Photoluminescence and Color-Tunable Properties of Na<sub>4</sub>Ca<sub>4</sub>Mg<sub>21</sub>(PO<sub>4</sub>)<sub>18</sub>:Eu<sup>2+</sup>,Tb<sup>3+</sup>/Mn<sup>2+</sup> Phosphors for Applications in White LEDs
Dan Zhang, Xiangting Zhang, Zhengce An, Rujia Dong, Zhan Shi, Yanhua Song, Haifeng Zou
Abstract
Here, the crystal structure, phase analysis, site occupancy, and luminescence properties of NCMP:Eu2+,Tb3+,Mn2+ have been studied for the first time. Under 335 nm ultraviolet excitation, the NCMP:Eu2+ phosphors show narrow-band blue emission. In addition, we discuss the reason for a continuous red shift for the emission spectra of NCMP:xEu2+ by raising the x value. The efficient ET processes of Eu2+ → Tb3+ and Eu2+ → Mn2+ were investigated by the luminescence spectra and decay curves. The ET efficiencies reach 92.58% at y = 0.15 for NCMP:0.01Eu2+,yTb3+ and 99.85% at z = 0.15 for NCMP:0.01Eu2+,zMn2+ phosphors, respectively. The efficient energy transfer processes greatly improve the quantum efficiency, luminous intensity, and thermal stability. Bright green and red emissions can be realized through changing the related ratio of Eu2+, Tb3+, and Mn2+. In addition, the excellent performance of the prepared white LED lamps utilizing a 385 nm chip combined with our prepared NCMP:Eu2+,Tb3+/Mn2+ phosphors indicates that NCMP:0.01Eu2+,yTb3+ and NCMP:0.01Eu2+,zMn2+ phosphors can be potential green and red phosphors for white LEDs.