Synthesis and luminescence properties of reddish orthosilicate oxyapatite phosphor LiGd9(SiO4)6O2:Sm3+

A series of reddish-emitting apatite-type phosphor LiGd₉(SiO₄)₆O₂:Sm³⁺ was prepared by using an appropriate solid-state method. The photoluminescence (PL), photoluminescence excitation (PLE) spectra, and decay times of the samples were characterized to investigate the photoluminescence properties for application in white light-emitting diodes (w-LEDs). The photoluminescence investigations showed that LiGd₉(SiO₄)₆O₂:Sm³⁺ phosphor emitted reddish emission, which ascribed to the transitions of the Sm³⁺ from the ⁴G_5/2 excited state to the ⁶H_5/2, ⁶H_7/2, and ⁶H_9/2 states, respectively. The critical quenching concentration of Sm³⁺ in LiGd₉(SiO₄)₆O₂ phosphors were determined to be about 3 mol%. Moreover, the spectroscopic data and fluorescence decay dynamics indicate that the energy transfer from Gd³⁺ to Sm³⁺ ions takes place in LiGd₉(SiO₄)₆O₂: Sm³⁺ phosphor. All the results indicated that the LiGd₉(SiO₄)₆O₂: Sm³⁺ phosphor could efficiently assimilate the near ultraviolet (n-UV) light and act as a suitable warm light candidate for n-UV w-LEDs.