Wlodarczyk Damian, Bulyk Lev-Ivan, Berkowski Marek, Glowacki Michal, Kosyl Katarzyna M, Kaczmarek Slawomir M, Kowalski Zbigniew, Wittlin Aleksander, Przybylinska Hanka, Zhydachevskyy Yaroslav, Suchocki Andrzej
Institute of Physics , Polish Academy of Sciences , Al. Lotnikow 32/46 , 02-668 Warsaw , Poland.
Institute of Physics , West Pomeranian University of Technology in Szczecin , Al. Piastow 17 , 70-310 Szczecin , Poland.
Inorg Chem. 2019 May 6;58(9):5617-5629. doi: 10.1021/acs.inorgchem.8b03606. Epub 2019 Apr 18.
We report detailed optical studies of BaWO:Ce and BaWO:Ce,Na single crystals. The material does not emit any luminescence at ambient pressure under near-UV (325 nm) excitation. Efficient green light is emitted only at high pressure (HP) and low temperature (LT). The luminescence is of excitonic character, since the lowest Ce 5d level is degenerate with the conduction band also under hydrostatic pressures. To explain these phenomena, absorption measurements were made together with powder X-ray diffraction (XRD) and confocal micro-Raman and Fourier transform infrared (FTIR) spectroscopy. Raman experiments confirm the existence of a metastable phase, induced by certain nonhydrostatic conditions, before the reversible transition at a high-pressure range above 9 GPa, where efficient photoluminescence (PL) occurs. Although the phase transition is reversible, it proceeds with a prominent hysteresis observed in luminescence and Raman experiments. FTIR focuses on the existence of Ce multisites observed during LT measurements.
我们报告了对BaWO₄:Ce和BaWO₄:Ce,Na单晶的详细光学研究。该材料在近紫外（325 nm）激发下的常压环境中不发射任何发光。仅在高压（HP）和低温（LT）下才会高效发射绿光。这种发光具有激子特性，因为在静水压力下最低的Ce 5d能级也与导带简并。为了解释这些现象，我们结合粉末X射线衍射（XRD）、共焦显微拉曼光谱和傅里叶变换红外（FTIR）光谱进行了吸收测量。拉曼实验证实，在高于9 GPa的高压范围内发生可逆转变之前，由某些非静水条件诱导存在亚稳相，在此范围内会出现高效光致发光（PL）。尽管相变是可逆的，但在发光和拉曼实验中观察到它伴随着明显的滞后现象。FTIR关注低温测量期间观察到的Ce多位置的存在情况。
