A red-emitting Sm3+-activated BaLaMgNbO6 phosphor for WLED applications obtained by using an isotopic doping strategy (Y → La)

BaLa1-x-yMgNbO6: 1-x-y MgNbO 6 : xSm3+, 3+ , yY3+ 3+ phosphors were successfully synthesized via high-temperature solid-state reaction method. The crystal structure of representative samples was determined using X-ray diffraction and Rietveld refinement, confirming high phase purity of the prepared phosphors. In the singly doped BaLa1-xMgNbO6: 1-x MgNbO 6 : 0.05 S m 3+ sample, red emission was observed under 406 nm excitation with an internal quantum efficiency of 27.8 %. The thermal stability at 599 nm (483 K) retained 72.39 % of the emission intensity. To further enhance the luminescent properties, co-doping strategy was employed by substituting Y 3+ for La3+ 3+ ions. This adjustment significantly improved the brightness of the phosphors. For instance, in BaLa0.93MgNbO6: 0.93 MgNbO 6 : 0.05 S m3+, 3+ , 0.02Y3+, 3+ , the emission intensity at 599 nm was enhanced by 3.27 times compared to BaLa0.95MgNbO6: 0.95 MgNbO 6 : 0.05 S m3+, 3+ , with an internal quantum efficiency increased from 27.8 % to 60.2 %. Moreover, the color purity of BaLa1-x-yMgNbO6: 1-x-y MgNbO 6 : xSm3+, 3+ , yY3+ 3+ phosphors reached 99 %. Warm white LED devices fabricated using BaLa0.93MgNbO6: 0.93 MgNbO 6 : 0.05 S m3+, 3+ , 0.02Y3+ 3+ exhibited a color rendering index (Ra) of 95.7 and a color temperature of 4938K, indicating broad application potential. Experimental results demonstrate that BaLa0.93MgNbO6: 0.93 MgNbO 6 : 0.05 S m3+, 3+ , 0.02Y3+ 3+ phosphors with double perovskite structure are a novel and high-performance material for warm white LED phosphors.