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arXiv · 2403.06713

Influence of Li-stoichiometry on electrical and acoustic properties and temperature stability of Li(Nb,Ta)O$_{3}$ solid solutions up to 900 {\deg}C

Éva Tichy-Rács·Stepan Hurskyy·Uliana Yakhnevych·Piotr Gaczyński·Steffen Ganschow·Holger Fritze·Yuriy Suhak
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Abstract

The current work is focused on the impact of the lithium stoichiometry on electrical conductivity, acoustic properties and high-temperature stability of single crystalline Li(Nb,Ta)O$_{3}$ at high temperatures. The crystals grown from Li-deficient melts were treated by the vapor transport equilibration (VTE) method, achieving near stoichiometric Li-content. It is shown, that the VTE-treated specimens generally exhibit lower conductivity at temperatures below 800 {\deg}C, which is attributed to the reduced number of Li-vacancies in near stoichiometric Li(Nb,Ta)O$_{3}$, provided that the Li-ion migration dominates the conductivity in this temperature range. Further, it is shown, that above 600-650 {\deg}C different mechanism increasingly contributes to the conductivity, which is consequently attributed to the electronic conduction. Further, it is shown that losses in LNT strongly increase above about 500 {\deg}C, which is interpreted to originate from conductivity-related relaxation mechanism. Finally, the thermal stability of Li(Nb,Ta)O$_{3}$ is evaluated by the measurement of the conductivity and resonance frequency as a function of time. It is found that during annealing at 700 {\deg}C for 350 hours, the resonance frequency of LiNbO$_{3}$ remains in a {\textpm} 100 ppm range of the initial value of 3.5 MHz.

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Éva Tichy-Rács, Stepan Hurskyy, Uliana Yakhnevych, Piotr Gaczyński, Steffen Ganschow, Holger Fritze, Yuriy Suhak. 2024-03-11. Influence of Li-stoichiometry on electrical and acoustic properties and temperature stability of Li(Nb,Ta)O$_{3}$ solid solutions up to 900 {\deg}C. https://arxiv.org/abs/2403.06713

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