Enhancement of PbZrO3 polarization using a Ti seed layer for energy storage application

Abstract

Enhancement of lead zirconate (PbZrO3) polarization is achieved by using a titanium seed layer on alumina polycrystalline substrate. Thanks to the reduction of the lattice mismatch between the platinum electrode (3.92 Å) and the PbZrO3 films (4.14 Å), lead zirconate thin films oriented along the (111) direction with an orientation factor of around 65 % has been obtained. The (111) PbZrO3 presents an increase of 56% of the polarization compared to the (100) PbZrO3. This enhancement is responsible of the higher recoverable energy storage density obtained in the (111) PbZrO3 thin films (8 J/cm 3 at 600 kV/cm with an efficiency of 72%). The (111) PbZrO3 also has a higher figure of merit, which indicates that the (111) crystallographic plan is the most favorable direction for energy storage.

Crystallographic orientation dependence of ferroelectric domain walls in antiferroelectric lead zirconate thin films

“…The samples are prepared by a sol-gel process detailed elsewhere [3]. The precursor solution has been deposited at 4000 rpm during 25 s by a multi-step spin coating process on a polished alumina substrate.…”

“…The overall PbZrO3 films thickness is 800 nm. To modify the crystallographic orientation of the thin layers, a 2nm Ti seed layer has been deposited on the platinum layer of one sample before the deposition of the solution [3]. This permits us to reduce the lattice mismatch between the Pt electrode and the PbZrO3 films [3].…”

“…To modify the crystallographic orientation of the thin layers, a 2nm Ti seed layer has been deposited on the platinum layer of one sample before the deposition of the solution [3]. This permits us to reduce the lattice mismatch between the Pt electrode and the PbZrO3 films [3]. The structure and phase purity of the films were analyzed using a Bruker D8X-ray diffractometer (XRD) with CuKα radiation.…”

“…Thanks to the use of a Ti seed layer, the PbZrO3 films are oriented along the (111) direction at 70 %. During the annealing process, the Ti seed layer forms an intermetallic (Pt3Ti) layer with the platinum bottom electrode [10][11], reducing the lattice mismatch between the (111) oriented platinum bottom electrode and the PbZrO3 thin films [3]. Thus, we have two samples with two crystallographic configurations: one highly oriented in the (100) direction and the other with a preferential orientation in the (111) direction but with other orientations.…”

“…Ferroelectric materials are increasingly being considered as critical components in next generation nonvolatile memories [1], actuators and energy storage devices [2], [3]. For the last applications, it is necessary to have a great polarization and a low switching field between the antiferroelectric and ferroelectric phase.…”