Polarized Raman scattering spectra of the NaY(WO4)(2) (NYW) single crystal
have been measured. Its structure is described in the tetragonal space grou
p isomorphic to CaWO4 scheelite. The A(g), B-g, and E-g, spectra were made
and discussed in terms of factor group analysis. These spectra are compared
to those of monoclinic KY(WO4)(2) (KYW) single crystals whose structure di
ffers from the other crystal. The NYW unit cell comprises of the isolated W
O4 tetrahedra whereas the KYW structure is built from the WO6 octahedra joi
ned by WO2W double bonds and WOW single bridges. The Vibrational characteri
stics of the bridge bond systems are proposed. On this basis, the role of t
he vibronic transitions for the KYW crystal doped with Eu3+ ions is discuss
ed. (C) 2000 Elsevier Science B.V. All rights reserved.