Energy transfer and unusual decay behaviour of BaCa2Si3O9:Eu2+,Mn2+ phosphor

Abstract

In this work the photoluminescence (PL) of BaCa₂Si₃O₉:Eu²⁺,Mn²⁺ and the energy transfer (ET) between Eu²⁺ and Mn²⁺ were examined. A series of powder samples with various Mn²⁺ concentrations were prepared by high temperature solid state route. Phase purity was investigated using X-ray powder diffractometry. Emission and excitation spectra as well as diffuse reflectance spectra were recorded to elucidate the PL properties of co-doped BaCa₂Si₃O₉:Eu²⁺,Mn²⁺. Furthermore, fluorescence lifetime measurements were performed. PL and lifetime measurements were carried out from 100 to 800 K and 100 to 500 K, respectively. Moreover, external quantum efficiencies were determined and colour points were calculated. It turned out that ET from Eu²⁺ to Mn²⁺ is of a resonant type and occurs via dipole–quadrupole interactions. Temperature dependent PL measurements indicate high temperature stability of emission intensity in BaCa₂Si₃O₉:Eu²⁺,Mn²⁺. Finally, it was found that fluorescence lifetimes of Eu²⁺ BaCa₂Si₃O₉ show an unusual increase with increasing temperature.