Berlin 2015 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 11: Small Polarons in LiNbO3
DF 11.3: Talk
Wednesday, March 18, 2015, 10:10–10:30, EB 133C
Direct measurement of the Fe-polaron deformation in Fe:LiNbO3 — •Marco Bazzan, Andrea Sanson, Annamaria Zaltron, Nicola Argiolas, and Cinzia Sada — Università di Padova, Padova, Italy
In this talk some recent experimental results on the structural characterization of the Fe small polarons in iron doped lithium niobate will be discussed.
On one hand, High Resolution X-rays Diffraction shows a bulk average strain appearing in the crystal as a consequence of the reduction process Fe3+ + e → Fe2+. It will be shown that this effect has to be attributed to strain dipoles located at the Fe centers, with a magnitude dependent on the charge state of the Fe ion.
These findings are definitely confirmed using X-Ray Absorption Fine Structure Spectroscopy at the Fe edge: upon oxidation or reduction the oxygen cage surrounding the Fe impurity is more or less compressed with respect to the regular LiNbO3 structure.
Those results give a quantitative picture of the polaronic lattice deformation associated to the localization of an electronic charge at the Fe impurity.