Upconversion Emission Properties of Erbium- and Ytterbium-Doped Potassium Lithium Tantalate Niobate Ceramics

We investigate the luminescence properties of erbium-doped and erbium-ytterbium-codoped potassium lithium tantalate niobate ceramics prepared by the solid phasesyntheses method. The crystalline structure and surface morphology of these ceramics are tested by x-ray diffraction and scanning electron microscopy. The green, red, and near-infrared upconversion photoluminescence properties are analyzed by the steady-state spectra under 975 nm and 800 nm excitations. These ceramics arewell sintered and tetragonal tungsten type crystalline structure with the 4 mm point group and the P4bm space group. The Er³⁺ upconversion emission integrated intensities increase with theincrease in Er³⁺ ion concentration, while the green emissiondecreases with the increase in Yb³⁺ ion concentration under the 800 nm excitation. An effective energy back transfer process from the Er^{3+ 4}S_3/2 state to Yb³⁺ ground state plays an important role in enhancing the red emission and weakening the green emission.