Color tunable phosphor CaMoO4:Eu3+,Li+ via energy transfer of MoO42−–Eu3+ dependent on morphology and doping concentration

Abstract The cooling rate and the solubility of molybdate in molten salt play crucial roles on the microscopic morphologies and photoluminescence (PL) properties of the phosphor CaMoO 4 :Eu 3+ ,Li + . Undoped CaMoO 4 exhibits self-activated green PL with a broad emission band which is assigned to the spin forbidden 3 T 1,2 – 1 A 1 transition of the MoO 4 2− complex. The strong UV absorption of undoped CaMoO 4 is originated from the charge transfer from O 2− ligands to the central Mo 6+ ions inside MoO 4 2− group. The emission of the phosphor CaMoO 4 :Eu 3+ ,Li + obtained by molten salt synthesis (MSS) at 900 °C is composed of a broad green emission from MoO 4 2− and a group of sharp red emission peaks from f–f transitions of Eu 3+ . Efficient energy transfer from MoO 4 2− to Eu 3+ is responsible for the increased red PL of the phosphor. The dependence of energy transfer efficiency on the processing conditions and doping concentration has been investigated.