Luminescence and energy transfer of Ce³⁺-Eu²⁺ in Ca₉Al(PO₄)₇

Abstract

A series of Ce³⁺, Eu²⁺ and Ce³⁺-Eu²⁺ doped Ca₉Al(PO₄)₇ phosphors are synthesized by a high temperature solid-state method. Under 291 nm excitation, Ca₉Al(PO₄)₇:Ce³⁺ has one emission band at 356 nm, which is attributed to 4f⁰5d¹→4f¹ transition of Ce³⁺. Under 305 nm excitation, Ca₉Al(PO₄)₇:Eu²⁺ presents one emission band at 445 nm, which is assigned to 4f⁶5d¹→4f⁷ transition of Eu²⁺. Energy transfer from Ce³⁺ to Eu²⁺ in Ca₉Al(PO₄)₇ is validated and proved to be a resonant type via a quadrupole-quadrupole interaction. Critical distance (R_c) of Ce³⁺ to Eu²⁺ in Ca₉Al(PO₄)₇ is calculated to be 1.264 nm. Moreover, the emission intensity of Ca₉Al(PO₄)₇:Ce³⁺, Eu²⁺ can be tuned by properly adjusting the relative doping composition of Ce³⁺/Eu²⁺.

Keywords

Energy Transfer / Emission Intensity / Critical Distance / Energy Transfer Efficiency / Optoelectronic Letter