Luminescence properties and energy transfer study of color temperature tunable CaSrSiO4:Dy3+,Eu3+ white phosphors

A series of CaSrSiO4:xDy3+,yEu3+ white phosphors were successfully synthesized by high-temperature solid-phase reaction technique. The physical phase, optical performance, energy transfer mechanism and thermal stability of the samples were studied. It has been shown that the concentration quenching point of CaSrSiO4:xDy3+ phosphors is x = 0.05 at the excitation of 365 nm. In CaSrSiO4:0.05Dy3+,yEu3+ phosphors, the emission intensity of Dy3+ gradually decreases with the increase of Eu3+ doping concentration. While the emission intensity of Eu3+ first increases and then decreases, the concentration quenching point of Eu3+ is y = 0.08. The analysis of the lifetime decay curves demonstrates the existence of an energy transfer process from Dy3+ to Eu3+ in CaSrSiO4:Dy3+,Eu3+ phosphors. The energy transfer from Dy3+ to Eu3+ is dominated by dipole-dipole interactions, with the highest energy transfer efficiency of 63.1 %. By adjusting the doping concentration of Eu3+, the doping of Eu3+ not only effectively improves the stability of phosphor, but also enables tunable color temperature from cold white light to neutral white light, which is a potentially promising white light emitting material.