1. Multi-site occupancies and luminescence properties of cyan-emitting Ca9–xNaGd2/3(PO4)7:Eu2+phosphors for white light-emitting diodes
- Author
-
Liu, Shihua, Deng, Bin, Yang, Junhui, Liu, Jinhua, Chen, Jun, Zeng, Fanhua, Wang, Huanyou, Yu, Ruijin, and Zhang, Gongguo
- Abstract
Cyan-emitting Ca9NaGd2/3(PO4)7:Eu2+phosphors were synthesized via high temperature solid-state route. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) were used to verify the phase and morphology of the Ca9NaGd2/3(PO4)7:Eu2+(CNGP:Eu2+) phosphors. The as-obtained phosphor exhibits a broad excitation band of 250–420 nm, which is near the ultraviolet region. An intense asymmetric cyan emission at 496 nm corresponds to the 5d-4f transition of Eu2+. The multiple-site luminescent properties of Eu2+ions in CNGP benefit from versatile structure of β-Ca3(PO4)2compounds. The effective energy transfer distance is 5.46 nm (through the spectral overlap calculation), validating that the resonant energy migration type is via dipole–dipole interaction mechanism. Compared to the initial one at room temperature, the luminescent intensity of CNGP:Eu2+phosphor can maintain 77% as it is heated up to 420 K. A white light-emitting diode (WLED) with excellent luminescent properties was successfully fabricated. Moreover, the CIE chromaticity coordinates of fabricated WLED driven by changing current just change slightly.
- Published
- 2022
- Full Text
- View/download PDF