Luminescence properties and energy transfer behavior of colour-tunable white-emitting Sr4Al14O25 phosphors with co-doping of Eu2+, Eu3+ and Mn4+

Abstract

Eu2+, Eu3+ and Mn4+ co-doped Sr4Al14O25 phosphors were synthesized in air by high temperature solid-state reaction. The coexistence of Eu2+, Eu3+ and Mn4+ in Sr4Al14O25 was detected and verified from X-ray photoelectron spectra (XPS), photoluminescence (PL)/photoluminescence excitation (PLE) spectra and diffuse reflection spectra. The crystal structure, luminescence properties and energy transfer between Eu2+ and Mn4+ were investigated scientifically. Under ultraviolet excitation, a broad emission band with peak at 496 nm was ascribed to a 4f65d-4f7 transition of Eu2+, and another five narrow emission bands were attributed to 4f-4f transitions of Eu3+. The sharp emission band with peak at 659 nm was generated from the spin-forbidden electronic transition 2Eg-4T2 of Mn4+. The energy transfer between Eu2+ and Mn4+ was demonstrated following the nonradiative electric dipole-dipole interaction, and the energy transfer efficiency reached 58.16%. The emission colour of Sr4Al14O25:Eu,Mn4+ can be tuned from blue-green (0.2396, 0.3332) to white (0.3465, 0.2906) with increasing concentrations of Mn4+.