Efficient photoluminescence of Dy3+ at low concentrations in nanocrystalline ZrO2

Nanocrystalline ZrO2:Dy3+ were prepared by sol–gel and the structural and photoluminescence properties characterized. The crystallite size ranges from 20 to 50 nm and the crystalline phase is a mixture of tetragonal and monoclinic structure controlled by dopant concentration. Strong white light produced by the host emission band centered at ∼460 nm and two strong Dy3+ emission bands, blue (488 nm) and yellow (580 nm), under direct excitation at 350 nm were observed. The highest efficiency was obtained for 0.5 mol% of Dy3+. Emission is explained in terms of high asymmetry of the host suggesting that Dy3+ are substituted mainly into Zr4+ lattice sites at the crystallite surface. Luminescence quenching is explained in terms of cross-relaxation of intermediate Dy3+ levels.