Single- and dual-band emission CaNb2O6:Mn2+: Synthesis and luminescence properties

Abstract

Now free rare earth ions doped materials have attracted a lot of attention. In this work, CaNb2O6:Mn2+ with a pure phase is synthesized by solid-state method in the reducing atmosphere. The crystal structure and luminescence properties of host (CaNb2O6) and CaNb2O6:Mn2+ are investigated. Host (CaNb2O6) under excitation ultraviolet (UV) light emits blue light. CaNb2O6:Mn2+ can show tunable emission from blue to white. Under excitation 260 nm, blue emission of CaNb2O6:Mn2+ is observed owing to the 4T1(4G) → 6A1(6S) transition of Mn2+. When the excitation wavelength is 314 nm, CaNb2O6:Mn2+ emits white light due to the 4T1(4G) → 6A1(6S) transition of Mn2+ and the 6A1(6S)4T1(4G) → 6A1(6S)6A1(6S) transition in Mn2+ - Mn2+ dimers. We measure the concentration dependent spectra of CaNb2O6:Mn2+ and make sure the optimal Mn2+ doping concentration (∼0.8 mol%). We infer that the concentration quenching mechanism is the electric multipolar interaction between nearest-neighbor ions. Based on the temperature dependent spectra of CaNb2O6:Mn2+, we came to the conclusion that CaNb2O6:Mn2+ has a good thermal stability. We analyze the concentration and thermal quenching mechanisms and explain the luminous mechanism by the Tanabe-Sugano energy level diagram of Mn2+ ion. This research results provide a framework for creating Mn2+-doped luminescent materials.