Color-tunable up-conversion luminescence of Er³⁺/Yb³⁺ co-doped (K,Na)NbO₃ ceramics

To investigate the effect of Yb³⁺ doping on the up-conversion emissions, the Yb³⁺/Er³⁺ co-doped (K,Na)NbO₃ smart ferroelectric ceramics have been synthesized by the conventional solid-state reaction. The results here illustrated that the green and red up-conversion emission intensities of these ceramics excited under 980 nm increased with the increasing content of Yb₂O₃ and achieved the maximum value at x=0.5%. The ratio of green and red emission intensity could be adjusted by changing the content of Yb₂O₃, and the mechanism of up-conversion processes involved a two-photon absorption. In addition to the admirable intrinsic piezoelectric properties of KNN, this kind of material may have potential application as a multifunctional device by integrating its up-conversion and piezoelectric property.