Photoluminescence properties of layered perovskite-type strontium scandium oxyfluoride activated with Mn⁴⁺

In this research, we have found that layered perovskite titanate Sr₂TiO₄ doped with Mn⁴⁺ exhibits photoluminescence even at room temperature despite no luminescence from Mn⁴⁺-doped SrTiO₃ with a three-dimensional bulky perovskite structure. The relative position of t_2g orbital of Mn to the valence band is a key factor for appearance of Mn⁴⁺-emission in Sr₂TiO₄:Mn. This result suggested usefulness of layered perovskite-type materials as hosts for Mn⁴⁺-activated phosphors than the bulky perovskite-type materials. Our investigation into photoluminescence of Mn⁴⁺-doped layered perovskite compounds has revealed that strontium scandium oxyfluoride Sr₂ScO₃F activated with Mn⁴⁺ exhibits Mn⁴⁺-emission with a peak at 697 nm under excitation at 300-600 nm and its emission intensity is much stronger than that of Sr₂TiO₄:Mn. The internal and external quantum yields of Sr₂ScO₃F:Mn were determined to be 50.5 and 43.5% under excitation at 345 nm, respectively.