Preparation and Performance of KNN-based Upconversion Transparent Ceramics

Upconversion transparent ceramics K0.5(1-y)Na0.5(1-y)LiyNb1-yBiyO3-Er0.005Yb0.005x(Er3+/Yb3+:KNNLB, x=0-3, y=0-0.09) were fabricated by hot-press sintering process using LiBiO3 as additives. The microstructure, optical transparency and upconversion fluorescence were investigated.The results show that the crystalline phase of the ceramics is orthorhombic-perovskite structure.The ceramics are well densified, and the grain size of the ceramics is about 0.5 £gm.These ceramics present good transparency in the infrared and the long-wavelength visible regions, but the optical transparency declines rapidly in the visible region as the amount of Yb3+ and Er3+ ions increases.The transparency of the ceramics with y = 0.06 and x = 0 reaches 45% in the visible region and over 95% in the infrared region(the thickness of the sample is 0.5 mm).The strong upconversion fluorescence is observed when the ceramics are excited by the 900 nm-wavelength light of an xenon lamp.