New yellow-emitting Whitlockite-type structure Sr(1.75)Ca(1.25)(PO4)2:Eu(2+) phosphor for near-UV pumped white light-emitting devices.
New compound discovery is of interest in the field of inorganic solid-state chemistry. In this work, a whitlockite-type structure Sr1.75Ca1.25(PO4)2 newly found by composition design in the Sr3(PO4)2-Ca3(PO4)2 join was reported. Crystal structure and luminescence properties of Sr1.75Ca1.25(PO4)2:Eu(2+) were investigated, and the yellow-emitting phosphor was further employed in fabricating near-ultraviolet-pumped white light-emitting diodes (w-LEDs). The structure and crystallographic site occupancy of Eu(2+) in the host were identified via X-ray powder diffraction refinement using Rietveld method. The Sr1.75Ca1.25(PO4)2:Eu(2+) phosphors absorb in the UV-vis spectral region of 250-430 nm and exhibit an intense asymmetric broadband emission peaking at 518 nm under λex = 365 nm which is ascribed to the 5d-4f allowed transition of Eu(2+). The luminescence properties and mechanism are also investigated as a function of Eu(2+) concentration. A white LED device which is obtained by combining a 370 nm UV chip with commercial blue phosphor and the present yellow phosphor has been fabricated and exhibit good application properties.
School of Materials Science and Technology, China University of Geosciences (Beijing) , Beijing, 100083, China.
Haipeng
H
Ji
Zhaohui
Z
Huang
Zhiguo
Z
Xia
Maxim S
MS
Molokeev
Victor V
VV
Atuchin
Minghao
M
Fang
Saifang
S
Huang