The effects of preparation conditions on the structural and up-conversion properties of NaYF4:Yb3+, Er3+ nano powders

The NaYF4:Yb3+, Er3+ powders were prepared by a co-precipitation method. The relationship between the phase ratio of cubic to hexagonal phase and the emission intensity ratio of red to green was investigated. This concluded that the cubic phase dominantly contributed to the red emission, while the green emission was mainly ascribed to the hexagonal phase. The effects of Al3+ doping on UC emission were investigated first. The red emission intensity of the cubic phase was drastically enhanced when 10 mol% Al was added.