Resonance Raman scattering of perovskite-type relaxor ferroelectrics under nonambient conditions

Flor, G. de la; Wehber, M.; Rohrbeck, A.; Aroyo, M. I.; Bismayer, U.; Mihailova, Boriana

doi:10.1103/physrevb.90.064107

Cited by 7 publications

(15 citation statements)

References 43 publications

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“…However, a smaller number of resolved peaks are experimentally observed at all temperatures, because of peak overlapping and/or very weak intensities. Hence, for each compound, we first fitted the spectrum measured at the lowest temperature, and the number of included peaks was chosen so that dI / I < 1 for all peaks, where I and dI are the calculated integrated intensity and the corresponding uncertainty . Then, the same number of peaks was used as a starting model for the spectrum measured at the next higher temperature, and if for a certain peak dI / I ≥ 1, that peak was removed.…”

Section: Resultsmentioning

confidence: 99%

Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study

Prasetyo

Mihailova

Nugroho

et al. 2016

J. Raman Spectrosc.

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The temperature evolution of the Raman scattering of Pb1 − xBi4 + xTi4 − xMnxO15 (x = 0.2 and 0.4) on cooling from 850 to 140–130 K was studied in order to elucidate the effect of B‐site Mn3+ doping accompanied by the increase in the A‐site Bi3+ content on the structural transformations in four‐layer Aurivillius‐type compound (An − 1Bi2BnO3n + 3, n = 4). The ferroelectric–paraelectric transition (Tc ~800 K for x = 0.2 and ~765 K for x = 0.4) is well mirrored by the Raman scattering near 60 cm−1 arising from the so‐called rigid layer mode. The temperature dependence of the phonon mode near 42 cm−1 arising from A‐site Pb/Bi displacements indicates a second structural transformation near 570 K and 400 K for x = 0.2 and 0.4, respectively, similar to that observed for Mn‐free PbBi4Ti4O15. This structural alteration resembles a thermodynamically second‐order phase transition for all three compounds and the critical temperature (Ta) decreases with the increase in the A‐site Bi3+ amount, related to the heterovalent substitution (Mn3+ for Ti4+) on the B site; Ta = 600, 570, 400 K for x = 0, 0.2, 0.4, respectively. The BO6 tilting and bending mode near 220 cm−1 also shows an anomaly at Ta, and, thus, this second structural transformation was attributed to subtle rearrangements of A‐site cations accompanied by octahedral BO6 tilting in the perovskite‐like blocks. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study

Prasetyo

Mihailova

Nugroho

et al. 2016

J. Raman Spectrosc.

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“…The RRS selection rules are derived from the inspection of the direct product of the representations characterizing the transformation properties of the electron transition and the phonon [26]. In ABO 3 -type materials with transition-metal cations at the B site the top of the valence band is dominated by O(2p) electron states (t 1u symmetry in the cubic phase), while the bottom of the conduction band is dominated by B-cation(d) electron states with t 2g or e g symmetry in the cubic phase [26]. Hence, the analysis of the possible direct products for cubic relaxors reveals that the phonon modes…”

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confidence: 99%

“…+ + , which are Raman-active under non-resonance conditions, are symmetry-forbidden to appear in RRS when the excitation photon energy is close to the energy gap, because the direct products of the corresponding cubic phonon and electron-transition representations have odd parities [26]. Instead, the T 1u and T 2u phonon modes are symmetry-allowed to couple with the O(2p) ⟶ B-cation(d) electron transitions and generate RRS.…”

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confidence: 99%

“…Resonance Raman spectroscopy has recently been proved to be very sensitive to coupled local polar distortions in perovskites [26]. Solid-state resonance Raman scattering (RRS) is a three-particle interaction process between the exciting photon, the excited electron and a phonon that is symmetryallowed to couple with the electron, when the energy of the incident photon is in the vicinity of the energy gap E gap .…”

