Synthesis and photoluminescence properties of novel far-red-emitting BaLaMgNbO 6 :Mn 4+ phosphors for plant growth LEDs.

A series of far-red-emitting BaLaMgNbO 6 :Mn 4+ (BLMN:Mn 4+ ) phosphors were successfully synthesized by a high-temperature solid-state reaction method. Crystal structure and luminescence properties of the obtained samples were systematically investigated. The emission spectra exhibited a strong narrow far-red emission band peaking at 700 nm with a full width at half-maximum (FWHM) of ∼36 nm under 360 nm excitation. The optimal Mn 4+ concentration was about 0.4 mol%. The internal quantum efficiency and CIE chromaticity coordinates of the BLMN:0.4% Mn 4+ phosphor were 52% and (0.7222, 0.2777), respectively. In addition, the luminescence mechanism has been analyzed using a Tanabe-Sugano energy level diagram. Finally, by using a 365 nm near-ultraviolet InGaN chip combined with BLMN:0.4% Mn 4+ phosphors, a far-red LED device was fabricated.