Photoluminescence properties of a novel orange red emitting Sr4Al14O25:Sm3+ phosphor and PL enhancement by Bi3+ co-doping

A novel orange red emitting Sr4Al14O25:Sm3+ and Sr4Al14O25:Sm3+, M3+ (M = Bi, Dy, Nd) phosphors were synthesized by high temperature solid state reaction method. The phosphor samples were characterized by X-ray diffraction and Scanning Electron Microscopy. UV–visible absorption, photoluminescence emission and excitation spectra were investigated for the phosphor with various doped concentrations of Sm3+ and Bi3+ ions and different amount of H3BO3 as a flux. The emission intensity of Sm3+ ions in the Sr4Al14O25 host largely enhanced with the amount of flux, concentration of activator (Sm3+) ion and co-activator (Bi3+) ion. The maximum intensity was observed in the phosphor prepared using 40 mol% H3BO3 as a flux and 2 at.% Sm3+ ions as an activator sintered at 1350 °C. Addition of 2 at.% Bi3+ ion drastically enhanced the emission intensity; the increase by Dy3+ ion was not so pronounced but Nd3+ ion largely suppressed the emission intensity. The increase of emission intensity by Bi3+ ion addition was explained on the basis of higher absorption of excitation energy by Bi3+ ions and efficient energy transfer from Bi3+ to Sm3+ emission center.

Photoluminescence excitation spectrum (λemi = 595nm) (dotted lines), and emission spectrum (λexc = 310nm) (solid line) of Sr4Al14O25:2 at.% Sm3+, x at.% Bi3+ phosphor at room temperature. The inset shows the digital micrograph of the phosphor in black light.Figure optionsDownload high-quality image (164 K)Download as PowerPoint slideHighlights
► A novel orange red light emitting Sr4Al14O25:Sm3+, M3+ (M = Bi, Dy, Nd) phosphor was synthesized by solid state method.
► PL spectra were measured under various concentrations of flux, activator and co-activators.
► Bi3+ addition enhanced the emission intensity by more than 2 fold.
► Enhanced PL by Bi3+ is due to higher energy absorption by Bi3+ and efficiently transferred it to Sm3+.