A new type of phosphate-based phosphor Na3CsMg7(PO4)6:Eu2+/Mn2+ with high quantum efficiency and high thermostabitity

The Eu2+ ion, with the 4f(7)5d(1) electronic configuration, is one of the most important activated ions due to its symmetry-allowed 4f -> 5d electron transition. Herein, we successfully prepared a new type of blue phosphor, Na3CsMg7(PO4)(6):xEu(2+) (NCMP:xEu(2+)), in which Eu2+ occupies the Na+ sites of the host lattice. Under 395 nm light excitation, a broad emission band from 410 to 550 nm can be seen, peaking at 458 nm, due to the 5d -> 4f transition of Eu2+. Moreover, Eu2+ can be used as a sensitizer ion in an NCMP host. For co-doping phosphor NCMP:0.18Eu(2+)/0.4Mn(2+), both Eu2+ and Mn2+ emission bands can be seen using 395 nm as the excitation wavelength for the occurrence of Eu2+ -> Mn2+ charge transfer. The optimized concentration of Eu2+ for NCMP:xEu(2+) is x = 0.18, with high internal (IQE) and external quantum efficiencies (EQE) of 66.4% and 22.8%. The luminescence of NCMP:0.18Eu(2+) has high thermostability with 77.3% the intensity at 450 K compared to that at 300 K. Finally, a white illuminating lamp was produced using a 395 nm UV chip, blue phosphor NCMP:xEu(2+), green phosphor (Sr,Ba)(2)SiO4:Eu2+ and red phosphor CaAlSiN3:Eu2+ with CIE coordinates of (0.378, 0.369), color temperature (CCT) of 3971 K, and color rendering index (R-a) of 79.8.

Automated summary

The Eu2+ ion is an important activated ion due to its symmetry-allowed electron transition. A new type of blue phosphor, NCMP:xEu(2+), was successfully prepared. Eu2+ serves as a sensitizer ion in this phosphor. NCMP:xEu(2+) with optimal concentration of x = 0.18 exhibits high quantum efficiencies and thermostability. It can be used in the production of a white illuminating lamp.