Abstract:The Er³⁺/Yb³⁺ co-doped YPO₄ up-conversion luminescence materials were synthesized by co-precipitation method. The phase structures, morphologies, element components, and optical properties of the as-synthesized samples were characterized by X-ray diffractometry(XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV-visible diffuse reflectance spectroscopy (UV-vis) and up-conversion emission spectroscopy (UPL). The effects of Er³⁺ and Yb³⁺ doping amounts on the up-conversion luminescence properties and phase structures of the as-prepared samples were analyzed. The results show that the samples are pure phase Er³⁺/Yb³⁺ co-doped YPO₄ sub-micron crystals with tetragonal structure, and the Yb³⁺ doping contents have less influence on the phase structure of the samples. The obtained Er³⁺/Yb³⁺ co-doped YPO₄ samples emit the characteristic up-conversion green emissions of Er³⁺. The color purity of the green up-conversion emission from Er³⁺/Yb³⁺ co-doped YPO₄ samples is above 96%. The color temperature of the Er³⁺/Yb³⁺ co-doped YPO₄ samples is similar to daylight. The doping contents (mole fraction) of the Er³⁺ and Yb³⁺ exhibit great influence on the up-conversion luminescence performance of the as-prepared samples. The YPO₄:1%Er³⁺/20%Yb³⁺ sample displays excellent up-conversion luminescence property. The concentration quenching phenomena will occur for Er³⁺/Yb³⁺ co-doped YPO₄ samples when the doping content of Yb³⁺ is above 20% or the doping content of Er³⁺ is above 1%. In addition, the up-conversion luminescence mechanism and energy transition mechanism of Er³⁺/Yb³⁺ co-doped YPO₄ samples were discussed.

Key words: YPO₄; Er³⁺/Yb³⁺ co-doped; up-conversion luminescence properties; co-precipitation method; color purity; luminescence mechanism