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

• A novel red phosphor Ca 9 Nd(PO 4) 7 :Eu3+ was synthesized for the first time. • The occupation and crystalline structure of Ca 9 Nd(PO 4) 7 :xEu3+phosphors were thoroughly determined by DFF simulation and Rietveld refinement. • This phosphor can be efficiently excited by near-ultraviolet light to present intense red light emission. • The phosphor exhibits good property of thermal stability. • The WLED fabricated with Ca 9 Nd(PO 4) 7 :xEu3+ has shown superb color temperature and color purity. A series of Ca 9 Nd(PO 4) 7 :xEu3+ (abbreviates as CNP:xEu3+, 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:xEu3+ with no sign of impurities. The structure of CNP:Eu3+ belongs to a trigonal crystal system the same as that of β-Ca 3 (PO 4) 2. Thus, Eu3+ ions should theoretically occupy the Ca sites in CNP. All CNP:xEu3+ 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 Å. The electric dipole-dipole interaction was suggested to be the reason that leads to concentration quenching. The relative luminous intensity of CNP:0.3Eu3+ phosphor at 373 K can remain 70.4% of the initial value at room temperature (RT). The color purity of CNP:0.3Eu3+ 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 Ca 9 Nd(PO 4) 7 :Eu3+ could serve as a promising red phosphor for n-UV WLEDs. [Display omitted] [ABSTRACT FROM AUTHOR]