Żmojda Jacek, Kochanowicz Marcin, Miluski Piotr, Golonko Piotr, Baranowska Agata, Ragiń Tomasz, Dorosz Jan, Kuwik Marta, Pisarski Wojciech, Pisarska Joanna, Szal Renata, Mach Gabriela, Starzyk Bartosz, Leśniak Magdalena, Sitarz Maciej, Dorosz Dominik
Faculty of Electrical Engineering, Bialystok University of Technology, 45D Wiejska Street, 15-351 Bialystok, Poland.
Faculty of Mechanical Engineering, Bialystok University of Technology, 45C Wiejska Street, 15-351 Bialystok, Poland.
Materials (Basel). 2020 Jun 23;13(12):2817. doi: 10.3390/ma13122817.
Glass and ceramic materials doped with rare earth (RE) ions have gained wide interest in photonics as active materials for lasers, optical amplifiers, and luminescent sensors. The emission properties of RE-doped glasses depend on their chemical composition, but they can also be tailored by modifying the surrounding active ions. Typically, this is achieved through heat treatment (including continuous-wave and pulsed lasers) after establishing the ordering mechanisms in the particular glass-RE system. Within the known systems, silicate glasses predominate, while much less work relates to materials with lower energy phonons, which allow more efficient radiation sources to be constructed for photonic applications. In the present work, the luminescent and structural properties of germanate glasses modified with phosphate oxide doped with Eu ions were investigated. Europium dopant was used as a "spectroscopic probe" in order to analyze the luminescence spectra, which characterizes the changes in the local site symmetries of Eu ions. Based on the spectroscopic results, a strong influence of PO content was observed on the excitation and luminescence spectra. The luminescence study of the most intense D→F (electric dipole) transition revealed that the increase in the PO content leads to the linewidth reduction (from 15 nm to 10 nm) and the blue shift (~2 nm) of the emission peak. According to the crystal field theory, the introduction of PO into the glass structure changes the splitting number of sublevels of the D→F (magnetic dipole) transition, confirming the higher polymerization of fabricated glass. The slightly different local environment of Eu centers the results in a number of sites and causes inhomogeneous broadening of spectral lines. It was found that the local asymmetry ratio estimated by the relation of (D→F)/(D→F) transitions also confirms greater changes in local symmetry around Eu ions. Our results indicate that modification of germanate glass by PO allows control of their structural properties in order to functionalize the emissions for application as luminescent light sources and sensors.
掺杂稀土（RE）离子的玻璃和陶瓷材料作为激光、光放大器和发光传感器的活性材料，在光子学领域引起了广泛关注。稀土掺杂玻璃的发光特性取决于其化学成分，但也可以通过修饰周围的活性离子来进行调整。通常，这是在特定玻璃-稀土系统中建立有序机制后，通过热处理（包括连续波和脉冲激光）来实现的。在已知的系统中，硅酸盐玻璃占主导地位，而与具有较低能量声子的材料相关的研究工作则少得多，这些材料能够构建更高效的光子应用辐射源。在本工作中，研究了用掺杂Eu离子的氧化磷改性的锗酸盐玻璃的发光和结构特性。铕掺杂剂被用作“光谱探针”，以分析发光光谱，该光谱表征了Eu离子局部位置对称性的变化。基于光谱结果，观察到PO含量对激发光谱和发光光谱有强烈影响。对最强的D→F（电偶极）跃迁的发光研究表明，PO含量的增加导致发射峰的线宽减小（从15nm减小到10nm）和蓝移（约2nm）。根据晶体场理论，将PO引入玻璃结构会改变D→F（磁偶极）跃迁子能级的分裂数，证实了所制备玻璃的更高聚合度。Eu中心略微不同的局部环境导致了多个位置，并引起光谱线的非均匀展宽。发现通过（D→F）/（D→F）跃迁关系估计的局部不对称比也证实了Eu离子周围局部对称性的更大变化。我们的结果表明，用PO改性锗酸盐玻璃可以控制其结构特性，以便将发射功能化，用作发光光源和传感器。
