Spectroscopy of Mn 4+ in Double Perovskites, La 2 LiSbO 6 and La 2 MgTiO 6 : Deep Red Photon Generators for Agriculture LEDs

Abstract

The optical properties of Mn4+ (3d3) in the double perovskites, La2LiSbO6 and La2MgTiO6, are investigated. The Mn4+ energy levels are calculated using the exchange charge model of crystal-field theory and compared with the experimental spectroscopic data. A comparative study of the optical properties of Mn4+ in the perovskite structure shows that energy of the 2Eg→4A2g emission transition is determined by octahedral site distortion. The greater is the site distortion, the lower is the Mn-O covalent interaction and the higher is the energy of the 2Eg→4A2g emission transition. The work provides guidelines for the development of deep red emitting phosphors for agricultural (horticultural) applications.