Energy transfer, superior thermal stability and multi-color emitting properties of langbeinite-type solid-solution phosphor K2Dy1.5–Eu Ta0.5(PO4)3

Langbeinite type compounds are a large kind of oxometallate with good flexibility structure. Herein, we synthesized a new langbeinite type compound K2Dy1.5Ta0.5(PO4)3, in which the Dy3+ and Ta5+ were blended to occupy the same crystallographic sites. Simultaneously, solid solutions of K2Dy1.5–xEuxTa0.5(PO4)3 (x = 0–1.5) were prepared and their photoluminescence properties were investigated. Due to energy transfer from Dy3+ to Eu3+, both Dy3+ and Eu3+ characteristic emissions are observed under 393 nm light excitation. The emitting color of K2Dy1.5–xEuxTa0.5(PO4)3 turns from green through yellow to red by simply adjusting the Eu3+ concentration from 0 to 0.4. Moreover, K2Dy1.48Eu0.02Ta0.5 (PO4)3 phosphor possesses excellent fluorescence thermal stability and exhibits zero thermal quenching at 150 °C. These results manifest that K2Dy1.5–xEuxTa0.5(PO4)3 solutions are promising multi-color emitting phosphors candidate for near-UV LED.