Enhanced upconversion and downshifting emissions from Tb³⁺, Yb³⁺ co-doped CaZrO₃ phosphor in presence of Li⁺ ions

Abstract

This paper reports the enhanced green photoluminescence from Tb3+, Yb3+ co-doped CaZrO3 phosphor in the presence of Li+ ion synthesized through solid state reaction technique. The structural studies show an increase in the particle size and a shrink in crystal lattice due to Li+ co-doping in the phosphor. The phosphor sample emits intense green upconversion emission (UC) due to Tb3+ ions on excitation with 980 nm radiation which is further enhanced ∼28 times on Li+ co-doping. The lifetime of 5D4 level of Tb3+ ion decreases in the presence of Li+ ions due to increase in asymmetry in crystal field. The downshifting (DS) emission intensity monitored on 378 and 487 nm excitations is also enhanced in the presence of Li+ ions. Thus, the Tb3+, Yb3+, Li+ co-doped CaZrO3 phosphor can be a suitable candidate for UC solid state lighting.