Novel double perovskite reddish-orange emitting Ca2InNbO6: Sm3+ phosphors with abnormal thermal quenching for white LEDs

A series of reddish-orange emitting Ca2InNbO6:Sm3+ (CINO:Sm3+) phosphors for white light-emitting diodes (w-LEDs) were synthesized using a high-temperature solid-state technique. The synthesized CINO:Sm3+ phosphors are pure phases with monoclinic structures. The optimal Sm3+ doping concentration is 0.02 mol, and concentration quenching is due to the dipole-dipole interaction. Upon 407 nm excitation, the as-prepared CINO:Sm3+ phosphors exhibited strong reddish-orange emission around 602 nm, attributed to the 4G5/2→6H7/2 transition of Sm3+. Surprisingly, the CINO:Sm3+ phosphors revealed an abnormal thermal quenching (ATQ) phenomenon, and when the temperature of the phosphors was raised to 380 K, their emission intensity increased by more than 15%. The CINO:0.02Sm3+ phosphor had a high color purity (98.9%) and reddish-orange chromaticity coordinates (0.608, 0.388). Meanwhile, the manufactured w-LED demonstrated a good color rendering index (Ra = 93), decent CCT (5752 K), and Commission International de l′Eclairage (CIE) chromaticity coordinates (0.327, 0.335). The experimental results demonstrated the superiority of the CINO:Sm3+ phosphors in w-LEDs.