Structural transformations in Pb sub(1-x)Bi sub(4+ x)Ti sub(4-x)Mn sub(x)O sub(15) (x=0.2 and 0.4): a Raman scattering study

The temperature evolution of the Raman scattering of Pb sub(1-x)Bi sub(4+ x)Ti sub(4-x)Mn sub(x)O sub(15) (x=0.2 and 0.4) on cooling from 850 to 140-130K was studied in order to elucidate the effect of B-site Mn super(3+) doping accompanied by the increase in the A-site Bi super(3+) content on the s...

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Bibliographic Details
Published in:Journal of Raman spectroscopy 2017-02, Vol.48 (2), p.292-297
Main Authors: Prasetyo, Anton, Mihailova, Boriana, Suendo, Veinardi, Nugroho, A A
Format: Article
Language:English
Subjects:
Alterations
Bending
Cooling effects
Evolution
Phonons
Raman scattering
Temperature dependence
Transformations
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Summary:The temperature evolution of the Raman scattering of Pb sub(1-x)Bi sub(4+ x)Ti sub(4-x)Mn sub(x)O sub(15) (x=0.2 and 0.4) on cooling from 850 to 140-130K was studied in order to elucidate the effect of B-site Mn super(3+) doping accompanied by the increase in the A-site Bi super(3+) content on the structural transformations in four-layer Aurivillius-type compound (A sub(n-1)Bi sub(2)B sub(n)O sub(3n+3), n=4). The ferroelectric-paraelectric transition (T sub(c) ~800K for x=0.2 and ~765K for x=0.4) is well mirrored by the Raman scattering near 60cm super(-1) arising from the so-called rigid layer mode. The temperature dependence of the phonon mode near 42cm super(-1) arising from A-site Pb/Bi displacements indicates a second structural transformation near 570K and 400K for x=0.2 and 0.4, respectively, similar to that observed for Mn-free PbBi sub(4)Ti sub(4)O sub(15). This structural alteration resembles a thermodynamically second-order phase transition for all three compounds and the critical temperature (T sub(a)) decreases with the increase in the A-site Bi super(3+) amount, related to the heterovalent substitution (Mn super(3+) for Ti super(4+)) on the B site; T sub(a)=600, 570, 400K for x=0, 0.2, 0.4, respectively. The BO sub(6) tilting and bending mode near 220cm super(-1) also shows an anomaly at T sub(a), and, thus, this second structural transformation was attributed to subtle rearrangements of A-site cations accompanied by octahedral BO sub(6) tilting in the perovskite-like blocks. The temperature evolution of phonon modes in four-layer Aurivillius-type PbBi sub(4)Ti sub(4)O sub(15) doped with Mn reveals structural transformations and chemistry-induced renormalization phenomena in this important class of magnetoelectric materials.
ISSN:0377-0486
1097-4555
DOI:10.1002/jrs.5030