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 solidphase 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.