High-entropy sesquioxide X2O3 upconversion transparent ceramics

In this study, a high-entropy approach was used to design a highly transparent (81.3% in-line transmittance) sesquioxide X 2 O 3 ceramics, in which a single-phase solid solution, with the general formula (Lu 0.2 Y 0.395 Gd 0.2 Yb 0.2 Tm 0.005 ) 2 O 3 , was obtained after sintering under vacuum with La 2 O 3 and ZrO 2 as the sintering additives. Upconversion emission from Tm 3+ ion at 485 nm was demonstrated upon the 980 nm laser emission excitation as a result of cooperative energy transfer from the Yb 3+ ions. High-resolution scanning electron microscope (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) elemental mapping showed that the obtained transparent ceramics were pore-free and without segregation of different elements.