Structure and Luminescent Properties of Niobium-Modified ZnO-B 2 O 3 :Eu 3+ Glass.

The effect of the addition of Nb 2 O 5 (up to 5 mol%) on the structure and luminescent properties of ZnO-B 2 O 3 glass doped with 0.5 mol% (1.32 × 10 22 ) Eu 2 O 3 was investigated by applying infrared (IR), Raman and photoluminescence (PL) spectroscopy. Through differential thermal analysis and density measurements, various physical properties such as molar volume, oxygen packing density and glass transition temperature were determined. IR and Raman spectra revealed that niobium ions enter into the base zinc borate glass structure as NbO 4 tetrahedra and NbO 6 octahedra. A strong red emission from the 5 D 0 level of Eu 3+ ions was registered under near UV (392 nm) excitation using the 7 F 0 → 5 L 6 transition of Eu 3+ . The integrated fluorescence intensity ratio R ( 5 D 0 → 7 F 2 / 5 D 0 → 7 F 1 ) was calculated to estimate the degree of asymmetry around the active ion, suggesting a location of Eu 3+ in non-centrosymmetric sites. The higher Eu 3+ luminescence emission observed in zinc borate glasses containing 1-5 mol% Nb 2 O 5 compared to the Nb 2 O 5 -free zinc borate glass evidences that Nb 2 O 5 is an appropriate component for modifying the host glass structure and improving the emission intensity.