A promising novel red-emitting Eu3+-activated neodymium calcium phosphate phosphor with good thermal stability and excellent color purity for WLEDs

A series of Ca9Nd(PO4)(7):xEu(3+) (abbreviates as CNP:xEu(3+), where x varies from 0.1 to 0.5) phosphors were prepared via conventional solid-state reaction. The X-ray diffraction (XRD) data and Rietveld refinement suggested a successful preparation of CNP:xEu(3+) with no sign of impurities. The structure of CNP:Eu3+ belongs to a trigonal crystal system the same as that of beta-Ca-3(PO4)(2). Thus, Eu3+ ions should theoretically occupy the Ca sites in CNP. All CNP:xEu(3+) phosphors showed red emission under excitation in the near-ultraviolet (n-UV) range. The optimal dosage with the best luminescent performance was found at x = 0.3 with critical interaction radius (Rc) of 15.57 angstrom. The electric dipole-dipole interaction was suggested to be the reason that leads to concentration quenching. The relative luminous intensity of CNP:0.3Eu(3+) phosphor at 373 K can remain 70.4% of the initial value at room temperature (RT). The color purity of CNP:0.3Eu(3+) phosphor is 92.8%, which is much higher than many other red phosphors. A white light emitting diode (WLED) fabricated with CNP:Eu3+ exhibited correlated color temperature (CCT) of 4602 K and a high Ra of 74.7. The above results illustrate that Ca9Nd(PO4)(7):Eu3+ could serve as a promising red phosphor for n-UV WLEDs. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A series of CNP:xEu(3+) phosphors were prepared with different Eu(3+) doping concentrations, among which CNP:0.3Eu(3+) showed the best luminescent performance and high color purity. The WLED fabricated with this phosphor exhibited a medium correlated color temperature and a high Ra value.