Synthesis and photoluminescence properties of a new blue-light-excitable red phosphor Ca2LaTaO6:Eu3+ for white LEDs

In this paper, a series of Eu 3+ -activated double-perovskite Ca 2 LaTaO 6 (abbreviated as CLT: x Eu 3+ ; x  = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8) red-emitting phosphors have been successfully synthesized via the conventional high-temperature solid-state reaction method. These samples were characterized by X-ray diffraction, Rietveld refinement , field-emission scanning electron microscope , elemental mapping, energy-dispersive spectrum, room-temperature photoluminescence , decay lifetimes, quantum efficiency, CIE color coordinates, and temperature-dependent emission spectra . Interestingly, under blue excitation into the 7 F 0 → 5 D 2 transition of Eu 3+ at 466 nm, the CLT: x Eu 3+ phosphors could emit bright red light corresponding to the 5 D 0 → 7 F J (J = 1, 2, 3, 4) transitions. Their luminescence properties have been investigated as a function of the Eu 3+ ions concentration . It was found that the CLT:0.4Eu 3+ sample exhibited the strongest emission intensity, and the concentration quenching effect was caused by the dipole-dipole interaction among Eu 3+ activators. Impressively, the emission intensity of the as-prepared CLT:0.4Eu 3+ phosphors was about 4.3 times higher than the commercial Y 2 O 3 :Eu 3+ red phosphors. Moreover, the CLT:0.4Eu 3+ sample had excellent CIE color coordinates of (0.665, 0.334) and supereminent color purity of 95.3%. Notably, the study on temperature-dependent emission spectra of the CLT:0.4Eu 3+ sample revealed its good thermal stability and color stability at high temperatures. These excellent photoluminescence properties of CLT:0.4Eu 3+ phosphors indicated their promising application potential in white light-emitting diodes as blue-light-excitable red phosphors.