Synthesis, structural and luminescent properties of Lu2W3O12:Eu3+ concentration series

The lack of sufficient exploration of lutetium tungstate doped with europium ions has led to significant interest in terms of structure formation and luminescence properties. The series of (Lu1-xEux)2W3O12 powders (x = 0.01–1) was synthesized using an improved modified Pechini method (with additional gel treatment) and compared with the previously developed modified Pechini technique. The phase composition of the prepared samples was studied by X-Ray diffraction. XRD analysis verified the orthorhombic structure of the powders (for 1–50 at.% Eu3+) and the monoclinic structure (for 75 and 100 at.% Eu3+). The results also showed the occurrence of phase splitting and formation two Lu2W3O12 orthorhombic structures for Eu3+ concentrations above 40 at.% and two Eu2W3O12 monoclinic phases above 75 at.% Eu3+ without any impurities. Eu3+ doping concentration significantly affects the structural changes leading to different formations of the shape and size of the particles, the positions of the vibrational states, the luminescence characteristics, and the lifetime of the samples. The optimal doping concentration of Eu3+ is found to be 50 and 75 at.% for host and direct excitation, respectively. The observed 5D0 lifetime gradually decreases from 0.47 ms to 0.1 ms with the growth of the Eu3+ ions number.