Zhao Junjie, Xu Xiuxia, Li Pengcheng, Li Xinyue, Chen Daqin, Qiao Xvsheng, Du Jincheng, Qian Guodong, Fan Xianping
State Key Laboratory of Silicon Materials & School of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China.
Department of Materials Science and Engineering , University of North Texas , Denton , Texas 76203 , United States.
J Phys Chem B. 2019 Apr 4;123(13):3024-3032. doi: 10.1021/acs.jpcb.9b01674. Epub 2019 Mar 21.
Oxyfluoride glass-ceramics with RF or NaRF (R: rare earth elements) nanocrystals are considered as favorable hosts for luminescence applications. In this work, we utilized large-scale molecular dynamics (MD) simulations with effective partial charge potentials to study a series of oxyfluoride glasses that are of interest to the precipitation of RF or NaRF nanocrystals as previous experiment results suggested. The results show that phase separation exists in all glass compositions with fluoride-rich regions made up of R, Na, and F and oxide-rich regions consisting of aluminosilicate networks. These fluoride-enriched regions can serve as the precursor for RF, cubic and hexagonal NaRF, and NaF crystal precipitation. The results also confirm that the concentration of Na in the fluoride phase plays a key role in determining the crystal phases (RF, NaRF, or NaF) and crystal structure (cubic vs hexagonal NaRF) to be precipitated. Consequently, this study shows that MD simulations with effective potentials can fill the gap in the structural understanding of oxyfluoride glass and provide insights into atomic scale information of the phase separation behavior that is useful in predicting the potential crystal types in oxyfluoride glass. When coupled with experimental validations, these simulations can expedite the exploration of novel luminescent oxyfluoride glass ceramics.
含有RF或NaRF（R：稀土元素）纳米晶体的氧氟化物玻璃陶瓷被认为是发光应用的理想基质。在这项工作中，我们利用具有有效部分电荷势的大规模分子动力学（MD）模拟，研究了一系列氧氟化物玻璃，正如先前的实验结果所表明的，这些玻璃对于RF或NaRF纳米晶体的析出具有研究价值。结果表明，所有玻璃成分中均存在相分离，富氟区域由R、Na和F组成，富氧化物区域由铝硅酸盐网络构成。这些富氟区域可作为RF、立方相和六方相NaRF以及NaF晶体析出的前驱体。结果还证实，氟化物相中Na的浓度在决定析出的晶体相（RF、NaRF或NaF）和晶体结构（立方相六方相NaRF）方面起着关键作用。因此，本研究表明，具有有效势的MD模拟可以填补对氧氟化物玻璃结构理解的空白，并提供关于相分离行为的原子尺度信息，这有助于预测氧氟化物玻璃中潜在的晶体类型。当与实验验证相结合时，这些模拟可以加速新型发光氧氟化物玻璃陶瓷的探索。
