Wydział Chemii

Elżbieta Tomaszewicz

Małgorzata Guzik

Joanna Cybińska

Janina Legendziewicz

2009

Helvetica Chimica Acta

92

2274-2290

10.1002/hlca.200900151

Naukowa

Angielski

Artykuł

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°. 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 f⁶-intraconfigurational transitions in the 250–720 nm spectral range. The excitation spectra of this system (λ_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 ⁷F₀→⁵L₆ transition of the Eu³⁺ ion (394 nm) of ZnY₄W₃O₁₆ : Eu³⁺ diluted samples show narrow emission lines from the ⁵D₃, ⁵D₂, and ⁵D₁ emitting states. The effect of the active-ion (Eu³⁺) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented.

https://doi.org/10.1002/hlca.200900151

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