Ferroelectric Hysteresis Measurement in the Lithium Niobate-Lithium Tantalate Single-Crystalline Family: Prospects for Lithium Niobate-Tantalate

Poling and structuring of ferroelectric domains form the basis for developing prospective applications using materials from the lithium-niobate (LN) family. Applications range from second harmonic generation to electro-optic modulators or surface acoustic wave devices. In the work presented here, hysteresis measurements are used as a standard method to quantitatively determine the poling properties of these ferroelectrics, including their spontaneous polarization Ps as well as their forward and reverse coercive fields Ec,+ and Ec,-. Systematic measurements that depend on parameters such as the ramp rate R of the applied poling voltage and the waiting time twait between domain inversions are investigated and compared between the congruent variants of LN, lithium tantalate (LT), their magnesium-doped analogues, and stoichiometric LN. For bulk magnesium-doped LN, for example, it is found that the resulting coercive field strongly depends on the speed of the voltage ramp, with Ec$E_{\text{c}}$ values ranging from 11 to 21 kV mm-1. These investigations are used as fundamental input for poling ferroelectric lithium niobate-tantalate solids (LNT), a system that offers a high potential for tuning the material parameters beyond what is possible for LN or LT. This article reports on the ferroelectric poling of various materials in the lithium niobate (LN) family using liquid electrodes. Different voltage ramp rates as well as waiting time between poling cycles are used to investigate the effect on the coercive fields. Additionally, poling current of the novel solid solution lithium-niobate-tantalate (LNT) is analyzed using multiple consecutive voltage pulses.image (c) 2024 WILEY-VCH GmbH