Abnormal thermal quenching and optical performance of new niobate perovskite Sr3LaNb3O12:Sm3+ phosphors for w-LEDs

Abstract

Novel orange-red Sr3LaNb3O12 (SLNO):xSm3+ (0.01 ≤ x ≤ 0.03) phosphors are successfully prepared using the traditional solid-state method. The feasibility that the SLNO compounds can act as an appropriate host has been effectively demonstrated by unit cell structure and bandgap structure. The phase purity, particle size distribution, and elemental composition of SLNO:Sm3+ phosphors are studied. The luminescence properties, concentration-quenching mechanism, color purity, thermostability, CIE chromaticity coordinates, and correlated color temperature (CCT) of the obtained SLNO:Sm3+ products are also discussed. Under 408 nm excitation, SLNO:0.10Sm3+ sample emits a bright orange-red light at 598 nm owing to the 4G5/2 to 6H7/2 transition of Sm3+. The concentration-quenching mechanism is found to be dipole-dipole interaction by the calculated Rc value (17.12 Å) and Dexter's theory. Impressively, the color purity of the phosphors is high and stable (all reach 99.9%), which is rarely affected by the Sm3+ doping concentration. It is worth noting that the obtained phosphors exhibit an abnormal thermal quenching (ATQ) behavior, increasing by 16.12% from 300 to 380 K (SLNO:0.10Sm3+). The CIE x and y chromaticity coordinates vary slightly with the change of temperature, indicating a good thermostability. The mechanism of ATQ has been studied as the lattice defects, and the thermal activation energy is calculated to be 0.51 eV. Ultimately, a white-light-emitting diode (w-LED) with a high color rendering index (Ra) of 88 and a CIE chromaticity coordinate of (0.333, 0.333) has been prepared. The results above reveal the potential of SLNO:Sm3+ to be widely used in w-LEDs.