Regensburg 2019 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Postersession KFM

KFM 14.23: Poster

Wednesday, April 3, 2019, 16:00–18:30, Poster C

Temperature-dependent fs-pulse-induced luminescence of lithium niobate — •Janina Ringel, Andreas Krampf, Simon Messerschmidt, and Mirco Imlau — School of Physics, Osnabrueck University, Barbarastr. 7, 49076 Osnabrueck, Germany

Temperature-dependent luminescence of lithium niobate (LN) after fs-pulse illumination is investigated over a large temperature range, i.e., from 10–300 K. As the luminescence intensity decreases exponentially above 100 K, a continuous broadening and shift of the peak position can be observed. Therefore, self-trapped excitons which are accounted for the low-temperature luminescence of LN (Blasse, Mat. Chem. Phys. 14, 1986) are present at room temperature as well. However, above 200 K an unexpected deviation of the temperature-dependent emission peak from the well-known Varshni-behavior is found. Expressions based on phonon emission and absorption governed by Bose-Einstein statistical factors fail to describe the observed dependency of the peak position and halfwidth, as well (Viña, Phys. Rev. B 30 (4), 1984). We therefore discuss the presence of a second luminescing center.
Additional time-resolved luminescence data are presented. The decay time decreasing exponentially above 100 K limits the maximum temperature to 180 K. We show that a total of three different decay dynamics are present in heavily Mg-doped samples. Two of them, recently investigated (Kämpfe, Phys. Rev. B 93, 2016), are lying in the µs–ms and second range, respectively. Here, both are observed for a larger temperature range. Financial support by the DFG (IM37/11-1, INST 190/165-1 FUGG) is gratefully acknowledged.