Optical Properties and Energy Transfer of NaCaPO₄:Ce³⁺,Tb³⁺ Phosphors for Potential Application in Light‐Emitting Diodes

Abstract

Abstract NaCaPO 4 :Ce 3+ ,Tb 3+ phosphors were prepared by a solid‐state reaction. Their luminescence properties reveal that an efficient energy transfer from the Ce 3+ to Tb 3+ ions occurs, and its mechanism is a resonant type by means of a dipole–quadrupole reaction. The critical distance of the energy transfer has been calculated by concentration‐quenching and spectral‐overlap methods. The varied emitted color of the phosphors from blue to yellow‐greenish can be achieved by properly tuning the relative ratio of Ce 3+ and Tb 3+ through the energy transfer from the Ce 3+ to Tb 3+ ions. These results indicate that NaCaPO 4 :Ce 3+ ,Tb 3+ is potentially useful as a highly efficient, green‐emitting, UV‐convertible phosphor for white‐light‐emitting diodes. Moreover, the accurate oscillator strength ratio of the electric quadrupole‐to‐dipole transitions for the Tb 3+ ion was obtained to be about 10 –3 , which may be of much significance in the estimate of the critical distance of the dipole–quadrupole interaction between Ce 3+ and Tb 3+ ions through Dexter's energy‐transfer theory.