Synthesis and luminescence properties of Mn4+-activated Ba2LaSbO6 deep-red phosphor

Abstract A series of novel Ba2LaSbO6 (BLS):xMn4+ red-emitting phosphors is synthesized by high-temperature solid-state method. The samples are efficiently excited from 250 nm to 500 nm, which matches well with the wavelengths of UV chips for light-emitting diodes (LEDs). The photoluminescence spectra present a strong emission peak at 678 nm due to 2Eg → 4A2 spin forbidden transition in Mn4+ ions. The decay times decrease from 0.141 ms to 0.071 ms with increasing Mn4+ concentration from x = 0.03–0.2% because of concentration quenching. The values of decay times are within microsecond range, indicating the luminescence to be due to the forbidden transition in the intra-d-shell Mn4+ ions. A nonradiative process in the 3d orbit of Mn4+ ions leads to thermal quenching; the activation energy (Ea) is calculated to be ~0.36 eV, confirming a good thermal stability. Quantum efficiencies of the sample are determined to be 20.2%.