∼3 kΩ.…”