Europium-doped boro-bismuth-tellurite glasses for multicolor phosphor applications

The glass system (50-x)B2O3-30Bi(2)O(3)-20TeO(2)-xEu(2)O(3) (x = 0, 0.1, 0.5, 1.0, 1.5, and 2.0 mol%) having been prepared using the conventional melt quenching method, is investigated in terms of physical, optical, and luminescence properties. The density of these glasses is measured and the corresponding molar volume is also calculated. The (alpha h nu)(1/n) versus h nu graph was plotted and it is well fitted to both direct (n = 1/2) and indirect (n = 2) band gaps. The direct and indirect band gap values range from 2.57 to 2.94 eV and 1.74 to 2.58 eV, respectively. The Urbach energy of the glass system was calculated to have values ranging from 0.29 to 0.62 eV. Yellow, orange, and red emissions have been observed through photoluminescence (PL) spectroscopy excited at 464 nm and the obtained multicolor emissions have been demonstrated according to the Commission International de l'Eclairage de France 1931 standards. The results of PL studies indicated the possibility towards the development of multicolor phosphor applications.