Extraction Pyrolytic Synthesis and Luminescent Properties of Double Tungstates La2W2O9 Doped with Europium and Terbium

Inorganic materials based on lanthanum tungstates doped with optically active lanthanide ions exhibit intense and broad emission spectra. In view of the influence of synthesis methods on the morphology, particle size, exact optimal concentration ratio of doping ions, and, hence, luminescence characteristics of the dopants, the search for efficient methods of synthesis is in progress. This study demonstrates the possibility of obtaining double lanthanum tungstates α-La2W2O9, α-La2–xEuxW2O9, α-La2–xTbxW2O9, and La1.95–xEu0.05TbxW2O9 (х = 0.0075, 0.01, 0.02, 0.03, 0.04, 0.05, 0.075, 0.10) under milder conditions of extraction-pyrolytic synthesis. The structure of the triclinic α-La2W2O9 phase does not change on doping with Eu3+ and Tb3+ ions. Compounds La1.95–xEu0.05TbxW2O9 exhibit luminescence in the 450 to 725 nm range (λeх = 308 nm) comprising 5D4–7Fj (j = 1–6) transition bands for Tb3+ and 5D0–7Fj (j = 0–4) transition bands for Eu3+. The spectral patterns indicate the invariability of the Eu3+ local environment in the tungstates La2–xEuxW2O9 and La1.95–xEu0.05TbxW2O9.