Effect of host-structure on the charge of europium ion

This letter describes the nature of rare-earth dopant state in oxides/borates/vanadate hosts. The dopant charge is controlled by host structure, but not by charge-matching. In the preparation of Eu2+ activated blue phosphor Eu(NO3)3 is the starting material. Even in the oxidation environment of combustion process Eu3+ ion gets reduced into Eu2+ in the blue phosphor synthesis. Synthesis of Eu3+ activated red phosphor is a straight-forward reaction