Photoluminescence investigation of trivalent rare earth activated Na3Pb2(SO4)3Cl phosphors for solid state lighting

In this paper we report the photoluminescence (PL) characteristics of Dy3+, Sm3+, Eu3+ and Tb3+ doped Na3Pb2(SO4)3Cl phosphors prepared by wet chemical method. Prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), color co-ordinates and photoluminescence (PL) properties. The emission spectra of Na3Pb2(SO4)3Cl:Dy3+ phosphor show the characteristic emission of Dy3+ ions peaking at 478 nm and 573 nm (λex = 390 nm), owing to transitions of 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 receptively. Under 396 nm excitation the Na3Pb2(SO4)3Cl:Eu3+ phosphor shows emission at 594 nm and 616 nm due to 5D0 → 7F1 and 5D0 → 7F2 transitions of Eu3+ ions respectively. When Na3Pb2(SO4)3Cl:Tb3+ phosphor was excited by 380 nm, the emission spectrum showed intense green band at 545 nm due to 5D4 → 7F5 transition in Tb3+ ion. The PL emission spectrum of Na3Pb2(SO4)3Cl:Sm3+ phosphors by 405 nm excitation gave an emission at 562 nm (4G5/2 → 6H5/2), 598 nm (4G5/2 → 6H7/2) and 643 nm (4G5/2 → 6H9/2). The CIE color coordinates indicated that all the above phosphors were suitable as a white light-emitting phosphor. SEM studies of the phosphors show that grain size of the powders prepared by the wet chemical method is about ten micrometers range. From the obtained results it can be concluded that Dy3+, Sm3+ Eu3+ and Tb3+ doped Na3Pb2(SO4)3Cl phosphors are potential candidates for solid state lighting applications in green technology.