Giant Enhancement of Polarization and Strong Improvement of Retention in Epitaxial Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$-Based Nanocomposites

Abstract

In Ba$_{0.6}$Sr$_{0.4}$TiO$_{3}$ (BSTO)-based epitaxial nanocomposite films increased P r values are demonstrated by up to a factor of 3 compared to standard BSTO films. A strongly reduced temperature coefficient of polarization retention is also obtained, i.e., 0.07% °C$^{−1}$ compared to 0.24% °C$^{−1}$ . Piezopoling with only marginal leakage current is also achieved up to 200 °C, the highest temperature studied. The origin of the improved performance is the incorporation of Sm$_{2}$O$_{3}$ nanopillars in the films which acted as stiff vertical nanoscaffolds, inducing a strong tetragonal distortion in the BSTO (up to 1.033(7) in terms of the out-of-plane/in-plane lattice dimensions). The films have comparable performance to industry-standard Pb(Zr,Ti)O$_{3}$ films, at the same time as being Pb-free.