Brillouin Scattering and First-Principles Studies of BaMO3 (M = Ti, Zr, and Cu) Perovskites

Abstract

Perovskite oxides with the general formula ABO₃ comprise a large number of families among the structures of oxide-based materials, and currently, several perovskite structures have been identified. From a variety of compositions and structures, various functions are observed in perovskite compounds, and therefore, they became very useful for various applications in the electronic and medical industries. One of the most puzzling issues for perovskite compounds is the understanding of the vibration and relaxation dynamics in the gigahertz range. In that sense, the micro-Brillouin scattering system is a very effective tool to probe the gigahertz dynamics, and also, first-principles calculations can be used to describe the phonon structure with different atomic contributions. The micro-Brillouin scattering system and first-principles calculations provide the fundamental information on a variety of vibration and relaxation processes related to structural phase transitions under different external conditions such as temperature, electric field, and pressure. This review article summarizes the Brillouin scattering and first-principles studies on BaMO₃ (M = Ti, Zr, and Cu). Through a detailed analysis of the existing results, we summarize the existing limitations and future perspectives in these research areas, which may propel the development of different perovskite ferroelectrics and extend their practical application areas.

Keywords: Brillouin scattering; barium oxide; ferroelectric; first-principles calculation; perovskite.

Figure 1

The 2D and 3D view of ABO₃-type cubic perovskites.

Figure 2

A schematic illustration of micro-Brillouin scattering setup.

Figure 3

Brillouin scattering spectra at 398 and 403 K of (100)-oriented BaTiO₃ single crystals.

Figure 4

The temperature dependences of (a) frequency shift (υ_LA) and (b) FWHM (ΓLA) of LA phonon mode of 100-BT single crystals measured in ZFC (blue solid symbols) and FC (red solid half-filled symbols) processes [24].

Figure 5

(a) A set of typical Brillouin scattering spectra BTO single crystals in the ferroelectric tetragonal phase at some selected electric fields at 303 K; (b) shows the orientation of a and c domains.

Figure 6

(a) A set of typical Brillouin scattering spectra at some selected temperatures and (b) a contour color map of intensity versus temperature and frequency of BZO single crystals [13].

Figure 7

(a) Time-domain waveform and (b) the power spectra of a BaZrO₃ single crystal converted from time-domain waveforms at 8 K.

Figure 8

Phonon dispersion relation of BZO crystals [13].

Figure 9

Partial and total phonon density of states of BZO crystals. Inset shows the contribution of Zr atom.

Figure 10

Calculated IR active TO mode frequencies of BZO crystals in the cubic phase.

Figure 11

Phonon spectra of BaCuO₃ at zero pressure.

Figure 12

Density of phonon states of BaCuO₃ at zero pressure.

Figure 13

Comparison of different elastic moduli of BaCuO₃ with other perovskites.

Figure 14

The energy dependence of the (a) real and (b) imaginary part of the dielectric constant of BaCuO₃ at some selected pressures. Different offset values are set to visualize the optical spectra clearly.

Figure 15

Partial DOS of Cu-3d and O-2p orbitals at 16, 18, 20, and 24 GPa.

Figure 16

The energy dependence of (a) absorption coefficient and (b) conductivity of BaCuO₃ at some selected pressures. Different offset values are set to visualize the optical spectra.