Structural and spectroscopic characteristics of Eu3+-doped tungsten phosphate glasses

Tungsten based phosphate glasses are interesting non-crystalline materials, commonly known for photochromic and electrochromic effects, but also promising hosts for luminescent trivalent rare earth ions. Despite very few reports in the literature, association of the hosts functionalities with the efficient emissions of the dopant ions in the visible and near-infrared spectra could lead to novel applications. This work reports the preparation and characterization of glasses with the new composition 4(Sb2O3)96-x(50WO(3) 50NaPO(3))xEu(2)O(3) where x = 0, 0.1, 0.25, 0.5 and 1.0 mol%, obtained by the melt quenching technique. The glasses present large density (similar to 4.6 g cm(-3)), high glass transition temperature (similar to 480 degrees C) and high thermal stability against crystallization. Upon excitation at 464 nm, the characteristic emissions of Eu3+ ions in the red spectral region are observed with high intensity. The Judd-Ofelt intensity parameters Omega(2) = 6.86 x 10(-20), Omega(4) = 3.22 x 10(-20) and Omega(6) = 8.2 x 10(-20) cm(2) were calculated from the emission spectra and found to be higher than those reported for other phosphate glass compositions. An average excited state lifetime value of 1.2 ms, was determined by fitting the luminescence decay curves with single exponential functions and it is comparable or higher than those of other oxide glasses. (C) 2015 Elsevier B.V. All rights reserved.