Design and theoretical study of superlative quantum efficiency and thermal stability phosphor: The system of Sr9Eu(PO4)7

The rare breed of phosphor material that exhibits constantly strong luminescence without undergoing quenching are designed to improve the performance of the phosphor. The Eu3+ ion occupies the sites of a quadrangular bipyramid geometry (connected by O–P–O–Eu–O–P–O bonds) that serve to effectively isolate individual Eu3+ atoms from each other in Sr9La1−xEux(PO4)7 system. Accordingly, the photoluminescence (PL) intensity continued to grow up to 100 mol% concentration of Eu3+, and this gave a rise to the prolonged lifetime to 2.51 ms in parallel with preeminent quantum efficiency up to 90%. Temperature dependent PL measurements of Sr9Eu(PO4)7 phosphor possessed stable emission to 83% of its room temperature value at 423 K. Here, we propose a new configurational coordination diagram on the bases of shape of charge transfer state. Depending on this model, the PLE spectrum can provide approximate information that are important parameters in phosphor such as the quantum efficiency, thermal quenching activation energy and optimal concentration of active ion. By virtue of this model and the rare breed phosphor material that are reported for the first time, we could easily choose a Sr9Eu(PO4)7 crystal as potential red-emitting phosphors of the future replacement decisions for lighting.