Leaño Julius L, Mariano Carl Osby M, Huang Wen-Tse, Mahlik Sebastian, Lesniewski Tadeusz, Grinberg Marek, Sheu Hwo-Shuenn, Hu Shu-Fen, Liu Ru-Shi
Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.
Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei 10617, Taiwan.
ACS Appl Mater Interfaces. 2020 May 20;12(20):23165-23171. doi: 10.1021/acsami.0c07345. Epub 2020 May 8.
The systematic substitution of Ba in the Sr site of Sr[MgAlN]:Eu generates a deep-red-emitting phosphor with enhanced thermal luminescence properties. Gas pressure sintering (GPS) of all-nitride starting materials in Molybdenum (Mo) crucibles yields pure-phase red-orange-colored phosphors. Peaks in the synchrotron X-ray diffraction (SXRD) data show a systematic shift toward smaller angles due to the introduction of the larger Ba cation in the same crystal structure. The photoluminescence property reveals that Ba substitution shifts the original emission wavelength of Sr[MgAlN]:Eu (625 nm) toward ∼690 nm for Ba[MgAlN]:Eu. Thermal stability measurement of SrBa[MgAlN] indicates a systematic increase in stability from = 0 to = 1. X-ray absorption near-edge spectroscopy (XANES) results demonstrate the coexistence of Eu and Eu. The red-shift and the enhanced thermal stability reveals that the distance of the emitting 5 level to the conduction band of Ba[MgAlN]:Eu is large. The ionic size mismatch of Eu occupying a Ba site reduces the symmetry, thereby further splitting the degenerate emitting 5 level and lowering the energy of the emitting center. The development of deep-red phosphors emitting at 670-690 nm ( = 0.8-1.0) offers possible candidates for plant lighting applications.
在Sr[MgAlN]:Eu的Sr位点上系统地用Ba进行取代，可生成一种具有增强热发光性能的深红色发光荧光粉。在钼（Mo）坩埚中对全氮化物原料进行气压烧结（GPS）可得到纯相红橙色荧光粉。同步加速器X射线衍射（SXRD）数据中的峰显示，由于在相同晶体结构中引入了较大的Ba阳离子，峰向较小角度发生了系统偏移。光致发光特性表明，对于Ba[MgAlN]:Eu，Ba取代使Sr[MgAlN]:Eu的原始发射波长（625 nm）向~690 nm移动。SrBa[MgAlN]的热稳定性测量表明，稳定性从x = 0到x = 1有系统地增加。X射线吸收近边光谱（XANES）结果证明了Eu²⁺和Eu³⁺的共存。红移和增强的热稳定性表明，Ba[MgAlN]:Eu的发射5d能级与导带之间的距离较大。Eu占据Ba位点时的离子尺寸不匹配降低了对称性，从而进一步分裂简并的发射5d能级并降低发射中心的能量。发射波长在670 - 690 nm（x = 0.8 - 1.0）的深红色荧光粉的开发为植物照明应用提供了可能的候选材料。
