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Structural Chemistry & Crystallography Communication
ISSN: 2470-9905
June 04-05, 2018
London, UK
Crystallography 2018
Page 34
3
rd
Edition of International Conference on
Advanced Spectroscopy,
Crystallography and Applications
in Modern Chemistry
T
he combination of the extraordinary physical properties
of lithium tantalate LiTaO3 (LT) offers a great potential for
applicationsinmodernopticsandphotovoltaics.Alargefractionof
such applications is based the defect chemistry. The congruently
growncompositionof LTusing theCzochralskymethodyields the
cation concentration ratios of [Li]/[Ta]=48.75/51.25. Li deficiency
suggests several possible configurations of a defect cluster in
congruent crystals, which guarantee charge neutrality. Several
intrinsic defect models have been considered in literature over
several decades. Here, using a combinational approach based
on DFT and solid-state NMR, we demonstrate that distribution
of electric field gradients (EFGs) on a 7Li site may be regarded
as a fingerprint of a specific defect configuration. The defect
structure in one of two congruent LT crystals after annealing was
identified experimentally and proved by the defect formation
energy consideration. We found that the defect cluster in this
crystal corresponded to the empty site model. The identification
of the defect structure in the second LT sample was more
challenging, implying the presence of extrinsic defects and an
inhomogeneous defect distribution. After thermal treatment,
hydrogen out-diffusion and homogeneous distribution of other
defects in both LT samples were observed in the NMR and FTIR
spectra. The approach of searching for the EFG fingerprints from
DFTcalculations in NMR spectra can be applied for identification
of the defect clusters in other complex oxides.
Recent Publications
1. V. A. Vizgalov, T. Nestler, L. A. Trusov, I. A. Bobrikov,
O.I. Ivankov, M.V. Avdeev, M. Motylenko, E. Brendler,
A. Vyalikh, D.C. Meyer, D. M. Itkis (2018) Enhancing
Lithium-IonConductivity inNASICONGlass-Ceramics
by Adding Yttria. Cryst. Eng. Comm., accepted DOI:
10.1039/C7CE01910F
2. A. Vyalikh, M. Zschornak, Th. Köhler, M. Nentwich, T.
Weigel, J. Hanzig, R. Zaripov, E. Vavilova, S. Gemming,
E. Brendler, D.C. Meyer (2018) Analysis of the defect
clusters in congruent lithium tantalate. Phys. Rev.
Identification of the defect clusters in
congruent lithium tantalate
Anastasia Vyalykh
TU Bergakademie Freiberg, Germany
Anastasia Vyalykh, Struct Chem Crystallogr Commun 2018, Volume 4
DOI: 10.21767/2470-9905-C1-004