Spectroscopic Investigation of the Europium(3+) Ion in a New ZnY₄W₃O₁₆Matrix

A new Zn and Eu tungstate was characterized by spectroscopic techniques. This tungstate, of the formula ZnEu4W3O16, crystallized in the orthorhombic system and was synthesized by a solid-state reaction. It melts incongruently at 1330 degrees. The luminescent properties, including excitation and emission processes, luminescent dynamics, and local environments of the Eu3+ ions in ZnEu4W3O16 and ZnY4W3O16 : EU3+ diluted phases (1, 5, and 10 mol-% of Eu3+ ion) were studied basing on the f(6)- intraconfigurational transitions in the 250-720 nm spectral range. The excitation spectra of this system (lambda(em) 615 and 470 nm) show broad bands with maxima at 265 and 315 nm related to the ligand-to-metal charge-transfer (LMCT) states. The emission spectra under excitation at the O -> W (265 nm) and O -> Eu3+ (315 nm) LMCT states present the blue-green emission bands. the emission of tungstate groups mainly originate from the charge-transfer state of excited 2p orbitals of O2- to the empty orbitals of the central W6+ ions. On the other hand, in the emission of the Eu3+ ions, both the charge transfer from O2- to Eu3+ and the energy transfer from W6+ ions to Eu3+ are involved. The emission spectra under excitation at the F-7(0) -> L-5(6) transition of the Eu3+ ion (394 nm) of ZnY4W3O16 : Eu3+-diluted samples show narrow emission lines from the D-5(3), D-5(2), and D-5(1) emitting states. The effect of the active-ion (Eu3+) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented.