Enhanced visible and mid-IR emissions in Er/Yb-codoped K0.5Na0.5NbO3 ferroelectric ceramics

Er3+/Yb3+-codoped K0.5Na0.5NbO3 (KNN) ceramics have been fabricated by the solid state reaction method. Under the excitation of 980 nm, Er3+ ions exhibit visible up-conversion emissions as well as the near-infrared (NIR) and middle-infrared (MIR) emissions. Yb3+ ions are used as the sensitizer to codope with Er3+ in the KNN host in the purpose of improving the emission efficiency and PL intensities, i.e. significantly enhancing the blue, green, red and MIR emissions of Er3+. The concentration quenching effect has been discussed together with the up-conversion emissions and corresponding luminescent lifetimes. The energy transfer processes between Er3+ and Yb3+ have been investigated with the relationship between the Yb3+ concentration and PL intensities. Due to the moderate ferroelectric and piezoelectric properties of the host, the ceramics show multifunctional performance and potential in the application of optoelectronic areas.