A Comparative Analysis of BaTiO3/(Ba,Sr)TiO3 and BaTiO3/(Ba,Sr)TiO3/SrTiO3 Artificial Superlattices via Raman Spectroscopy

Abstract

superlattices are characterized via Raman spectroscopy. Special attention is paid to a comprehensive analysis of their polarized Raman spectra, especially, within a soft mode (E(1TO)) range. The shift of E(1TO) soft mode is found to be more pronounced for BaTiO 3 /Ba 50 Sr 50 TiO 3 /SrTiO 3 sample than for BaTiO 3 /Ba 50 Sr 50 TiO 3 , presumably owing to stronger 2D compression of BT layers and abruptly increased temperature of transition from ferroelectric to paraelectric phase.

A Comparative Analysis of Asymmetric (BaTiO3) (1 − x)Λ/(BaZrO3) xΛ Superlattices via X‐Ray Diffraction and Raman Spectroscopy

“…Moreover, according to the Raman spectroscopy, the strain in BT constituents seems to induce the monoclinic phase in them, decreasing to a large extent the disorder of Ti 4+ ions, which suggests the appearance of a polar phase in BZ layers, as follows from the drastically upshifted (by seven times) low-frequency E(1TO) soft mode and the unchanged A1(2TO) soft-mode component. erefore, in comparison with epitaxial structures with varying stoichiometry in one of the constituent layers [11][12][13], the design of superlattices with asymmetric constituent thickness at a constant modulation period allows one to achieve a much more drastic transformation of E(1TO) soft modes (by seven times in this study) over against the parent BT film. In this respect, the fabrication of superlattices with a predefined composition enables one to achieve the structures with tunable properties, which ensures their proper application.…”

“…Earlier, we have studied the PLD grown superlattices onto MgO substrates, where one constituent was BaTiO 3 and another was a solid solution with Ba atoms partly substituted with Sr, that is, Ba (1−x) Sr x TiO3 (BT/BST) [11][12][13]. In those systems, E(1TO) ferroelectric soft modes were monitored via Raman spectroscopy that is a powerful nondestructive tool for this purpose [2,4,9,14,15].…”

Origin of ferroelectricity in cubic phase of Hf substituted BaTiO3

“…Furthermore, in the Raman spectra of BaTi 1−x Hf x O 3 samples, modes around 260 and 520 cm −1 have a dominant A 1 (TO) character and are associated with the Ti-O vibrations [43,104,106]. With an increase in the Hf substitution, the Raman spectrum ranging from 180 cm −1 to 300 cm −1 transforms its nature with the disappearance and appearance of peaks in the said range.…”

“…Since the ionic radii of Hf 4+ (0.71 Å) is larger than Ti +4 (0.605 Å) [107], which may cause the elastic interaction between polar Ti 4+ rich regions and non-polar Hf 4+ regions, which may further results in the appearance of random strain fields in the samples that is also supported through the analysis of x-ray diffraction data using Williamson-Hall method. The 190 cm −1 A 1 (TO) mode is the result of strain-induced polar mode that generates due to the Hf doping [106]. The intensity of this new polar mode increases with Hf substitution.…”