Synthesis and luminescence properties of far-red emitting Li1.6Mg1.6Sn2.8O8:Fe3+ phosphor: Plant growth LED applications

Plant greenhouse planting has aroused great attention to the development of plant growth light-emitting diode (LED) light source. Far-red emitting phosphors as the main component of plant growth LED lighting have been studied more and more widely. In this study, Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ with far-red emission for plant LED lighting is synthesized in air. X-ray diffractometer (XRD) with the energy dispersive spectroscopy (EDS) is used to test XRD patterns, EDS, and the element mapping diagrams, confirming that Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ has a hexagonal crystal structure of with pure phase Li 1.6 Mg 1.6 Sn 2.8 O 8 . Photoluminescence excitation (PLE) spectrum, time-resolved PL spectra, decay curves, photoluminescence (PL) spectrum, as well as concentration and temperature dependent PL spectra are investigated in detail. Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ under excitation at 305 nm shows far-red emission peaking at ∼702 nm due to the transition 4 T 1 ( 4 G) → 6 A 1 ( 6 S) of Fe 3+ ion in octahedron [FeO 6 ]. PL spectrum of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ matches with the absorption spectra of plants during the process of photosynthesis, indicating a promising application of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ in plant growth LED lighting. Time-resolved PL spectra prove the only luminescence center (Fe 3+ ). Concentration dependent PL spectra confirm the optimal Fe 3+ concentration (0.8 mol%) and the concentration quenching mechanism is analyzed. The temperature dependent PL spectra show good thermal stability of Li 1.6 Mg 1.6 Sn 2.8 O 8 :Fe 3+ and the heat quenching mechanism is explained.