LAUSR

The rich compositional and structural diversity of borophosphates provides a wide variety of host lattices for luminescent materials. Herein, we report a borophosphate, CsNa2REE2(BO3)(PO4)2 (REE = Y, Gd), with a new type of three-dimensional (3D) anionic framework of [REE2(BO3)(PO4)2]∞. In this structure, REE3+ ions are in a linear array and the nearest intraline REE-REE distance is above 6.9 Å. Surprisingly, the Eu3+ activated phosphors CsNa2REE2(1-x)Eu2x(BO3)(PO4)2 show an insignificant concentration quenching effect; the higher the Eu3+ concentration, the larger the absolute luminescent external quantum yield. The 100% Eu3+ phosphor CsNa2Eu2(BO3)(PO4)2 possesses an IQY of 59% under 394 nm excitation. Moreover, CsNa2Eu2(BO3)(PO4)2 phosphor possesses superior thermal stability in the range 30-200 °C, retaining more than 96% of its initial intensity at 200 °C. We believe the prepared phosphor has potential application as a red phosphor for NUV excited LEDs.