Investigating luminescence properties and energy transfer of Ca3(PO4)2: Dy3+/Eu3+ phosphor via hydrothermal synthesis

Abstract

In this paper, Dy3+ doped and Dy3+/Eu3+ co-doped Ca3(PO4)2 phosphors were prepared through hydrothermal synthesis method. pH value in the initial reaction solution had an important effect on the determination of phosphate morphology. With the increase of pH value, the morphology of samples changed from nanorods to nano-spherical grains. The Ca3(PO4)2: Dy3+ phosphors could be efficiently excited by 350 nm and its concentration quenching occurred when the concentration of Dy3+ was beyond 0.03 due to dipole-dipole interaction. With increasing content of Eu3+ in Ca3(PO4)2: Dy3+, Eu3+ phosphors, the emission intensity of Dy3+ decreased, and that of Eu3+ increased to maximum when Eu3+ concentration was 0.08, and then decreased. The energy transfer (ET) from Dy3+ to Eu3+ in Ca3(PO4)2 host was expressed through the quadrupole-quadrupole mechanism, and the maximum of ET efficiency was 82.40%. When Ca3(PO4)2: Dy3+, Eu3+ phosphors excited by 362 nm, the CIE coordinates ranged from (0.295, 0.330) to (0.367, 0.326). Moreover, the samples had good thermal stability. The emission intensity of the sample at 460 K decreased to 85.67% of that at 300 K. Our results display that Ca3(PO4)2: Dy3+/Eu3+ phosphors are potential candidate for applications in the near-UV pumped warm white LEDs.