Anomaly in the Infrared Active Phonon Modes and Its Relationship to the Dielectric Constant of (Ba_1-xSr_x)(Mg _1/3Ta _2/3)O ₃ Compound

Abstract

A characteristic change in the dielectric properties with A-site substitution is known in complex perovskite compounds, (Ba, Sr)(B', B")O3, which are expected to be applied to dielectric resonators. Recently, a phase transformation upon tilting of oxygen octahedra has been found in some of the compounds. However the oxygen tilting transformation has not been considered to affect the dielectric constant explicitly. To clarify the relationship between the dielectric constant and the phase transformation, dielectric properties of a solid-solution system, (Ba1-x Sr x )(Mg1/3Ta2/3)O3, have been studied. The origin of the dielectric constant, the polar mode of the lattice vibration, has been investigated using infrared reflectivity spectroscopy and the Kramers-Kronig analysis. It was found that the phase transformation due to the tilting of the oxygen octahedra clearly affects polar phonon modes of the compound. The origin of the change in the dielectric properties with Sr concentration is discussed referring to the behavior of polar phonon modes.

Far infrared reflection study on structure–property relationship of Ba[Mg(1−x)/3ZrxTa2(1−x)/3]O3 ceramics

“…concentration. The distortion of the oxygen octahedron [29] may contribute to this transformation. The polar modes that disappeared in the FIR reflection spectra may be attributed to the ordered phase with the antiphase tilting of the oxygen octahedron.…”

“…The polar modes that disappeared in the FIR reflection spectra may be attributed to the ordered phase with the antiphase tilting of the oxygen octahedron. [29] The distortion of oxygen octahedron leads directly to phase transformation [29,30] of these ceramics. Therefore, the phase transformation resulted in the modification of the polar modes of the lattice vibration.…”

Structure and optical properties of Sn4+ doped Ba(Mg1/3Nb2/3)O3 transparent ceramics

“…However, in the spectroscopy results of S48, the band at 264 cm À 1 of E g (Nb) disappears, indicating that S48 does not exhibit ordered symmetry. In addition, the red-shift of E g (O), the blue-shift of A 1g (Nb) and their broad line widths imply the effect of the cell distortion with tilting of the oxygen octahedra [25], which is due to the influence of the replacement of the B-site ions by Sn 4 þ doping. Replacement by Sn 4 þ also has an appreciable influence on the A-O and B-O bond characters, leading to the split of the band caused by the lattice vibrations of Ba 2 þ (as shown in Fig.…”

Correlation of Microwave Dielectric Properties and Normal Vibration Modes of Ba(Mg1/3Ta2/3)O3-Series Materials

“…Since the dielectric properties at microwave frequencies are mainly contributed from the ionic polarization, the study of phonon vibration spectra of Ba(B 1/3 B 2/3 )O 3 has been of particular interest [5][6][7][8][9][10][11][12]. Recently, the Raman phonons [13] and the normal mode for resonant peaks in FTIR spectra [14] in Ba(Mg 1/3 Ta 2/3 )O 3 -Ba(Mg 1/3 Nb 2/3 )O 3 , BMT-BMN, materials were unambiguously identified.…”