Temperature-dependent far-infrared reflectance of an epitaxial (BaTiO3)8/(SrTiO3)4 superlattice

Abstract

Infrared reflectance spectra of the polar optic phonons in a [(BaTiO3)8/(SrTiO3)4]50 superlattice over the temperature range 8 to 650 K are reported. The spectra exhibit lattice vibration features typical of the perovskite constituents, BaTiO3 and SrTiO3. Using the effective medium approximation for multilayers systems and a fitting procedure, we were able to successfully simulate the infrared reflectivity of the superlattice structures and extract the parameters and dielectric functions of the phonons. When applied at varying temperatures, this approach provides the parameters of the zone-center polar phonons and their temperature dependence. Comparing these results with x-ray diffraction we identified some anomalies in phonon behavior related to the phase transitions that the superlattice undergoes.

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…”

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

“…As discussed above, the experimental information regarding symmetry of the STO m /BTO M−m superlattice varies considerably, mainly suggesting different STO phases, starting from tetragonal to orthorhombic (and monoclinic in the first principles calculations [29][30][31]. We limit our superlattice model to the tetragonal symmetry as suggested in recent experiment studies [12][13][14] and develop a model on the basis of the space-group symmetry relations.…”

“…It was also demonstrated that the tetragonal phase for STO 10 /BTO 10 superlattice remains stable down to 77 K, while the phase transition to the paraelectric state is diffused and shifted up to T c = 650 − 700 K 25 . Lastly, the very recent study 14 claims that strained [STO 4 /BTO 8 ] 50 superlattice on the DyScO 3 (110) has the tetragonal P4mm symmetry below 550 K (another phase transition between 200 and 300 K was also suggested 14 ).…”

“…Numerous experimental studies were performed recently on STO/BTO superlattices [10][11][12][13][14][15] .…”

“…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 .…”