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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. [ABSTRACT FROM AUTHOR]

Brillouin scattering was measured on a ferroelectric 0.44Pb(Mg1/3Nb2/3)O3-0.56PbTiO3(PMN-56PT) single crystal with weak quenched random fields in the polarized (VV) and depolarized (VH) scattering geometries over a wide temperature range. The VH- and VV- central peaks (CPs) related to the transverse and longitudinal polarization fluctuations of polar nanoregions (PNRs) were successfully observed in a paraelectric cubic phase. The inverse relaxation time (1/τCP) determined by the VH-CP indicates the stretched slowing down above the Curie temperature (∼ 533 K). The temperature dependence of the average size of dynamic PNRs was estimated. [ABSTRACT FROM PUBLISHER]

Elastic properties of relaxor ferroelectric 0.44Pb(Mg1/3Nb2/3)O3-0.56PbTiO3single crystals have been studied under zero and external electric field along [100]-direction by micro-Brillouin scattering. Here we show the ability to move the ferroelectric multidomains toward a single domain state by the application of electric field. In the vicinity of TC-T= 260°C, the anomalous change of C11in a paraelectric cubic phase was well reproduced by the power law which exhibits the three dimensional polarization fluctuations. The order-disorder nature of the ferroelectric phase transition was confirmed by the analysis of sound attenuation based on the theoretical model by Levanyuk et al. [ABSTRACT FROM AUTHOR]

The broadband gigahertz dynamics of a ferroelectric phase transition of the 2.5%Li-doped KTa 1- x Nb x O 3 crystals with x = 0.38 (KLTN/2.5/38) was investigated by inelastic light scattering. Its phase transition was found to be slightly diffused type due to weak random fields (RFs) caused by disorder in B-site of perovskite structure. The microscopic origin of the central peak (CP) and the local symmetry of the polar nanoregions (PNRs) in the cubic phase were studied by Raman scattering. In Brillouin scattering, the remarkable elastic anomaly of the longitudinal acoustic (LA) mode was observed near paraelectric cubic to ferroelectric tetragonal phase transition temperature, T C-T = 46 °C, which is attributed to the coupling between fluctuating local polarization in PNRs and the LA mode. The intermediate temperature, T * ∼ 97 °C, at which a dynamic to static transition of PNRs occurs, was determined from the significant increase of damping and intensity of the LA mode and the CP upon cooling. In the vicinity of the T C-T , a slightly stretched slowing down of the relaxation time, τ CP , a feature of order-disorder nature of the ferroelectric phase transition with weak RFs, was clearly observed. [ABSTRACT FROM AUTHOR]