Reddish-orange-emitting CaLa4Ti4O15:Sm3+ phosphors with good thermal stability for WLED applications

Abstract

Reddish-orange emitting CaLa4Ti4O15:Sm3+ phosphors were synthesized via a simple solid-state reaction. The synthesized CaLa4Ti4O15:Sm3+ phosphors revealed dominant excitation at 408 nm and emission at 601 nm with the 6H5/2 → 4F7/2 and 4G5/2 → 6H7/2 transitions, respectively. The transitions are governed by dipole-dipole interaction in the CaLa4Ti4O15:Sm3+ luminescent material. The morphology and crystal structure were investigated, and the material synthesis and chemical compositions were also confirmed. In a study of the effect of Sm3+ ion concentration on the luminescent properties of CaLa4Ti4O15:Sm3+ phosphors, the optimized concentration was found to be 5 mol%. The optimized phosphor powder exhibited Commission Internationale de l′Eclairage (CIE) chromaticity coordinate of (0.610, 0.390) under 408 nm illumination, and the thermal stability was also measured, exhibiting good thermal stability of about 81.7% at 423 K and 67.95% at 483 K. The white light-emitting diode (WLED) device was packaged using CaLa4Ti4O15:Sm3+ phosphors, together with commercial phosphors. The fabricated WLED device exhibited good correlated color temperature and color rendering index values of 5461 K and 83.97, respectively with (0.3341, 0.3997) CIE chromaticity coordinate. The CaLa4Ti4O15:Sm3+ materials as a reddish-orange emitting phosphor are expected to be a highly promising candidate for WLED applications.