Luminescence Properties of CaCe(PO):A (A = Eu/Tb/Mn) Phosphors with Abundant Colors: Abnormal Coexistence of Ce-Eu and Energy Transfer of Ce → Tb/Mn and Tb-Mn.

A series of Eu/Tb/Mn-ion-doped CaCe(PO) (CCPO) phosphors have been prepared via the conventional high-temperature solid-state reaction process. Under UV radiation, the CCPO host presents a broad blue emission band from Ce ions, which are generated during the preparation process because of the formation of deficiency. The Eu-doped CCPO phosphors can exhibit magenta to red-orange emission as a result of the abnormal coexistence of Ce/Ce/Eu and the metal-metal charge-transfer (MMCT) effect between Ce and Eu. When Tb/Mn are doped into the hosts, the samples excited with 300 nm UV light present multicolor emissions due to energy transfer (ET) from the host (Ce) to the activators with increasing activator concentrations. The emitting colors of CCPO:Tb phosphors can be tuned from blue to green, and the CCPO:Mn phosphors can emit red light. The ET mechanism from the host (Ce) to Tb/Mn is demonstrated to be a dipole-quadrapole interaction for Ce → Tb and an exchange interaction for Ce → Mn in CCPO:Tb/Mn. Abundant emission colors containing white emission were obtained in the Tb- and Mn-codoped CCPO phosphors through control of the levels of doped Tb and Mn ions. The white-emitted CCPO:Tb/Mn phosphor exhibited excellent thermal stability. The photoluminescence properties have shown that these materials might have potential for UV-pumped white-light-emitting diodes.