Ruiz-Fuertes, J., Gomis, O., Segura, A., Bettinelli, M., Burianek, M. and Muehlberg, M. (2018). Bandgap behavior and singularity of the domain-induced light scattering through the pressure-induced ferroelectric transition in relaxor ferroelectric A(x)Ba(1-x)Nb(2)O(6) (A: Sr,Ca). Appl. Phys. Lett., 112 (4). MELVILLE: AMER INST PHYSICS. ISSN 1077-3118

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Abstract

In this letter, we have investigated the electronic structure of A(x)Ba(1-x)Nb(2)O(6) relaxor ferroelectrics on the basis of optical absorption spectroscopy in unpoled single crystals with A = Sr and Ca under high pressure. The direct character of the fundamental transition could be established by fitting Urbach's rule to the photon energy dependence of the absorption edge yielding bandgaps of 3.44(1) eV and 3.57(1) eV for A = Sr and Ca, respectively. The light scattering by ferroelectric domains in the pre-edge spectral range has been studied as a function of composition and pressure. After confirming with x-ray diffraction the occurrence of the previously observed ferroelectric to paraelelectric phase transition at 4 GPa, the light scattering produced by micro-and nano-ferroelectric domains at 3.3 eV in Ca0.28Ba0.72Nb2O6 has been probed. The direct bandgap remains virtually constant under compression with a drop of only 0.01 eV around the phase transition. Interestingly, we have also found that light scattering by the polar nanoregions in the paraelectric phase is comparable to the dispersion due to ferroelectric microdomains in the ferroelectric state. Finally, we have obtained that the bulk modulus of the ferroelectric phase of Ca0.28Ba0.72Nb2O6 is B-0 = 222(9) GPa. Published by AIP Publishing.

Item Type: Journal Article
Creators:
CreatorsEmailORCIDORCID Put Code
Ruiz-Fuertes, J.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Gomis, O.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Segura, A.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Bettinelli, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Burianek, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Muehlberg, M.UNSPECIFIEDUNSPECIFIEDUNSPECIFIED
URN: urn:nbn:de:hbz:38-198574
DOI: 10.1063/1.5012111
Journal or Publication Title: Appl. Phys. Lett.
Volume: 112
Number: 4
Date: 2018
Publisher: AMER INST PHYSICS
Place of Publication: MELVILLE
ISSN: 1077-3118
Language: English
Faculty: Unspecified
Divisions: Unspecified
Subjects: no entry
Uncontrolled Keywords:
KeywordsLanguage
TEMPERATURE-DEPENDENCE; BARIUM; CRYSTALS; EDGEMultiple languages
Physics, AppliedMultiple languages
Refereed: Yes
URI: http://kups.ub.uni-koeln.de/id/eprint/19857

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