Microstructure and NIR to VIS upconversion luminescence of Y2O3:Er translucent ceramics

Y2O3:5%Er nanocrystalline powder was prepared by low temperature combustion method. The crystal structure and morphology were analyzed by means of XRD and HRTEM. The resultant powders were sintered into translucent ceramics at 1570°C in vacuum for 6 hours. The micrograph of unpolished surface and fracture surfaces showed that the sintered Y2O3:Er ceramics with average grain size at about 10μm had homogeneous micro-structure and low pore volume. Under the excitation of 980 nm, 808 nm and 785 nm diode lasers, respectively, very strong green and red upconversion emissions from Er3+ ions were observed, the power dependence of upconversion emission intensity was measured to deduce the upconversion mechanism. A trend of upconversion intensity increase first and then decrease with the excitation time was also found for the first time.