Raman signatures of monoclinic distortion in (Ba_1−xSr_x)₃CaNb₂O₉ complex perovskites

Abstract

Octahedral tilting is most common distortion process observed in centrosymmetric perovskite compounds (ABO 3 ). Indeed, crucial physical properties of this oxide stem from the tilts of BO 6 rigid octahedra. In microwave ceramics with perovskite-type structure, there is a close relation between the temperature coefficient of resonant frequency and tilt system of the perovskite structure. However, in many cases, limited access facilities are needed to assign correctly the space group, including neutron scattering and transmission electron microscopy. Here, we combine the Raman scattering and group-theory calculations to probe the structural distortion in the perovskite (Ba 1-x Sr x ) 3 CaNb 2 O 9 solid solution, which exhibits a structural phase transition at x ≥ 0.7, from D 3d

Optical phonon modes in 1:2 ordered trigonal Ba3MgNb2O9 perovskite: Synergy of both classical and quantum methods

“…Recently, Ma et al designated the first one as symmetric stretching coming from localized 1:1 domains in coexistence with 1:2 regions 49,54 . This conclusion was supported by other previous works on partial disordered samples such as Ti‐doped Ca 3 B ′ B ″ 2 O 9 55 and (Ba 1‐ x Sr x ) 3 CaNb 2 O 9 16 . The Raman peak from 1:1 domains has less energy than the 1:2 peak from the trigonal lattice, which can be explained taking into account the different neighbors around Nb 5+ cations.…”

“…Within the scope of the atomic level, the microwave properties can be assessed from the vibrational spectroscopy. Raman spectroscopy is a recognized local sensitivity tool for probing the B ‐site ordering or phase transition induced by octahedral tilting in complex perovskites 15–17 . At the same time, the reflectance infrared spectroscopy may provide intrinsic dielectric properties carried out by the ionic polarization 18–21 .…”

“…Raman spectroscopy is a recognized local sensitivity tool for probing the B-site ordering or phase transition induced by octahedral tilting in complex perovskites. [15][16][17] At the same time, the reflectance infrared spectroscopy may provide intrinsic dielectric properties carried out by the ionic polarization. [18][19][20][21] This information is useful because it can estimate the atomic level origin of the dielectric tensor and dielectric loss from the polar phonon modes.…”

Calculation of the optical phonons in ordered Ba2MgWO6 perovskite using short‐range force field model

“…Raman and infrared spectroscopy became a useful tool to probe local disorder at B‐site and octahedral tilting in ordered perovskites by analyzing peak parameters such as intensity, position, width, and possible asymmetry . As a result of disorder, the A 1g mode starts to depict a broadening as a consequence of the antisite defects.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…They combined Raman scattering and group theory calculations to probe the structural distortion in the perovskite solid solution. Both phases are related by an octahedral tilting distortion . Shibano et al carried out a Raman spectroscopic determination of Sr/Ca ratios of calcite samples.…”