New double perovskite Cd2MgTeO6:Sm3+, Na+ tellurate phosphors with abnormal thermal quenching for applications in white and plant growth lighting

New Sm 3+ doped Cd 2 MgTeO 6 tellurate red-emitting phosphors with Na + ions as charge compensation were obtained using a high-temperature solid-state approach at 1000 °C. During this study, the prepared phosphors were subjected to phase purity, particle morphology , luminescence characteristics, thermal stability, and Commission Internationale de L′ Eclairage (CIE) chromaticity. The critical quenching concentration of Sm 3+ doped Cd 2 MgTeO 6 phosphor was 2 mol%. According to Dexter's theory and the calculated R c value (22.21 Å), the dipole-dipole interaction causes the phenomenon of concentration quenching. Particularly, the Cd 2 MgTeO 6 :2 mol%Sm 3+ , 2 mol%Na + phosphor exhibited an evident red-light emission (647 nm) at λ ex  = 407 nm because of the 4 G 5/2 to 6 H 9/2 level transition of Sm 3+ . Its internal quantum efficiency (IQE) was 38.87%. It is worth noting that the Cd 2 MgTeO 6 :Sm 3+ , Na + phosphor exhibited abnormal thermal quenching (ATQ) characteristics, and the luminous intensity of the Cd 2 MgTeO 6 :2 mol%Sm 3+ , 2 mol%Na + increased by 7.20% at 480 K compared with the initial temperature. In addition, white LEDs and red LEDs were successfully manufactured with a 408 nm chip. The prepared red LED showed the emission spectrum similar to the absorption spectrum of Phytochrome P r , which is expected to be applied in plant growth. The w-LED had a CCT (correlated color temperature) of 4790 K, color rendering index of 91, and color coordinates of (0.348, 0.335). Therefore, the Cd 2 MgTeO 6 :Sm 3+ , Na + phosphor has demonstrated potential applications in w-LEDs and plant growth LEDs.