Tunable photoluminescence properties of Ca8NaLa(PO4)6F2:Eu2+,Mn2+ phosphor under UV excitation

A series of Eu2+ and Mn2+ coactivated Ca8NaLa(PO4)(6)F-2 (CNLF) phosphors have been synthesized by a combustion-assisted synthesis method. The investigation revealed that Ca8NaLa(PO4)(6)F-2 crystallized in a hexagonal crystal system with the space group P6(3)/m (176). The Eu2+ activated phosphors can be efficiently excited in the range of 270-400 nm and give intense blue emission peaking at 451 nm. By codoping the Eu2+ and Mn2+ ions into the CNLF host and singly varying the doping content of the Mn2+ ion, tunable colors from blue to white and eventually to yellow are obtained in CNLF:Eu2+,Mn2+ phosphors under the irradiation of 330 nm. The energy transfer from Eu2+ to Mn2+ in CNLF:Eu2+,Mn2+ has been demonstrated to be a resonant type via a dipole-dipole mechanism and the critical distance of energy transfer from Eu2+ to Mn2+ was estimated to be about 11.9 angstrom. The investigation indicates that the obtained samples might have potential application in white LEDs. (C) 2014 Elsevier Ltd. All rights reserved.