Infrared spectroscopy of an epitaxial BaTiO3/SrTiO3 superlattice grown on a (110) SmScO3 substrate

Abstract

Polarized infrared reflectance spectra of a BaTiO 3 /SrTiO 3 superlattice deposited on the (110) cut of SmScO 3 substrate and bare substrate have been studied in the broad temperature range from 10 to 650 K. Strong infrared anisotropy of the SmScO 3 substrate was observed and explained as a projection of B 1u and B 2u þ B 3u phonons into the (110) plane. In the polarization parallel to the c-axis below 200 cm À1 , an anomaly in the temperature dependence of the spectra was observed. Fitting the superlattice and substrate spectra, the parameters of optical phonons and their temperature dependence were determined. The superlattice phonon frequencies show only classical behavior, it means frequency hardening on cooling. Anisotropy was also found in the superlattice phonon frequencies and their contributions to static permittivity. V

Sr-induced dipole scatter in BaxSr1−xTiO3 : Insights from a transferable-bond valence-based interatomic potential

“…Looking forward, alloy BVMD potentials not only enable the prediction of macroscopic (lattice constants, polarization, structure phase transitions, and their temperatures) and microscopic (Ti displacements) physical properties of technologically important ferroelectric perovskite alloys such as BST, BZT, PZT, and PMN-PT but also the nanoscale design of new materials via compositional tuning and heterostructure/superlattice engineering. [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63] Supplemental Material…”

Far infrared and terahertz spectroscopy of ferroelectric soft modes in thin films: A review

“…The last type of films based on BTO and STO are BTO/STO superlattices. The effective SM behavior for the (BTO) 8 /(STO) 4 superlattices repeated 40 times (total thickness d = 192 nm) on DyScO 3 , SmScO 3 , TbScO 3 and EuScO 3 substrates was studied by Železný et al [82,83,84] using the polarized FTIR reflectance. In case of the film on SmScO 3 substrate also the temperature dependence was studied [83], but no FE PT was detected from the phonon behavior.…”

“…The effective SM behavior for the (BTO) 8 /(STO) 4 superlattices repeated 40 times (total thickness d = 192 nm) on DyScO 3 , SmScO 3 , TbScO 3 and EuScO 3 substrates was studied by Železný et al [82,83,84] using the polarized FTIR reflectance. In case of the film on SmScO 3 substrate also the temperature dependence was studied [83], but no FE PT was detected from the phonon behavior. The effective SM was split due to the substrate anisotropy and hardened gradually on cooling, up to rather high frequency ~150 cm -1 at 10 K. Also the Raman spectroscopy can be used as a sensitive tool for the FE order, because the polar phonons in crystals with centrosymmetric paraelectric phase become Raman active only in the FE phase.…”

Interface-induced enhancement of piezoelectricity in the (SrTiO3)m/(BaTiO3)M−m superlattice for energy harvesting applications

“…In these experiments it was initially proposed that at ambient temperatures BTO slabs have orthorhombic symmetry 19 , while later it was clarified 20 that BTO phase has a tetragonal symmetry with a polarization along the [001] direction. Orthorhombic STO slabs were found also in [STO 4 /BTO 8 ] 40 superlattice on the SmScO 3 (110) substrate with Curie temperature T c = 660 K 21 .…”

“…Thus, tetragonal phase of STO (cubic bulk STO lattice constant 3.905 Å) is stabilized, if STO slabs are in-plane tensilely strained, while BTO slabs (in-plane tetragonal bulk lattice constant 3.992 Å) are compressively strained, e.g., on the DyScO 3 (110) (with almost perfect square lattice with parameters 3.946 and 3.952 Å) 14 . Contrary, orthorhombic STO slab phase dominates, if STO slabs experience strong tensile in-plane strain, while BTO are almost unstrained, e.g., for superlattices on the SmScO 3 (110) (surface lattice constant 3.987 Å) 21 .…”