Physical, vibrational, optical and luminescence investigations of Dy³⁺-doped yttrium calcium silicoborate glasses for cool white LED applications

The Dy³⁺-doped yttrium calcium silicoborate glasses of composition of 25Y₂O₃ + 10CaO + 10SiO₂ + (55-x)B₂O₃ + x Dy₂O₃, where x = 0.05, 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%, have been synthesized and are characterized through optical, photoluminescence and X-ray induced luminescence properties. The Judd-Ofelt model has been adopted to evaluate the radiative properties of the ⁴F_9/2 → ⁶H_J (J = 15/2, 13/2 and 11/2) emission transitions. The concentration quenching effect of Dy³⁺ ion concentration on the emissions from the ⁴F_9/2 excited level is discussed in details. The luminescence decay curves of the ⁴F_9/2 level transform from exponential to non-exponential nature for higher Dy³⁺ ion concentration. The yellow to blue (Y/B) intensity ratio, CIE Chromaticity coordinates and correlated color temperatures (CCT) were calculated from the emission spectra and were found that they fall in yellowish white light region. Thus, these results showed that the present YCaSBDy glasses could be aptly suitable for cool white light emitting diodes as well as glass scintillation applications.