Synthesis, structural and luminescence investigations of novel Na3Bi5(PO4)6: Sm3+Eulytite phosphors for photonic applications

For the first time, a new eulytite-type Na3Bi5(PO4)(6): Sm(3+)phosphor was synthesized via high temperature solid-state reaction method and its structure, luminescence and thermal stability were investigated and discussed. XRD pattern revealed Na3Bi5(PO4)(6): Sm3+ was well crystallized into body-centered cubic structure with I43d (220) space group. FT-IR and Raman spectra analysis show that the doping of Sm3+ did not greatly altered the characteristic vibration modes of PO4 and BiO6 groups. A diagram was proposed to illustrate the lattice structure of eulytite crystal. All Na3Bi5(PO4)(6):Sm3+ exhibited electron transition of Sm3+ from 6H(15/2) ground state to various energy level in UV-visible and IR regions. However, as Sm(3+ )amount increasing, energy band gap decreased from 4.05 to 3.70 eV. Under the excitation of 404 nm, all Na3Bi5(PO4)(6): Sm3+ exhibited reddish-orange emission. Concentration quenching was observed for Sm3+ doping amount reached to 1 mol%, and 0.8Sm(3+) doped phosphor showed the biggest quantum efficiency of 89%. Based on emission spectra, Judd-Ofelt parameters were calculated to evaluate the symmetry sites surrounding Sm3+ ions. CIE color chromaticity analysis verified the reasonable color coordinate and color purity of intense reddish-orange emission. The decay and luminescence thermal quenching were studied and possible mechanism were analyzed as well. Good thermal stability was obtained with a high activation energy Delta E of 0.256 eV. The above results demonstrated that Na3Bi5(PO4)(6): Sm3+ phosphors can be used as an appropriate reddish-orange component for developing WLEDs.

Automated summary

In this study, a new red-orange phosphor Na3Bi5(PO4)(6): Sm3+ was successfully synthesized via high temperature solid-state reaction. The structure, luminescence, and thermal stability of the phosphor were investigated. The results showed that Na3Bi5(PO4)(6): Sm3+ exhibited good crystallinity and luminescence properties, making it suitable for developing white LEDs.