Effect dopant concentration on the photoluminescent properties of SrWO4:Eu 3+

Abstract

Inorganic materials doped with trivalent rare earth ions (R3+) have been extensively applied as luminescent phosphors because exhibit high emission intensities. Alkaline earth tungstates have shown intrinsic luminescence mainly attributed to the ligand to metal charge transfer (LMCT) band, which the energy can be transferred to emitting centers as the R 3+ ions. In this work, the SrWO4 matrix doped with different concentrations of Eu3+ were synthesized by a soft chemistry method using a simple precipitation without any thermal treatment. The X-ray powder diffraction patterns (Fig. 1) indicated that the main component is the Scheelite phase with high crystallinity. Besides, the crystallite size data of the samples, calculated by using the Scherrer formula were ca. 30 nm. The SEM micrographs were obtained, showing high homogeneous profile for the different concentrations. The excitation spectra showed both the OW LMCT band centered at 290 nm and the 4f6 intraconfigurational transitions of Eu3+ ion. However, the emission spectra of the Eu3+(5 %) ion doped in SrWO4 matrix showed the only the 5D0 7 F0-4 transitions of europium ion with similar spectral profiles (Fig. 2) under excitations at 290 (LMCT band) and 393 nm (7 F0 5 L6). The 5D0 7 F2 transition presents highest emission intensity. Furthermore the absence of LMCT broad emission band of SrWO4 indicating the efficient energy transfer from the matrix to the Eu3+ emitting center. The SrWO4:Eu3+ nanocrystalline phosphors were efficiently prepared by a simple method with high crystallinity. This luminescent material showed an efficient energy transfer from the LMCT band to the Eu3+ ion, suggesting that these doped systems are promising red emitting nanophosphors.