Multi-site occupancies and luminescence properties of cyan-emitting Ca9-xNaGd2/3(PO4)7:Eu 2+ phosphors for white light-emitting diodes

作者：Shihua, Liu; Deng, Bin^*; Yang, Junhui; Jinhua, Liu; Chen, Jun; Zeng, Fanhua; Wang, Huanyou; Yu, Ruijin; Zhang, Gongguo^*

来源：JOURNAL OF RARE EARTHS, 2022, 40(2): 243-252.

DOI：10.1016/j.jre.2021.01.007

• Phosphate
• Luminescence
• Eu2+ ion
• Ca9NaGd2/3(PO4)(7)
• Rare earths

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 beta-Ca-3(PO4)(2) com-pounds. 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.

• 单位
  西北农林科技大学