The local symmetry of trivalent europium ion activated Li4Ca2B8O16 red-emitting phosphors with high color purity and excellent thermal stability.

Exploring for red-emitting phosphor materials with supper property plays a key role in the development of white light-emitting diodes (WLEDs). Simultaneously, the crystal structure has a crucial effect on its luminescence properties. In this work, we synthesized a type of new red-emitting Li 4 Ca 2 B 8 O 16 : Eu3+ phosphor via the solid-state reaction. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the correspondence between local symmetry and luminescence properties were investigated in detail. Under the optimal 393 nm excitation, Li 4 Ca 2 B 8 O 16 : 0.33Eu3+ shows a strong red emission located at 612 nm ascribed to the 5D 0 →7F 2 transition of Eu3+. The calculated Judd-Ofelt parameters (Ω 2 and Ω 4) have clarified that Eu3+ has lower symmetry without an inversion center, resulting in the high value of R/O (the emission intensity ratio of 5D 0 →7F 2 to 5D 0 →7F 1) of 7.95 at x = 0.33 mol. The Li 4 Ca 2 B 8 O 16 : 0.33Eu3+ phosphor exhibits a high color purity of 94.99% with the chromaticity coordinates of (0.6547, 0.3449), perfect internal quantum efficiency (99.75%) and excellent thermal stability at high temperature (90.91% at 150 °C). The results indicate that this new Li 4 Ca 2 B 8 O 16 : Eu3+ phosphor can be used as the potential red component for pc-WLEDs. [Display omitted] • A series of new red-emitting Eu3+ doped Li 4 Ca 2 B 8 O 16 phosphors have been synthesized. • The incorporation of more Eu3+ ions leads to lower structural coordinated symmetry and higher color purity. • The Li 4 Ca 2 B 8 O 16 :0.33Eu3+ owns a high color purity of 94.99% and CIE of (0.6547, 0.3449). • Compared with the emission intensity at 25 °C, the overall emission intensity still remains 90.91% at 150 °C. [ABSTRACT FROM AUTHOR]