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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 18: Materials Research in Polar Oxides: Perspectives for Optics & Electronics
KFM 18.2: Talk
Thursday, March 20, 2025, 16:00–16:15, H9
Gray tracks in KTiOPO4 from DFT calculations — •Adriana Bocchini, Uwe Gerstmann, and Wolf Gero Schmidt — Department Physik, Universität Paderborn, 33095 Paderborn, Germany
Ferroelectric KTiOPO4 (KTP) is commonly applied in (nonlinear) optical devices. However, the irradiation with high-intensity laser light or the application of strong electric fields triggers the formation of detrimental gray tracks [1], the microscopic origin of which is usually attributed to Ti3+ centers (i.e., reduced titanium atoms) charge compensating for oxygen vacancies [2]. In this study, we use DFT routines to further clarify the gray-tracking mechanisms by systematically model oxygen-vacancy related Ti3+ centers in application-relevant environments, i.e., potassium vacancies and rubidium dopants. We find that the only thermally stable [2] Ti3+ center forms close, but not adjacent the oxygen vacancy itself. In addition, displaced potassium ions provide the stabilizing forces, whereas potassium interstitials rather than oxygen vacancies alone appear to be directly related to gray tracks. For this we suggest that the current gray-tracking model has to be partially revised. [3]
[1] M. Roth, in Springer Handbook of Crystal Growth, Chap 20, 691 (2010, Berlin, Heidelberg)
[2] S. D. Setzler, et al., J. Condens. Matter Phys. 15, 3969 (2003)
[3] A. Bocchini, et al., submitted to Phys. Rev. B
Keywords: KTiOPO4; Gray Tracks; DFT; Hyperfine structure