Dysprosium doped niobium zinc fluorosilicate glasses: Interesting materials for white light emitting devices

Trivalent dysprosium doped niobium zinc fluorosilicate glasses modified with different Nb2O5/ZnF2 molar (M) ratios have been fabricated by the traditional melt-quenching technique and derived their structural, photoluminescence and decay properties using spectroscopic techniques. Induced structural modifications have been observed upon increasing content of Nb2O5. Maximum phonon energy of the glass matrix is found to be 1010 cm−1 from the Raman spectrum. The emission spectra of these glasses exhibit two intense bands at 480 and 570 nm besides a weak red emission at 650 nm. The decay profiles of Dy3+ ion for the 4F9/2 level exhibit a non-exponential behavior for all the glasses. The intrinsic lifetimes for the 4F9/2 level of Dy3+ ion have been determined by using the Inokuti-Hirayama model and are found to be 409, 366 and 325μs for the glasses with Nb2O5/ZnF2:10/30, 20/20 and 30/10 M ratios, respectively. The color coordinates have been evaluated from the emission spectra of the glasses and found that the glass with Nb2O5/ZnF2:30/10 M ratio appears near to the equal energy point. The correlated color temperature matches well to the summer sunlight region (4900-5600 K), indicating that the glasses could be a potential candidate for white light emitting devices.