Insight into luminescent properties, energy transfer and thermal stability of NaBa 4 (AlB 4 O 9 ) 2 Cl 3 :Ce 3+ , Tb 3+ phosphors

A series of Ce 3+ and Tb 3+ singly‐ and co‐doped NaBa 4 (AlB 4 O 9 ) 2 Cl 3 (NBAC) phosphors have been synthesized via high‐temperature solid state route. The crystal structure, morphology, photoluminescent properties, thermal properties and energy transfer process between Ce 3+ and Tb 3+ were systematically investigated. The structure refinements indicated that the phosphors based on NBAC crystallized in P 42 nm polar space group in monoclinic phase. The emission color could be tuned from blue (0.1595, 0.0955) to green (0.2689, 0.4334) via changing the ratio of Ce 3+ /Tb 3+ . The energy transfer mechanism of Ce 3+ /Tb 3+ was verified to be dipole–quadrupole interaction via the examination of decay times of Ce 3+ based on Dexter's theory. The good thermal stability showed the intensities of Ce 3+ at 150°C were about 66.9% and 64.88% in NBAC:0.09Ce 3+ and NBAC:0.09Ce 3+ , 0.07Tb 3+ of that at room temperature, and the emission intensities of Tb 3+ remained 102.41% in NBAC:0.11Tb 3+ and 95.22% in NBAC:0.09Ce 3+ , 0.07Tb 3+ due to the nephelauxetic shielding effect and the highly asymmetric rigid framework structure of NBAC. The maximum external quantum efficiency (EQE) of Ce 3+ in NBAC:0.09Ce 3+ , y Tb 3+ phosphors could reach 43.38% at y  = 0.13. Overall, all the results obtained suggested that NBAC:Ce 3+ , Tb 3+ could be a promising option for n‐UV pumped phosphors.