Section: Introductionmentioning

confidence: 99%

“…Hence, in the case of dielectrics, LO phonons that carry polarity generate strong RRS, facilitating the detection of subtle polar distortions under resonance conditions. In a previous study we have applied resonance Raman spectroscopy complemented by group-theory analysis to stoichiometric PbSc 0.5 Ta 0.5 O 3 and PbSc 0.5 Nb 0.5 O 3 , using a laser wavelength λ = 325 nm (3.8 eV) [26]. The excitation photon energy was chosen to be slightly above the energy gap E 3.2 eV gap ∼ but in the vicinity of the broad maximum of the optical dielectric permittivity [28].…”

Section: Introductionmentioning

confidence: 99%

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The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy

Rohrbeck

Flor

Aroyo

et al. 2016

J. Phys.: Condens. Matter

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Resonance Raman spectroscopy was applied to doped PbSc0.5Ta0.5O3 and PbSc0.5Nb0.5O3 relaxor ferroelectrics, to better understand the effect of composition disorder on the mesoscopic-scale polar order in complex perovskite-type (ABO3) ferroelectrics. The excitation photon energy used was 3.8 eV, which is slightly above the energy gap and corresponds to the maximum of the optical dielectric permittivity. Group-theory analysis reveals that the resonance Raman scattering (RRS) observed under these conditions is allowed only in polar crystal classes. Therefore, RRS is dominated by the atomic dynamics of nanoregions with coherent polar distortions, which considerably facilitates the comparison of polar order in various compounds. The results show that A-site doping (Ba(2+), Sr(2+), La(3+), Bi(3+)) has significantly stronger effect on the structural polarity than the introduction of a third element at the B site (Nb(5+) or Sn(4+) doped in PbSc0.5Ta0.5O3). The A-site substitution by cations that in contrast to Pb(2+) have isotropic outermost electron shells disturbs the system of lone-pair electrons, thus reducing the correlation length of coupled polar distortions and the strength of the electric field associated with the mean polarization of polar nanoregions. A-site doping with larger cations (Ba(2+)) augments the polar deformation of the individual BO6 octahedra due to local elastic fields. As a result, such A-site doping intensifies the initial structural polarity at high temperatures and prevails the enlargement of the polar fraction at low temperatures. A-site doping with smaller cations (Sr(2+), La(3+)), regardless if they are isovalent or aliovalent to Pb(2+), increases the correlation length of antiferrodistortive order (BO6 tilts), which in turn assists the development of double-perovskite structure with coherent local polar distortions. A-site doping with aliovalent cations (Bi(3+)) having the same outermost electron shell and ionic radius as the host A-site Pb(2+) cations leads to stronger coupling along the -B-O-B- bond linkages due to enhanced random local electric fields.

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Thermally-activated electron hopping in Fe-rich amphiboles: Implications for the high-conductivity anomalies in subduction zones

et al. 2023

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Resonance Raman scattering of perovskite-type relaxor ferroelectrics under nonambient conditions

Cited by 7 publications

References 43 publications

Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study

Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study

The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy

Thermally-activated electron hopping in Fe-rich amphiboles: Implications for the high-conductivity anomalies in subduction zones

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Resonance Raman scattering of perovskite-type relaxor ferroelectrics under nonambient conditions

Cited by 7 publications

References 43 publications

Structural transformations in Pb1 − xBi4 + xTi4 − xMnxO15(x = 0.2 and 0.4): a Raman scattering study

Structural transformations in Pb1 − xBi4 + xTi4 − xMnxO15(x = 0.2 and 0.4): a Raman scattering study

The effect of chemical variations on the structural polarity of relaxor ferroelectrics studied by resonance Raman spectroscopy

Thermally-activated electron hopping in Fe-rich amphiboles: Implications for the high-conductivity anomalies in subduction zones

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Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study

Structural transformations in Pb_1 − xBi_4 + xTi_4 − xMn_xO₁₅(x = 0.2 and 0.4): a Raman scattering study