Luminescence and energy transfer of co-doped Sr5MgLa2(BO3)6:Ce3+,Mn2+

Abstract

In this work the photoluminescence (PL) of co-doped Sr₅MgLa₂(BO₃)₆:Ce³⁺,Mn²⁺ as well as the energy transfer (ET) from Ce³⁺ to Mn²⁺ was examined. To this end, powder samples with different Mn²⁺ concentrations were synthesised via high temperature solid state reaction. Phase purity of prepared samples was investigated by X-ray powder diffraction. To elucidate the PL properties of Sr₅MgLa₂(BO₃)₆:Ce³⁺,Mn²⁺, emission and excitation spectra along with diffuse reflectance spectra were recorded. Additionally, fluorescence lifetime measurements were performed. To study the temperature behaviour of the emission of Sr₅MgLa₂(BO₃)₆:Ce³⁺,Mn²⁺, PL and lifetime measurements were conducted from 100 to 500 K. Furthermore, external quantum efficiencies were determined and chromaticity coordinates were calculated. It was found that co-doped Sr₅MgLa₂(BO₃)₆:Ce³⁺,Mn²⁺ possesses two emission bands located in the violet/blue and deep red range of the electromagnetic spectrum. Moreover, it turned out that ET from Ce³⁺ to Mn²⁺ in Sr₅MgLa₂(BO₃)₆:Ce³⁺,Mn²⁺ takes place via an exchange interaction mechanism. Temperature dependent PLD measurements reveal that thermal quenching of emission is mainly caused by the Mn²⁺ ions. Finally, quantum efficiency of Ce³⁺ doped Sr₅MgLa₂(BO₃)₆:Ce³⁺ was found to be close to unity.