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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 9: Focus: Polar oxide crystals and solid solutions
KFM 9.5: Vortrag
Mittwoch, 18. März 2020, 11:00–11:20, TOE 317
Oxygen transport in single crystalline Li(Nb,Ta)O3 solid solutions at high temperatures — •Bujar Jerliu1, Yuriy Suhak1, Dmitry Roshchupkin2, Boris Red'kin2, Steffen Ganschow3, Harald Schmidt1, Günter Borchardt1, Klaus Dieter Becker4 und Holger Fritze1 — 1Clausthal University of Technology, Goslar, Germany — 2Institute of Microelectronics Technology and High Purity Materials, RAS, Chernogolovka, Russia — 3Leibnitz Institute for Crystal Growth, Berlin, Germany — 4Braunschweig University of Technology, Braunschweig, Germany
Single crystalline lithium niobate-tantalate (LiTaxNb(1-x)O3, LNT) solid solutions are expected to overcome the problems of thermal instability of lithium niobate (LiNbO3, LN) and low Curie temperature of lithium tantalate (LiTaO3, LT). This work focuses on study of transport mechanisms in LNT crystals with different Nb/Ta ratio, grown by the Czochralski technique. The oxygen transport kinetics are investigated in the temperature range from 850°C to 1200°C using the stable isotope 18O as the tracer. Subsequently, the diffusion profiles are acquired by secondary ion mass spectrometry. The oxygen diffusion coefficients for LiNb0.88Ta0.12O3 single crystals at annealing temperatures of 850°C and 1000°C equal about 4.5 x 10-18 m2/s and 1.5 x 10-16 m2/s, respectively. Our previous 18O tracer experiments carried out on stoichiometric LN revealed a local maximum on the depth profiles, which was explained by the Li-diffusion out of the crystal structure. Such a maximum is not observed for LNT compound, which could possibly indicate an improved stability of the material.