SKM 2023 – scientific programme
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 13: Polar Oxide Crystals and Solid Solutions I
KFM 13.4: Talk
Thursday, March 30, 2023, 11:00–11:20, POT 106
Acoustic loss in Lithium Niobate-Lithium Tantalate solid solutions with different Nb/Ta ratios at temperatures up to 900°C — •Uliana Yakhnevych1, Claudia Kofahl2, Stepan Hurskyy1, Steffen Ganschow3, Yuriy Suhak1, Harald Schmidt2, and Holger Fritze1 — 1Institute of Energy Research and Physical Technologies, Clausthal University of Technology, Germany — 2Institute of Metallurgy, Clausthal University of Technology, Germany — 3Leibniz-Institut für Kristallzüchtung, Berlin, Germany
Lithium niobate-lithium tantalate solid solutions (LNT) are poorly studied materials in modern materials science, which must be seen in the light that they can combine the advantages of the edge compounds lithium niobate (LN) and lithium tantalate (LT). These crystals are expected to exhibit high piezoelectric coefficients and thermal stability. This work focuses on comparing the Q-factor of LN, LT, and LNT as well as on the analysis of loss contributions in samples. Electromechanical losses of the samples were determined using two different approaches, namely noncontacting resonant ringdown spectroscopy and resonant piezoelectric spectroscopy using Pt electrodes. LNT thickness-shear mode (TSM) acoustic resonators exhibit significantly lower loss than LN. The study of the acoustic loss in LNT resonators operated in the TSM showed strong frequency dependent loss increases at temperatures above 450°C. The loss was modelled using independent materials data. Based on the modelling, the above-mentioned loss above 450°C is associated with a conductivity-induced piezoelectric/carrier relaxation mechanism governed by Li migration.