Synthesis and luminescence properties of deep-red-emitting LiAlSi2O6:Mn4+ for plant growth lighting

Light can improve the growth and development of most plants, and the red/deep-red light in the 600–760 nm region is very good for phytochrome red and phytochrome far-red of plants, causing a great interest in the research and development of the deep-red-emitting luminescence materials. In this work, a pure phase LiAlSi 2 O 6 :Mn 4+ with monoclinic crystal structure and only luminous center (Mn 4+ ) is synthesized successfully in air. The excitation spectrum of LiAlSi 2 O 6 :Mn 4+ covers the region from 220 to 550 nm owing to the O 2− - Mn 4+ charge transfer and the 4 A 2g → 4 T 1g and 4 T 2g transitions of Mn 4+ . We observe the deep-red emission of LiAlSi 2 O 6 :Mn 4+ with emission peak at ∼663 nm in the range of 600–850 nm due to the transitions 2 E g → 4 A 2g of Mn 4+ and analyze the luminous mechanism. The optimal doping concentration of Mn 4+ (0.1mol%) is determined by the concentration dependent emission spectra. We analyze the concentration quenching mechanism and investigate the lifetimes of LiAlSi 2 O 6 :Mn 4+ with different Mn 4+ concentration. The good thermal stability of LiAlSi 2 O 6 :Mn 4+ is confirmed via the temperature dependent emission spectra. The potential applications of LiAlSi 2 O 6 :Mn 4+ in plant growth LED lighting are estimated by comparison of spectral properties of LiAlSi 2 O 6 :Mn 4+ and plant.