Dresden 2026 – scientific programme

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FM: Fachverband Funktionsmaterialien

FM 14: Focus Session: Materials Research in Polar Oxides – From Domain Engineering to Photonic and Electronic Devices II

FM 14.3: Talk

Wednesday, March 11, 2026, 15:30–15:45, BEY/0138

Single crystal growth of stoichiometric lithium tantalate — •Sebastian Inckemann, Roberts Blukis, Angélique Hoffmann, Matthias Bickermann, and Steffen Ganschow — Leibniz-Institut für Kristallzüchtung, Max-Born-Straße 2, 12489 Berlin, Germany

A material isomorphous to the intensively investigated lithium niobate (LiNbO3, LN) that has the same inherent non-stoichiometry is lithium tantalate (LiTaO3, LT). Despite similar characteristics to LN, the properties of LT are significantly less studied, even though there are notable differences that favor the use of LT in certain applications. Of special interest is the investigation of stoichiometric LT (sLT) compared to congruent LT (cLT), as the lithium deficiency in cLT causes a high concentration of defects (Kim et al., 2001). Literature describes multiple methods to achieve stoichiometric LN single crystals, exemplary via the double crucible method. However, the growth method reporting a crystal composition closest to the stoichiometric ratio is the growth via the flux method (Polgár et al., 2002). Due to the similarities between LN and LT an analogous approach is the most promising, with the use of K₂O as a solvent showing the best results in the case of LN (Polgár et al., 1997). To ensure an efficient single crystal growth in this system, knowledge about the Li₂O-K₂O-Ta₂O₅ phase diagram is vital (Mühlberg et al., 2008). As there is no literature regarding this phase diagram, this presentation will present our current progress by combining DTA, PXRD and SEM measurements. Furthermore, results regarding the single crystal sLT growth attempts will be presented.

Keywords: Single Crystal Growth; Phase Diagram; Stoichiometric Lithium Tantalate