Synthesis and luminescence properties of a novel deep red phosphor Li2ZnTi3O8:Mn4+ for plant-cultivation

Abstract

In this thesis, a novel ultraviolet-activated Li₂ZnTi₃O₈:Mn⁴⁺ red emitting phosphor is prepared by the traditional high-temperature solid-state reaction method in air. The crystal structure, luminescence properties and decay curves of the phosphor are studied in detail. The sample belongs to spinel cubic crystal structure and there are abundant [TiO₆]^8- octahedron sites can be occupied by Mn⁴⁺. The Li₂ZnTi₃O₈:Mn⁴⁺ phosphor shows the red emission in region of 600-800 nm with a maximum at ~681 nm under 330 nm excitation, which can promote the plant growth. The optimal Mn⁴⁺ doping concentration is ~0.3 mol%, which is higher than that of other hosts. By calculating the crystal field strength (Dq) and Racah parameter B, we can evaluate that there is a strong crystal environment of Mn⁴⁺ in the Li₂ZnTi₃O₈ host lattice, which major comes from the ²E_g → ⁴A_2g transition of Mn⁴⁺ ion. Furthermore, the characteristics of thermal quenching are also studied, poor thermal quenching performance may be due to high doping concentration of Mn⁴⁺. All data suggest that Li₂ZnTi₃O₈:Mn⁴⁺ phosphor can be a potential application in plant-cultivation.

Keywords: Li(2)ZnTi(3)O(8):Mn(4+); Plant-cultivation; Red emitting.