Red-luminescence enhancement of ZrO2-based phosphor by codoping Eu3+ and M5+ (M = Nb, Ta)

Red emission of monoclinic Zr(1−2x)EuxMxO2 (M = Nb, Ta; x = 0.05) was enhanced by the M addition, about five times higher than Zr0.95Eu0.05O2 excited by 395 nm or 469 nm at room temperature. The corresponding quantum yield improves 2–4 times, achieving ∼13%. The luminescence enhancement is attributed to that the codoped Eu3+ and M5+ ions result in the seven-coordinated Eu3+ activators with the low symmetry C1, compared with the eight-coordinated high symmetric (D2d) Eu3+ ions coexisted with oxygen vacancies in Zr(1−x)EuxO2. The thin film of Zr0.90Eu0.05Nb0.05O2, deposited by radio frequency magnetron sputtering method, also shows intensely red emission.

► Red emission of ZrO2:Eu3+ is enhanced by five times through Nb5+ or Ta5+ addition.
► Quantum efficiency is improved by about three times.
► Emission enhancement is ascribed to monoclinic phase and defect elimination.
► Luminescence film shows high transmittance and intense red emission.