Local Site Symmetry Determination of Scheelite-Type Structures by Eu3+ Spectroscopy

SrWO 4: x %Eu 3+,Na + ( x = 0, 0.05, 0.5, and 5) have been prepared by the solid-state reaction method. Low temperature, high resolution emission and absorption spectroscopies have been employed to probe the local site symmetry of Eu 3+ ions occupied the Sr 2+ site in SrWO 4 with a doping concentration up to 5% using Na + as the charge compensation and, hence, to disapprove the formation of multicenters in the title compound containing trivalent lanthanide ions. The assignment of features in the 10 K visible emission spectra from 5 D 0,1 → 7 F J ( J = 0−4) multiplet terms and absorption spectrum from the ground-state level 7 F 0 → 5 D J ( J = 0−2) of SrWO 4:Eu 3+,Na + is consistent with the predicted number of bands for certain transitions based on the point group selection rules for the S 4 site symmetry. The incorporation of Na + together with Eu 3+ into the SrWO 4 lattice makes the vibronic bands associated with the 5 D 0 → 7 F J ( J = 0, 2, and 3) transitions shift to lower energy. The detailed spectroscopic interpretation conducted in this work serves as one of the few examples for Eu 3+ accommodating the S 4 site symmetry, which have only been rarely performed previously in the host of LiYF 4, and also gives insight into the assignment of lanthanide spectroscopy interpreted by forced electric and magnetic dipole selection rules.