Structural and Optical Properties of Dy3+ Doped with an Eulytite Type NaBaBi2(PO4)3 Phosphor for White Light Emitting Diodes

Abstract

A series of NaBaBi(_2-x)(PO₄)₃:xDy³⁺ eulytite type phosphors with varying doping concentrations were synthesized using a conventional solid-state reaction. The crystalline nature and phase formation of the phosphor were confirmed by the PXRD technique. FESEM was used to examine the surface morphology. UV-DRS measurements were used to quantify the band gap of the host and Dy³⁺ ion doped phosphors. The phosphors’ photoluminescence properties were thoroughly investigated. According to the excitation spectra, these phosphors show a strong absorption band in the near-ultraviolet (NUV) region, extending from 250 to 450 nm. Under the excitation of 352 nm, the peaks of the emission spectra of Dy³⁺ ions are located at 485 nm (blue), 575 nm (yellow) and 666 nm (red), corresponding to the magnetic dipole ⁴F_9/2®⁶H_15/2 transition, the electric dipole ⁴F_9/2®⁶H_13/2 transition and the ⁴F_9/2®⁶H_11/2 transition. The optimal concentration of Dy³⁺ doped phosphor is x = 0.075 and the major concentration quenching mechanism is accomplished by energy transfer between the nearest-neighbour ions. The critical transfer distance (R_c) is estimated to be about 19.01. The Commission International deI’Eclairage (CIE) of NaBaBi_1.925(PO₄)₃:0.075Dy³⁺ phosphor was calculated to be (x = 0.341 and y = 0.374), which was very close to the “ideal white” (x = 0.33, y = 0.33). Present findings suggest that the phosphor might be a viable option for producing a white-light-emitting phosphor under NUV activation.