Influence of Al3+ on the cross relaxation process and electrical properties of Dy3+ activated Gd2O3 phosphor for white LED application

Gd2O3:Dy3+ Al3+ phosphors is synthesised by a wet-chemical method for various concentrations of Al3+ ion. X-ray diffraction, photoluminescence and impedance spectroscopy are used to understand the physio-chemical properties of the phosphors. The emission spectra of Dy3+ ion exhibit transition peaks centred at 572 nm (yellow), 486 nm (blue) and 669 nm (red). Energy transfer from Gd3+ to Dy3+ is also verified by exciting the phosphors at 274 nm. Some of the Dy3+ ions occupy both C2 and S6 site of Gd3+ ion in Gd2O3 matrix. It is also revealed that the enhancement of Dy3+ emission is strongly correlated to the surface morphology of the phosphors. Introducing Al3+ ions in Gd2O3:Dy3+ phosphor affect the emission properties of Dy3+ ions and its influence is explored at various concentration of Al3+ ions. The energy level diagram is presented to explain the cross-relaxation process among Dy3+ ions and the energy transfer from Gd3+ to Dy3+ ion.