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

Abstract

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 40mol% H3BO3 as a flux and 2at.% Sm3+ ions as an activator sintered at 1350°C. Addition of 2at.% 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.