Warm white light generation in γ-irradiated Dy3+, Eu3+ codoped sodium aluminoborate glasses

This paper mainly emphasizes on the warm white light generation through an energy transfer from Dy3+ to Eu3+; Eu2+ to Dy3+, Eu3+ ions doped in sodium aluminoborate glasses. Absorption and FTIR studies confer that γ-irradiation causes the compaction of the borate network by breaking the bonds between trigonal elements leading to a decrease in the optical band gap. Electron paramagnetic resonance (EPR) confirms the defects induced in glasses by γ-irradiation. The presence of radiation induced defects and the effective energy transfer between the ions make the decay curves change from single exponential (before irradiation) into non-exponential nature (after irradiation). The non-exponential curves are good-fitted to modified Yokota-Tanimoto model for S= 8 indicating that the nature of energy transfer process is of dipole-quadrupole type. The color coordinates are found to fall in the white light zone of the CIE diagram.