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

Link:
Autor/in:
Erscheinungsjahr:
2017
Medientyp:
Text
Schlagworte:
  • Aurivillius structure-type
  • ferroelectric phase transition
  • phonon modes
  • temperature dependence
Beschreibung:
  • 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.
Lizenz:
  • info:eu-repo/semantics/closedAccess
Quellsystem:
Forschungsinformationssystem der UHH
Interne Metadaten
Quelldatensatz
oai:www.edit.fis.uni-hamburg.de:publications/3a2c71e2-2ab7-424b-b2af-695cc6feb19c