A Sm3+-doped YGa1.5Al1.5(BO3)4 (abbreviated as YGAB) phosphor was synthesized via a solid-state reaction with mechanical activation assistance in a high-energy density stirred bead mill. The samples were characterized by laser particle size analysis, specific surface area analysis, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and fluorescence spectroscopy. In addition, the photoluminescence characteristics, luminescence decay, thermal stability, and LED application of the phosphors were also investigated. The results show that the mechanical activation of mixed raw materials before calcination can reduce the particle size and the activation energy of crystallization, resulting in the formation of the YGAB crystal phase at a lower calcination temperature. The mechanical activation in grinding can accelerate the subsequent solid-phase reaction, make Sm3+ ions more easily diffuse into the YGAB lattice, and improve the crystal structure of the synthesized phosphor, thus enhancing the optical properties of the phosphor. According to the photoluminescence emission (PL) and excitation (PLE) spectra, Sm3+ doped in the YGAB lattice can provide an efficient emission under 405 nm excitation. The optimum doping concentration of Sm3+ ions is 0.03 mol%. The optimum photoluminescence intensity, quantum yield, and fluorescence lifetime of the phosphor synthesized from mixed raw materials ground for 45 min can be obtained. The temperature-dependent PL spectra show that the emission intensity of the YGAB:0.03Sm3+ phosphor at 425 K is 84.7% of its initial intensity at room temperature. It is indicated that the YGAB:0.03Sm3+ phosphor synthesized could be used as one of the promising LED lighting materials.
Ye Ming-Yu,Zhang Ming-Xuan,Xu Qiao-Fei,Xu Han,Long La-Sheng,Zheng Lan-Sun
Lanthanide luminescent materials with high quantum yield and thermal stability are of key importance for their practical application. Here we report crystal structures and luminescent properties of [Eu(pfbz) 2 (phen)Cl] ( 1 ) and [Tb(pfbz) 2 (phen)Cl] ( 2 ) (pfbz = Pentafluorobenzoate). Single-crystal analysis reveals that both 1 and 2 crystallize in a polar space group of Cmc 2 1 . Investigation on their luminescent properties indicates that the solid-state quantum yields of 1 and 2 are 97.7% and 90.7%, respectively, while their efficiency of the sensitization process is as high as 100%, revealing that polar structures are more favorable to obtain high quantum yields. Thermogravimetric analysis reveals that both 1 and 2 can be stable up to 240 °C. More importantly, temperature-dependent luminescent spectra of 1 indicate its luminescent intensity at 612 nm only decreased by 5% from room temperature to 373 K, whereas at 373 K, its luminescent intensity remains almost constant for 36 h. Considering that 1 represents the highest quantum yield among known Eu-coordination polymers and its performance as the LED material is better than that of commercially widely used luminescent materials of (Sr,Ca)AlSiN 3 :Eu (630 nm) and (Sr,Ca)AlSiN 3 :Eu (640 nm), the present work provides an excellent substitute for commercial LED materials.
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