Highly transparent Er3+/Yb3+ co-doped yttria ceramics were fabricated by a solid-state reaction method using high purity Y2O3, Er2O3 and Yb2O3 powders as starting materials and La2O3 as an additive. The microstructure evolution and optical properties of the ceramics were investigated. Fully dense Y2O3: Er3+,Yb3+ ceramics with mean grain size of about 60 mu m were obtained by vacuum sintering at 1800 degrees C for 10 h. The highest transmittance of the ceramic sample is more than 75% in the range from 500 to 3000 nm. Under the 980 nm laser diode excitation, the ceramic sample exhibits intense up-conversion luminescence, which is centered at 561 and 662 nm respectively. (C) 2012 Elsevier B.V. All rights reserved.